These are articles that WRRC researchers have had published in commercial scientific journals for which WRRC does not hold the copyright. We provide access to the abstract here as an aid to help you identify material that may be of interest.
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Longitudinal dispersion coefficients for numerical modeling of groundwater solute transport in heterogeneous formations
Jonghyun Lee, Massimo Rolle, and Peter K. Kitanidis
Journal of Contaminant Hydrology (2017)
Most recent research on hydrodynamic dispersion in porous media has focused on whole-domain dispersion while other research is largely on laboratory-scale dispersion. This work focuses on the contribution of a single block in a numerical model to dispersion. Variability of fluid velocity and concentration within a block is not resolved and the combined spreading effect is approximated using resolved quantities and macroscopic parameters. This applies whether the formation is modeled as homogeneous or discretized into homogeneous blocks but the emphasis here being on the latter. The process of dispersion is typically described through the Fickian model, i.e., the dispersive flux is proportional to the gradient of the resolved concentration, commonly with the Scheidegger parameterization, which is a particular way to compute the dispersion coefficients utilizing dispersivity coefficients. Although such parameterization is by far the most commonly used in solute transport applications, its validity has been questioned. Here, our goal is to investigate the effects of heterogeneity and mass transfer limitations on block-scale longitudinal dispersion and to evaluate under which conditions the Scheidegger parameterization is valid. We compute the relaxation time or memory of the system; changes in time with periods larger than the relaxation time are gradually leading to a condition of local equilibrium under which dispersion is Fickian. The method we use requires the solution of a steady-state advection-dispersion equation, and thus is computationally efficient, and applicable to any heterogeneous hydraulic conductivity K field without requiring statistical or structural assumptions. The method was validated by comparing with other approaches such as the moment analysis and the first order perturbation method. We investigate the impact of heterogeneity, both in degree and structure, on the longitudinal dispersion coefficient and then discuss the role of local dispersion and mass transfer limitations, i.e., the exchange of mass between the permeable matrix and the low permeability inclusions. We illustrate the physical meaning of the method and we show how the block longitudinal dispersivity approaches, under certain conditions, the Scheidegger limit at large Péclet numbers. Lastly, we discuss the potential and limitations of the method to accurately describe dispersion in solute transport applications in heterogeneous aquifers.
Fast large-scale joint inversion for deep aquifer characterization using pressure and heat tracer measurements
Jonghyun Lee, Amalia Kokkinaki, and Peter K. Kitanidis
Transport Porous Media (2017)
Characterization of geologic heterogeneity is crucial for reliable and cost-effective subsurface management operations, especially in problems that involve complex physics such as deep aquifer storage of carbon dioxide. With recent advances in computational power and sensor technology, large-scale aquifer characterization using various types of measurements has been a promising approach to achieve high-resolution subsurface images. However, large scale inversion requires high, often prohibitive, computational costs associated with a number of large-scale coupled numerical simulation runs and large dense matrix multiplications. As a result, traditional inversion techniques have limited utility for problems that require fine discretization of large domains and a large number of measurements to capture small-scale heterogeneity, like CO2 monitoring in the subsurface. In this work, we apply the principal component geostatistical approach (PCGA), an efficient inversion method, for large-scale aquifer characterization. The domain considered is a synthetic three-dimensional deep saline aquifer intended for CO2 storage with 24,000 unknown permeability grid blocks. Transient pressure and heat tracer measurements from multiple dipole pumping tests are simulated with the TOUGH2 simulator and are used to estimate the heterogeneous permeability field and the corresponding uncertainty. For this scenario, we investigate the worth of combining heat and pumping tracer data for characterization. We demonstrate that with the PCGA, the inversion can be performed at a reasonable computational cost, while also resolving the main features of the permeability field. This presents opportunities for using inverse modeling to improve monitoring design and data collection strategies in field applications.
Monitoring methods and designs for evaluating bioretention performance
Amanda Cording, Stephanie Hurley, and David Whitney
Journal of Environmental Engineering – 143(12):05017006-1-05017006-10 (2017)
Roadside bioretention systems, also known as green streets are becoming increasingly popular, and have widespread potential to reduce pollutant loads coming from road runoff. However, the installation of these systems is outpacing the research regarding the comparative effectiveness of specific design features. Monitoring is a required component of many stormwater regulatory programs, and can provide vital feedback to designers and engineers, lower costs, and determine long-term effectiveness and maintenance requirements, yet very few bioretention systems are monitored. For professionals that are interested in performance assessment, there are very few descriptions of monitoring infrastructure for small drainage areas that are detailed enough to replicate during new bioretention construction projects. This research describes the innovative infrastructure used at the University of Vermont (UVM) Bioretention Laboratory to accurately measure pollutant mass load reduction by roadside bioretention systems. The inflow and outflow monitoring infrastructure designs are provided in enough detail to be adapted and/or replicated in other field settings. The steps taken to integrate the infrastructure into new construction are also provided. Ninety degree v-notch and compound weirs were installed at the inflow and outflow of eight bioretention systems, respectively. Differential pressure transducers related water height to flow rate. A time-based discrete sampling methodology was tested and found to adequately sample multiple points throughout the inflow and outflow hydrographs. This allowed for the comparison of pollutant mass removal among different bioretention designs on an equal volume basis.
Implications of climate change on water budgets and reservoir water harvesting of Nuuanu area watersheds, Oahu, Hawaii
Olkeba Tolessa Leta, Aly I. El-Kadi, and Henrietta Dulai
Journal of Water Resources Planning and Management – 143(11):05017013-01-05017013-19 (2017)
Assessing freshwater availability under changing climate and land-use conditions is critical for tropical islands, where small watershed sizes and unique hydrological features mean that freshwater resources are very sensitive to these changes. The objective of this study is to assess the impact of climate change on the water budgets of the Nuuanu area watersheds (NAW), Oahu, Hawaii, and most importantly, on the potential of water harvesting from Nuuanu Reservoir 4 (NR4). The harvest approach concerns water diversion from the reservoir for artificially supplementing groundwater recharge through injection into the subsurface. Following calibration and validation at multiple streamflow gauging stations across the watershed, the soil and water assessment tool (SWAT) model was applied to assess current and future water availability in the NR4. Multiple statistical evaluation criteria were used to demonstrate that SWAT adequately reproduced the observed daily streamflow hydrographs at all stations. Climate change analyses used the representative concentration pathways (RCP) 4.5 and 8.5 scenarios. The reported analysis suggests that the water-budget components of the NAW will generally be adversely affected by climate change. Compared to the baseline of 35 years, the amount of water available from the NR4 for harvesting will decrease by as much as 27%, and the corresponding outflow values will decrease by as much as 37%. Despite future temperature increases, the actual monthly watershed-scale evapotranspiration will decrease because of the overall decrease in rainfall and soil-moisture availability. Rainfall has the dominant control over the magnitude of water-budget components and harvesting compared with temperature and solar radiation. This study presents a blueprint for surface-water-harvesting scenarios, which may become a necessity across the Pacific and other islands in the future.
Multiple lines of evidence to identify sewage as the cause of water quality impairment in an urbanized tropical watershed
Marek Kirs, Veljo Kisand, Mayee Wong, Robeto A. Caffaro-Filho, Philip Moravcik, Valerie J. Harwood, Bunnie Yoneyama, and Roger S. Fujioka
Water Research – 116:23-33, (2017)
Indicator bacteria, which are conventionally used to evaluate recreational water quality, can originate from various non-human enteric and extra-enteric sources, hence they may not be indicative of human health risk nor do they provide information on the sources of contamination. In this study we utilized traditional (enterococci and Escherichia coli) and alternative (Clostridium perfringens) indicator bacteria, F+-specific coliphage, molecular markers for microorganisms associated with human sewage (human-associated Bacteroides and polyomaviruses), and microbial community analysis tools (16S rRNA gene fragment amplicon sequencing), to identify and evaluate human sewage-related impact in the Manoa watershed in Honolulu, Hawaii. Elevated concentrations of enterococci (geometric mean ranging from 1604 to 2575 CFU 100 mL-1) and C. perfringens (45-77 CFU 100 mL-1) indicated impairment of the urbanized section of the stream, while indicator bacteria concentrations decreased downstream in the tidally influenced Ala Wai Canal. The threshold values triggering water quality violation notifications in Hawaii were exceeded in 33.3-75.0% of samples collected at sites in the urbanized section of Manoa Stream, but were not exceeded in any of the samples collected at an upstream site located in a forested area. Correlation between indicator bacteria concentrations and rainfall amounts was weak to moderate but significant (E. coli R = 0.251, P = 0.009; enterococci R = 0.369, P < 0.001; C. perfringens R = 0.343, P < 0.001), while concentrations of human fecal-associated molecular markers were not significantly correlated with rainfall (human-associated Bacteroides, R = 0.131, P = 0.256; human-associated polyomaviruses, R = 0.213, P = 0.464). Presence of human sewage was confirmed by detection of human-associated Bacteroides and human polyomavirus in the urbanized section of Manoa Stream (83.3-100% and 41.7-66.7% positive samples respectively). It was further confirmed by microbial community analyses which suggested that an average 2.4-3.4% of the total bacterial population in this section was associated with sewage. Microbial community profiles were significantly influenced by rainfall (R2 = 0.4390, P < 0.001), pH (R2 = 0.3077, P = 0.006), salinity (R2 = 0.2614, P = 0.038), and conductivity (R2 = 0.2676, P = 0.031). Although microbial diversity fluctuated throughout the watershed, it was lower in the impaired section. Leaking sewer systems and illegal cross-connections are implicated in the impairment of the watershed, hence both the sewer and the storm water lines should be routinely inspected. Collectively, our data suggest that information derived from the analysis of microbial communities complements current marker-based microbial source tracking techniques and environmental monitoring programs.
Source partitioning of anthropogenic groundwater nitrogen in a mixed-use landscape, Tutuila, American Samoa
Christopher K. Shuler, Aly I. El-Kadi, Henrietta Dulai, Craig R. Glenn, and Joseph Fackrell
Hydrogeology Journal (2017)
This study presents a modeling framework for quantifying human impacts and for partitioning the sources of contamination related to water quality in the mixed-use landscapes of small tropical volcanic islands. On Tutuila, the main island of American Samoa, production wells in the most populated region (the Tafuna-Leone Plain) produce most of the island’s drinking water. However, much of this water has been deemed unsafe to drink since 2009. Tutuila has three predominant anthropogenic non-point groundwater pollution sources of concern: on-site disposal systems (OSDS), agricultural chemicals, and pig manure. These sources are broadly distributed throughout the landscape and are located near many drinking-water wells. Water quality analyses show a link between elevated levels of total dissolved groundwater nitrogen (TN) and areas with high non-point-source pollution density, suggesting that TN can be used as a tracer of groundwater contamination from these sources. The modeling framework used in this study integrates land-use information, hydrological data, and water quality analyses with nitrogen loading and transport models. The approach utilizes a numerical groundwater flow model, a nitrogen-loading model, and a multi-species contaminant transport model. Nitrogen from each source is modeled as an independent component in order to trace the impact from individual land-use activities. Model results are calibrated and validated with dissolved groundwater TN concentrations and inorganic δ15N values, respectively. Results indicate that OSDS contribute significantly more TN to Tutuila’s aquifers than other sources, and thus should be prioritized in future water quality management efforts.
Rainwater harvesting in American Samoa: Current practices and indicative health risks
Marek Kirs, Philip Moravcik, Pradip Gyawali, Kerry Hamilton, Veljo Kisand, Ian Gurr, Christopher Shuler, and Warish Ahmed
Environmental Science and Pollution Research – 24:12384-12392 (2017)
Roof-harvested rainwater (RHRW) is an important alternative source of water that many island communities can use for drinking and other domestic purposes when groundwater and/or surface water sources are contaminated, limited, or simply not available. The aim of this pilot-scale study was to investigate current RHRW practices in American Samoa (AS) and to evaluate and compare the quality of water from common potable water sources including RHRW stored in tanks, untreated stream water, untreated municipal well water, and treated municipal tap water samples. Samples were analyzed using culture-based methods, quantitative polymerase chain reaction (qPCR), and 16S amplicon sequencing-based methods. Based on indicator bacteria (total coliform and Escherichia coli) concentrations, the quality of RHRW was slightly lower than well and chlorinated tap water but exceeded that of untreated stream water. Although no Giardia or Leptospira spp. were detected in any of the RHRW samples, 86% of the samples were positive for Cryptosporidium spp. All stream water samples tested positive for Cryptosporidium spp. Opportunistic pathogens (Pseudomonas aeruginosa and Mycobacterium intracellulare) were also detected in the RHRW samples (71 and 21% positive samples, respectively). Several potentially pathogenic genera of bacteria were also detected in RHRW by amplicon sequencing. Each RHRW system was characterized by distinct microbial communities, 77% of operational taxonomic units (OTUs) were detected only in a single tank, and no OTU was shared by all the tanks. Risk of water-borne illness increased in the following order: chlorinated tap water/well water < RHRW< stream water. Frequent detection of opportunistic pathogens indicates that RHRW should be treated before use. Stakeholder education on RHRW system design options as well as on importance of regular cleaning and proper management techniques could improve the quality of the RHRW in AS.
Assessment of climate change impacts on water balance components of Heeia watershed in Hawaii
Olkeba Tolessa Leta, Aly I. El-Kadi, Henrietta Dulai, and Kariem A. Ghazal
Hydrological models are useful tools for assessing the impact of climate change in watersheds. We evaluated the applicability of the Soil and Water Assessment Tool (SWAT) model in a case study of Heeia, Pacific-island watershed that has highly permeable volcanic soils and suffers from hydrological data scarcity. Applicability of the model was enhanced with several modifications to reflect unique watershed characteristics. The calibrated model was then used to assess the impact of rainfall, temperature, and CO2 concentration changes on the water balance of the watershed. New hydrological insights for the study region: Compared to continental watersheds, the Heeia watershed showed high rainfall initial abstraction due to high initial infiltration capacity of the soils. The simulated and observed streamflows generally showed a good agreement and satisfactory model performance demonstrating the applicability of SWAT for small island watersheds with large topographic, precipitation, and land-use gradients. The study also demonstrates methods to resolve data scarcity issues. Predicted climate change scenarios showed that the decrease in rainfall during wet season and marginal increase in dry season are the main factors for the overall decrease in water balance components. Specifically, the groundwater flow component may consistently decrease by as much as 15% due to predicted rainfall and temperature changes by 2100, which may have serious implications on groundwater availability in the watershed.
Human-associated Bacteroides spp. and human polyomaviruses as microbial source tracking markers in Hawaii
Marek Kirs, Roberto A. Caffaro-Filho, Mayee Wong, Valerie J. Harwood, Philip Moravcik, and Roger S. Fujioka
Identification of sources of fecal contaminants is needed to (i) determine the health risk associated with recreational water use, and (ii) implement appropriate management practices to mitigate this risk and protect the environment. This study evaluated human-associated Bacteroides spp. (HF183TaqMan) and human polyomavirus (HPyV) markers for host sensitivity and specificity using human and animal fecal samples collected in Hawaii. The decay rates of those markers and indicator bacteria were identified in marine and freshwater microcosms exposed and not exposed to sunlight, followed by field testing of the usability of the molecular markers. Both markers were strongly associated with sewage, although the cross-reactivity of the HF183TaqMan (also present in 82% of canine [n = 11], 30% of mongoose [n = 10], and 10% of feline samples [n = 10]) needs to be considered. Concentrations of HF183TaqMan in human fecal samples exceeded those in cross-reactive animals at least 1,000-fold. In the absence of sunlight, the decay rates of both markers were comparable to the die-off rates of enterococci in experimental fresh and marine water microcosms. However, in sunlight, the decay rates of both markers were significantly lower than the decay rate of enterococci. While both markers have their individual limitations in terms of sensitivity and specificity, these limitations can be mitigated by using both markers simultaneously; ergo, this study supports the concurrent use of HF183TaqMan and HPyV markers for the detection of sewage contamination in coastal and inland waters in Hawaii.
Partitioning evapotranspiration into soil evaporation and canopy transpiration via a two-source variational data assimilation system
Tongren Xu, Sayed M. Bateni, Steven A. Margulis, Lisheng Song, Shaomin Liu, and Ziwei Xu
The primary objective of this study is to assess the accuracy of the two-source variational data assimilation (TVDA) system for partitioning evapotranspiration (ET) into soil evaporation (ETS) and canopy transpiration (ETC). Its secondary aim is to compare performance of the TVDA system with the commonly used two-source surface energy balance (TSEB) method. A combination of eddy-covariance-based ET observations and stable-isotope-based measurements of the ratio of evaporation and transpiration to total evapotranspiration (ETS/ET and ETC/ET) over an irrigated cropland site (the so-called Daman site) in the middle reach of the Heihe River basin (northwestern China) was used to investigate these objectives. The results indicate that the TVDA method predicts ETS and ETC more accurately than TSEB. Root-mean-square errors (RMSEs) of midday (1300–1500 LT) averaged soil and canopy latent heat flux (LES and LEC) estimates from TVDA are 23.1 and 133.0 W m-2, respectively. Corresponding RMSE values from TSEB are 41.9 and 156.0 W m-2. Compared to TSEB, the TVDA method takes advantage of all of the information in land surface temperature observations in the estimation period by leveraging a dynamic model (the heat diffusion equation) and thus can generate more accurate LES and LEC estimates.
U.S. recreational water quality criteria: A vision for the future
Roger S. Fujioka, Helena M. Solo-Gabriele, Muruleedhara N. Byappanahalli, and Marek Kirs
This manuscript evaluates the U.S. Recreational Water Quality Criteria (RWQC) of 2012, based upon discussions during a conference held 11–13 March 2013, in Honolulu, Hawaii. The RWQC of 2012 did not meet expectations among the research community because key recommended studies were not completed, new data to assess risks to bathers exposed to non-point sources of fecal indicator bacteria (FIB) were not developed, and the 2012 RWQC did not show marked improvements in strategies for assessing health risks for bathers using all types of recreational waters. The development of the 2012 RWQC was limited in scope because the epidemiologic studies at beach sites were restricted to beaches with point sources of pollution and water samples were monitored for only enterococci. The vision for the future is development of effective RWQC guidelines based on epidemiologic and quantitative microbial risk assessment (QMRA) studies for sewage specific markers, as well as human enteric pathogens so that health risks for bathers at all recreational waters can be determined. The 2012 RWQC introduced a program for states and tribes to develop site-specific water quality criteria, and in theory this approach can be used to address the limitations associated with the measurements of the traditional FIB.
Estimating turbulent heat fluxes with a weak-constraint data assimilation scheme: A case study (HiWATER-MUSOEXE)
Tongren Xu, S. Mohyddin Bateni, and Shunlin Liang
A weak-constraint variational data assimilation (WC-VDA) scheme was developed to estimate turbulent heat fluxes by assimilating sequences of land surface temperature measurements. In contrast to the commonly used strong-constraint VDA system, the WC-VDA approach accounts for the effects of structural and model errors and generates better results. This is achieved by adding a model error term (?) to the surface energy balance equation. The WC-VDA model was tested at two sites with very distinct hydrological and vegetated conditions: the Daman site (a wet site located in an oasis area and covered by seeded corn) and the Huazhaizi site (a dry site located in a desert area and covered by sparse grass). The two sites represent typical desert–oasis landscapes in the middle reaches of the Heihe River Basin, northwestern China. The results proved that the WC-VDA method performed well over very dry and wet conditions, and the estimated sensible and latent heat fluxes agree well with eddy covariance measurements.
Coupled estimation of surface heat fluxes and vegetation dynamics from remotely sensed land surface temperature and fraction of photosynthetically active radiation
S.M. Bateni, D. Entekhabi, S. Margulis, F. Castelli, and L. Kergoat
Remotely sensed Land Surface Temperature (LST) and Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) are assimilated, respectively, into the Surface Energy Balance (SEB) equation and a Vegetation Dynamics Model (VDM) in order to estimate surface fluxes and vegetation dynamics. The problem is posed in terms of three unknown and dimensionless parameters: (1) neutral bulk heat transfer coefficient, which scales the sum of turbulent heat fluxes, (2) soil and canopy evaporative fractions that characterize partitioning among the turbulent heat fluxes over soil and vegetation, and (3) specific leaf area, which captures seasonal phenology and vegetation dynamics. The model is applied over the Gourma site in Mali, the northern region of the West African Monsoon (WAM) domain. The application of the model over the Gourma site shows that spaceborne LST observations can be used to constrain the SEB equation and obtain its key two unknown parameters (i.e., neutral bulk heat transfer coefficient and evaporative fraction). We demonstrate that the spatial patterns of estimated neutral bulk heat transfer coefficient and evaporative fraction resemble, respectively, those of independently observed vegetation index and soil moisture. The framework also yields estimates of surface energy balance components. The daily sensible, latent, and ground heat flux estimates at the Agoufou site that is located in the south of the Gourma region have, respectively, a root-mean-square error (RMSE) of 53.6, 34.4, and 45.1 Wm-2. The daily sensible heat flux estimates at the Bamba site, which is located in the north of the Gourma domain, have a RMSE of 42.6 Wm-2. The results also show that remotely sensed FPAR observations can constrain the VDM and retrieve its main unknown parameter (specific leaf area) over large-scale domains without costly in situ measurements. The results indicate that the estimated specific leaf area values vary reasonably with the expected influential environmental variables such as precipitation, air temperature, and solar radiation. Assimilating FPAR observations into the VDM can also provide an estimate of Leaf Area Index (LAI) dynamics. The estimated LAI values are comparable in magnitude, spatial pattern and temporal evolution with satellite retrievals.
Estimation of surface turbulent heat fluxes via variational assimilation of sequences of land surface temperatures from geostationary operational environmental satellites
Tongren Xu, S.M. Bateni, S. Liang, D. Entekhabi, and Kebiao Mao
Recently, a number of studies have focused on estimating surface turbulent heat fluxes via assimilation of sequences of land surface temperature (LST) observations into variational data assimilation (VDA) schemes. Using the full heat diffusion equation as a constraint, the surface energy balance equation can be solved via assimilation of sequences of LST within a VDA framework. However, the VDA methods have been tested only in limited field sites that span only a few climate and land use types. Hence, in this study, combined-source (CS) and dual-source (DS) VDA schemes are tested extensively over six FluxNet sites with different vegetation covers (grassland, cropland, and forest) and climate conditions. The CS model groups the soil and canopy together as a single source and does not consider their different contributions to the total turbulent heat fluxes, while the DS model considers them to be different sources. LST data retrieved from the Geostationary Operational Environmental Satellites are assimilated into these two VDA schemes. Sensible and latent heat flux estimates from the CS and DS models are compared with the corresponding measurements from flux tower stations. The results indicate that the performance of both models at dry, lightly vegetated sites is better than that at wet, densely vegetated sites. Additionally, the DS model outperforms the CS model at all sites, implying that the DS scheme is more reliable and can characterize the underlying physics of the problem better.
Fate of selected pharmaceutically active compounds during simulated riverbank filtration
Matteo D’Alessio, Bunnie Yoneyama, and Chittaranjan Ray
The objective of this study was to investigate the effect of temperature, oxygen, and organic matter on the removal of selected pharmaceutically active compounds (PhACs) during simulated riverbank filtration (RBF). The behavior of six PhACs (caffeine, carbamazepine, 17-ß estradiol [E2], estrone [E1], gemfibrozil, and phenazone) was evaluated by small flow-through column experiments. Results from our study showed that RBF can be used to treat many of the PhACs found in environmental waters. Local conditions at the RBF site, however, can affect the removal of PhACs and should be investigated. Biodegradation and sorption represented the predominant mechanisms involved during the removal of the selected PhACs. All selected PhACs showed limited and slower removal during the winter. Phenazone was highly impacted by the level of oxygen; complete depletion of phenazone below the analytical limit occurred only under aerobic conditions (dissolved oxygen >8 mg L-1). Caffeine and E2 were highly impacted by the presence of humic acid in the feed water. Caffeine and E2 were depleted below the detection limit in the presence of humic acid regardless of the temperature and the level of oxygen. E1 was impacted by the different environmental conditions and depletion below the detection limit occurred only during the summer under aerobic conditions. Carbamazepine (10%) and gemfibrozil (<30%) showed limited removal regardless of the different levels of temperature, oxygen and humic acid.
Pharmaceutically active compounds: Their removal during slow sand filtration and their impact on slow sand filtration bacterial removal
Matteo D’Alessio, Bunnie Yoneyama, Marek Kirs, Veljo Kisand, Chittaranjan Ray
Slow sand filtration (SSF) has been widely used as a means of providing potable water due to its efficacy, low cost, and minimal maintenance. Advances in analytical instrumentation have revealed the occurrence of pharmaceutically active compounds (PhACs) in surface water as well as in groundwater. It is unclear if the presence of these compounds in the feed water can interfere with the performances of an SSF unit. The aim of this work was to examine i) the ability of two SSF units to remove six PhACs (caffeine, carbamazepine, 17-ß estradiol [E2], estrone [E1], gemfibrozil, and phenazone), and ii) the impact of these PhACs on the removal of bacteria by two SSF units. The presence of PhACs in feed water for SSF can occur in surface waters impacted by wastewater or leakage from sewers and septic tanks, as well as in developing countries where unregulated use and improper disposal are prevalent. Two pilot-scale SSF units were used during the study. Unit B1 was fed with stream water with 1% of primary effluent added, while unit B2 was fed with stream water alone. Although limited removal (<10%) of carbamazepine, gemfibrozil, and phenazone occurred, the complete removal of caffeine, and the partial removal (11–92%) of E2 and E1 were observed in the two SSF units. The results of this study suggest that the occurrence of the selected PhACs, probably estrogens and caffeine, in the feed water at 50 µg L-1 affected the ability of the schmutzdecke to remove total coliform and Escherichia coli. The bacterial removal achieved within the schmutzdecke dropped from 95% to less than 20% by the end of the study. This decrease in removal may be related to the change in the microbial community within the schmutzdecke. A diverse microbial community, including Bacteroidetes and several classes of Proteobacteria, was replaced by a microbial community in which Gammaproteobacteria was the predominant phylum (99%). Despite the low removal achieved within the schmutzdecke, removal of total coliform and E. coli greater than 99% occurred after both SSF units throughout the study. Bacterial removal occurred in the upper half of the sand filter. This was probably due to a diverse microbial community established in the packing material, in which Bacteroidetes (13–25%), Acidobacteria (7–17%) and several classes of Proteobacteria (35–52%) (Alpha-, Beta-, Delta-, and Gammaproteobacteria) were the predominant phyla.
A new species and two new records of Cirratulidae (Annelida: Polychaeta) from Guam, Mariana Islands
Wagner F. Magalhaes and Julie H. Bailey-Brock
Polychaetes from the Mariana Islands of Guam and Saipan have been characterized in previous studies but a thorough taxonomic study of the cirratulids has only been possible recently. Here we report on two new records, Caulleriella pacifica and Chaetozone flagellifera, and a new species, Monticellina lueldredgei, sp. nov. The species C. pacifica is newly recorded for the western Pacific while C. flagellifera is reported for the first time since its original description. The new species M. lueldredgei is unique in the genus with respect to the ultrastructure and segmental origin of the modified capillaries as well as for the distinctive methyl green staining pattern.
Polychaete assemblages associated with the invasive green alga Avrainvillea amadelpha and surrounding bare sediment patches in Hawai‘i
Wagner F. Magalhaes and Julie H. Bailey-Brock
Fauveliopsid polychaetes have been collected at dredge disposal sites off Honolulu from 397–507 m depth. We report and describe the first Pacific record of Laubieriopsis cf. cabiochi (Amoureux, 1982), originally described from the North Atlantic. A new species, Laubieriopsis petersenae, n. sp. is described as being the species in the genus with the lowest num-ber of body segments (15). Other distinctive features are the presence of bidentate aciculars on thoracic chaetigers, and unpaired genital papilla present on the right side of chaetiger 6/7. The new species is most similar to the L. brevis complex from the Atlantic and L. hartmanae and L. brevis japonica from the Pacific Ocean, but differs on the combination of the characters cited above. We provide an emended diagnosis for this genus to include the ultrastructure of the acicular with rows of spines, and a key to all described species.
Polychaete assemblages associated with the invasive green alga Avrainvillea amadelpha and surrounding bare sediment patches in Hawai‘i
Wagner F. Magalhaes and Julie H. Bailey-Brock
Avrainvillea amadelpha is one of the most widespread invasive green algae on Hawai‘i’s reefs, but virtually nothing is known about its associated fauna. A total of 16 sampling stations were selected: ten stations were distributed in areas where the invasive alga occurred abundantly (‘A’ stations) and six stations were placed on bare sand patches (‘S’ stations). Three replicates of ~475 cm³ each were collected in March 2010 at each station, by hand, using a nalgene corer (11 cm in diameter by 5 cm deep). Based on the comparison between Avrainvillea amadelpha-dominated bottoms and the surrounding bare sediment patches, our study demonstrates that these habitats support a diverse and abundant polychaete assemblage, with 2621 individuals and 84 species collected. The species Sphaerosyllis densopapillata (34.14%), Phyllochaetopterus verrilli (8.32%), Protocirrineris mascaratus (5.9%), Exogone longicornis (4.9%) and Syllis cornuta (4.47%) are the dominant taxa. The non-metric multidimensional scaling clearly separated the ‘A’ stations from the ‘S’ stations. ANOSIM has shown that stations within the a priori-defined group ‘A’ are significantly dissimilar from the stations in the group ‘S’ (R = 0.527; P = 0.1%). SIMPER analysis has confirmed the slight but greater dissimilarity between algae and sediment stations (average dissimilarity = 60.12) than within either algae (52.27) or sediment stations (52.04). The invasive green alga A. amadelpha facilitates the development of above-ground polychaete communities, but the negative effects of this invader on the infaunal communities should be further investigated.
A new species and two new records of Poecilochaetus (Polychaeta: Poecilochaetidae) from Hawaii
Wagner F. Magalhaes, Julie H. Bailey-Brock and Cinthya S.G. Santos
A new species, Poecilochaetus anterospinus sp. nov., is described from the east and south shores of Oahu, Hawaii. Poecilochaetus anterospinus sp. nov. is unique in the genus by the presence of noto- and neuropodial spines from chaetiger 11 to posterior segments. Neuropodial spines on anterior chaetigers are absent in all other Poecilochaetus species while notopodial spines are limited to segments preceding the pygidium. Poecilochaetus cf. koshikiensis, originally described from Japan, is newly recorded from Hawaii and apparently widely distributed in the western Pacific and South-east Asian Seas. Poecilochaetus sp. is distinguished from the other two species by the distribution of the ampullaceous cirri (7–12) and its chaetal characters.
Multisection Transmission Line Scatter Function Theory for Measurements of Soil Dielectric Properties
Xiufu Shuai, Timothy R. Green, Chittaranjan Ray, Vassilis L. Syrmos
Vector network analyzers measure both reflection (S11) and transmission (S21) functions, but S21 has not been used to estimate soil dielectric permittivity independently. The objectives of this study were to (i) derive the mathematical model for S21 of a multisection transmission line and (ii) test this model and demonstrate the method. The mathematical model for S21 integrates multiple transmissions across a section as a feedback subsystem. Two experiments were conducted using oven-dried sand and air to examine the S21 model. In the first experiment, a waveguide was filled with one section of sand to form a three-section transmission line; in the second experiment, two sections of sand formed a five-section transmission line. The S11 and S21 functions were measured with a vector network analyzer, and the complex dielectric permittivity values were calculated. Results of Debye model fitting and sensitivity analysis demonstrated that the complex dielectric permittivity of low-loss sand estimated from the measured S21 were less variable and followed the Debye model more closely than those from the measured S11 in the frequency range from 45.0 MHz to 3.0 GHz. Therefore, the complex dielectric permittivity of low-loss materials may be estimated more precisely using measurements of S21 with the derived feedback model than with the widely used method based on S11 . These general behaviors are also expected for more lossy media within a limited frequency range, but the present theory and testing methods should be used to evaluate permittivity measurements under field conditions in moist heterogeneous soils.
Fate and Transport of Selected Estrogen Compounds in Hawaii Soils: Effect of Soil Type and Maropores
Matteo D’Alessio, Dharni Vasudevan, Joesph Lichwa, Sanjay K. Mohanty, Chittaranjan Ray
The fate and transport of estrogen compounds in the environment is of increasing concern due to their potential impact on freshwater organisms, ecosystems and human health. The behavior of these compounds in batch experiments suggests low mobility, while field studies indicate persistence of estrogen compounds in the soil with the possibility of migration to surface water as well as groundwater. To better understand the movement of these chemicals through soils, we examined their transport in three different Hawaiian soils and two aqueous matrices. The three different soils used were an Oxisol, a Mollisol and a cinder, characterized by different mineralogical properties and collected at depths of 60–90 cm and 210–240 cm. Two liquid matrices were used; deionized (DI) water containing calcium chloride (CaCl2), and recycled water collected from a wastewater treatment facility. The experiments were conducted in packed and structured columns. Non-equilibrium conditions were observed during the study, especially in the structured soil. This is believed to be primarily related to the presence of macropores in the soil. The presence of macropores resulted in reduced contact time between soil and estrogens, which facilitated their transport. We found that the organic carbon content and mineralogical composition of the soils had a profound effect on the transport of the estrogens The mobility of estrone (E1) and 17β-estradiol (E2) was greater in cinder than in the other soils. In column experiments with recycled water, earlier breakthrough peaks and longer tails of estrogens were produced compared to those observed using DI water. The use of recycled water for agricultural purposes and the siting of septic tanks and cesspools should be critically reviewed in light of these findings, especially in areas where groundwater is the primary source of potable water, such as Hawaii.
Evaluation of Stream Reaeration Capacity Based on Field Diurnal Dissolved Oxygen Data
Clark C.K. Liu, Pengzhi Lin, Hong Xiao, Xianghua Zhang, Baicang Liu, Yong Zhang and Lei San
Atmospheric reaeration is the interface transfer of oxygen from air to water when the dissolved oxygen (DO) content in the water is below its saturation level. In water quality modeling, river reaeration coefficient has been estimated either by using predictive formulas or by the field method. Predictive formulas were derived by considering the effects of stream turbulence on the interface transfer of oxygen. The field method requires the injection of conservative gas tracer into the stream and then measures the rate of decrease of tracer gas concentration downstream. These two approaches have their limitations: the reaeration coefficients of a stream segment estimated by using different predictive formulas often differ appreciably, while the field method is too expensive to implement. The diurnal DO variation of a stream segment is caused by primary production of plants photosynthesis and respiration, as well as reaeration. Therefore, stream reaeration of can be determined with observed diurnal DO variation and bioproductivity. In this study, a new alternative predictive formula was derived which calculates the reaeration coefficient of a stream based on observed diurnal DO variation. This new predictive formula was tested with data collected in a field water quality survey conducted in Canadaigua Outlet in Upstate New York.
Spatio-temporal changes in trophic categories of infaunal polychaetes near the four wastewater ocean outfalls on Oahu, Hawaii
Xiufu Shuai, Julie H. Bailey-Brock, David T. Lin
This study examines the effect of sewage discharge on benthic polychaete assemblages in the context of their functional trophic categories. We present data spanning 20 years of monitoring benthic invertebrate assemblages and sediment properties at all 4 primary- and secondary-treatment wastewater outfalls servicing Honolulu and the island of Oahu, Hawaii, USA. Samples collected within mandated zones of initial dilution (ZIDs) near outfall discharge sites were compared to samples collected at reference stations at varying distances away. Our ?ndings indicate that sediment properties were not affected by the outfall discharge rate or distance from each ZID. The number of polychaete species in 4 functional trophic categories (carnivore, detritivore, omnivore, and suspension feeder) did not change with the outfall solid loading rate or with distance from each ZID, thus sug- gesting relatively little organic enrichment. We ?nd no evidence of heavy organic enrichment beyond the designated ZIDs at these 4 wastewater outfalls.
Mobility of 2-amino-4,6-dinitrobenzoic acid, a Photodegradation Product of TNT in a Tropical Soil under Saturated Abiotic Conditions
Lukas D. Sheild, Joseph Lichwa, Edwin J. Colona, Philip Moravcik, Chittaranjan Ray
We examined the mobility of 2-amino-4,6-dinitrobenzoic acid (2-A-4,6-DBA) a common photodegradation product of TNT, in soil taken from a former military training area on Oahu Island, Hawaii, USA. 2-A-4,6-DBA is stable and polar and has the potential to migrate to groundwater. Little experimentation has been conducted on explosives in tropical soils which differ chemically from soils intemperate climates. 2,4,6-Trinitrotoluene (TNT) and 1,3,5-hexahydro-1,3,5-trinitrotriazine (RDX) are the most commonly used secondary military explosives. Composition B (Comp B) is a frequently used 59/40/1 combination of RDX, TNT, and wax binder. In order to examine the effect of the presence of Comp B and its degradation products on the mobility of 2-A-4,6-DBA in soil, we dissolved field-collected Comp B fragments in water, exposed the solution to light and pumped it through soil and sand-packed stainless steel columns under abiotic saturated conditions. We found that in the presence of a complex mixture of explosives and degradation products, 2-A-4,6-DBA migrated faster than the parent compound (TNT) and other degradation products through both tropical soil and Ottawa sand (used as a reference) under sterile saturated conditions. The relatively rapid movement of 2-A-4,6-DBA suggests that it has the potential to contaminate underlying groundwater. However, the amount of 2-A-4,6-DBA produced under field conditions and its rate of biotic degradation were not part of this research, therefore, it is unknown how these factors might affect the transport and fate of 2-A-4,6-DBA.
Bioaccessible Arsenic in Soils of Former Sugar Cane Plantations, Island of Hawaii
William G. Cutler, Roger C. Brewer, Aly El-Kadi, Nguyen V. Hue, Patrick G. Niemeyer, John Peard, and Chittaranjan Ray
Arsenical herbicides were used extensively for emergent weed control in Hawaiian sugar cane cultivation from 1913 to about 1950. As a result, surface soil arsenic concentrations average 280 mg kgâˆ’1 across more than 60 km2 of former sugar plantation land in the eastern portion of the Island of Hawaii. This study was conducted to elucidate the relationship between soil properties and arsenic bioaccessibility in the iron-rich volcanic soils. Soils are predominantly Andisols, formed by weathering of basaltic lava and tephra, with pedogenic solid phases consisting of short-range order iron oxyhydroxides, allophane-like aluminosilicates, and metal-humus compounds. These reactive solid phases strongly adsorb oxyanions, such as phosphate and arsenite/arsenate. High arsenic sorption capacity limits desorption and vertical migration within the soil column and prevents contamination of the underlying groundwater aquifer, despite high arsenic loading and precipitation rates. In vitro arsenic bioaccessibility, as measured by the SBRC gastric-phase test, ranges from 2% to 35% and averages 9% of total arsenic. Bioaccessible arsenic is higher in less weathered soils (Udifolists, Typic and Lithic Hydrudands) and lower in more weathered ash-dominant soils (Acrudoxic Hydrudands). Soil weathering indicators, such as reactive iron content, are strong predictors of arsenic bioaccessibility. Based on evidence from soil mineralogy, geochemistry and arsenic speciation, as well as limited soil arsenic bioavailability/bioaccessibility comparisons, risks to human health from direct contact (soil ingestion) are significantly reduced by low arsenic bioaccessibility. Nonetheless, some soils within former sugar cane cultivation areas contain bioaccessible arsenic concentrations exceeding Hawaii Department of Health risk-based action levels, and will require mitigating actions. Even higher levels of soil arsenic contamination have been identified at former pesticide storage and mixing areas, but are generally of localized extent.
Bitentaculate Cirratulidae (Annelida: Polychaeta) from the Northwestern Pacific Islands with Description of Nine New Species
Julie H. Bailey-Brock and Wagner F. Magalhaes
Thirteen cirratulid species from the Hawaiian, Mariana and Marshall Islands are described. Nine species are new to science: Aphelochaeta arizonae sp. nov., Aphelochaeta honouliuli sp. nov., Caulleriella cordiformia sp. nov., Chaetozone michellae sp. nov., Chaetozone ronaldi sp. nov., Monticellina anterobranchiata sp. nov., Monticellina hanaumaensis sp. nov., and Tharyx tumulosa sp. nov., from Oahu, Hawaii and Aphelochaeta saipanensis sp. nov., from Saipan in the Mariana Islands. Dodecaceria fewkesi and Monticellina nr. cryptica are newly recorded from the Hawaiian Islands. Dodecaceria laddi is widely distributed in the western Pacific and material collected from the Hawaiian, Mariana and Marshall islands is described. We provide SEM photographs for all species in addition to line drawings and methyl green staining pattern photographs for the new species.
New records of Hydroides (Polychaeta: Serpulidae) from Guam, Mariana Islands
Julie H. Bailey-Brock and Wagner F. Magalhaes
The genus Hydroides Gunnerus, 1768 is the most species rich serpulid genus with 89 valid species (ten Hove & Kupriyanova, 2009). The Hydroides species from the Western Atlantic and Eastern Pacific (including Hawaii) have been taxonomically revised by Bastida-Zavala & ten Hove (2002, 2003), but species from the most diverse region (Indo-Pacific) are still understudied. Most of the Hydroides are readily distinguished by opercula structures; otherwise they are very similar morphologically with exception of a few species with more than 7 thoracic chaetigers (i.e. Hydroides bisectus Imajima & ten Hove, 1989 and Hydroides sp. 2 sensu Bastida-Zavala & ten Hove, 2003). Hydroides perezi is the only Hydroides species previously recorded in checklists of Marshallese polychaetes (Bailey-Brock, 1999, 2003), but detailed description of this species in Guam is lacking. We provide descriptions and scanning electron microscopy (SEM) photographs of opercula and chaetae of H. perezi from Pago Bay in addition to two new records H. albiceps and H. bannerorum from Apra Harbor, Guam.
The Development of a Renewable-Energy-Driven Reverse Osmosis System for Water Desalination and Aquaculture Production
Clark C.K. Liu
Water and energy are closely linked natural resources – the transportation, treatment, and distribution of water depends on low-cost energy; while power generation requires large volumes of water. Seawater desalination is a mature technology for increasing freshwater supply, but it is essentially a trade of energy for freshwater and is not a viable solution for regions where both water and energy are in short supply. This paper discusses the development and application of a renewable-energy-driven reverse osmosis (RO) system for water desalination and the treatment and reuse of aquaculture wastewater. The system consists of (1) a wind-driven pumping subsystem, (2) a pressure-driven RO membrane desalination subsystem, and (3) a solar-driven feedback control module. The results of the pilot experiments indicated that the system, operated under wind speeds of 3 m s-1 or higher, can be used for brackish water desalination by reducing the salinity of feedwater with total dissolved solids (TDS) of over 3 000 mg L-1 to product water or permeate with a TDS of 200 mg L-1 or less. Results of the pilot experiments also indicated that the system can remove up to 97% of the nitrogenous wastes from the fish pond effluent and can recover and reuse up to 56% of the freshwater supply for fish pond operation.
Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA
Kolja Rotzoll & Stephen B. Gingerich & John W. Jenson & Aly I. El-Kadi
Tidal-signal attenuations are analyzed to compute hydraulic diffusivities and estimate regional hydraulic conductivities of the Northern Guam Lens Aquifer, Territory of Guam (Pacific Ocean), USA. The results indicate a signi?cant tidal-damping effect at the coastal boundary. Hydraulic diffusivities computed using a simple analytical solution for well responses to tidal forcings near the periphery of the island are two orders of magnitude lower than for wells in the islands interior. Based on assigned specific yields of ~0.010.4, estimated hydraulic conductivities are ~20800 m/day for peripheral wells, and ~2,00090,000 m/day for interior wells. The lower conductivity of the peripheral rocks relative to the interior rocks may best be explained by the effects of karst evolution: (1) dissolutional enhancement of horizontal hydraulic conductivity in the interior; (2) case-hardening and concurrent reduction of local hydraulic conductivity in the cliffs and steeply inclined rocks of the periphery; and (3) the stronger in?uence of higher-conductivity regional-scale features in the interior relative to the periphery. A simple numerical model calibrated with measured water levels and tidal response estimates values for hydraulic conductivity and storage parameters consistent with the analytical solution. The study demonstrates how simple techniques can be useful for characterizing regional aquifer properties.
Seawater Intrusion and Sustainable Yield of Basal Aquifers
Clark C.K. Liu and John J. Dai
Basal aquifers, in which freshwater floats on top of saltwater, are the major freshwater supply for the Hawaiian Islands, as well as many other coastal regions around the world. Under unexploited or natural conditions, freshwater and the underlying seawater are separated by a relatively sharp interface located below mean sea level at a depth of about 40 times the hydraulic head. With forced draft, the hydraulic head of a basal aquifer would decline and the sharp interface would move up. It is a serious problem of seawater intrusion as huge amounts of freshwater storage is replaced by saltwater. Also, with forced draft, the sharp interface is replaced by a transition zone in which the salinity increases downward from freshwater to saltwater. As pumping continues, the transition zone expands. The desirable source-water salinity in Hawaii is about 2% of the seawater salinity. Therefore, the transition zone expansion is another serious problem of seawater intrusion. In this study, a robust analytical groundwater flow and salinity transport model (RAM2) was developed. RAM2 has a simple mathematical structure and its model parameters can be determined satisfactorily with the available field monitoring data. The usefulness of RAM2 as a viable management tool for coastal ground water management is demonstrated by applying it to determine the sustainable yield of the Pearl Harbor aquifer, a principal water supply source in Hawaii.
Capitellidae Grube, 1862 (Annelida: Polychaeta) from the Hawaiian Islands with description of two new species
Wagner F. Magalhaes and Julie H. Bailey-Brock
A survey of the capitellids from the Hawaiian Islands has yielded 16 species in seven genera, most represent new records and two species are newly described, Notodasus dasybranchoides sp. nov. and Scyphoproctus edmondsoni sp. nov. The species Capitella minima, Capitellethus cinctus and Scyphoproctus pullielloides are the most common and widely distributed capitellids in Hawaii, present in subtidal sediments surrounding outfall diffusers and also at reference locations. The species Mediomastus californiensis and Capitella giardi may have been introduced to Oahu from different sources, the former is abundant in soft sediments of Honolulu and Pearl Harbors and the latter is found associated with commercial oysters in muddy ponds. The genera Branchiocapitella and Pulliella are considered herein as synonyms of Capitella and Scyphoproctus, respectively. This paper is the first comprehensive study of the Hawaiian capitellids and all species are described and illustrated with line drawings, color and SEM photographs. A key to all 16 capitellid species found in shallow waters from the main Hawaiian islands is provided.
A new species of Protocirrineris (Polychaeta: Cirratulidae) from Hawaii including a redescription of the New Zealand Protocirrineris nuchalis
Wagner F. Magalhaes and JH Bailey-Brock
Protocirrineris mascaratus sp. nov., is described from intertidal reef flats in Oahu, Hawaii. It is 10 unique among its congeners by the segmental origin of the feeding tentacles and branchiae in addition to the very distinct methyl green staining pattern on the anterior end. A redescription of Protocirrineris nuchalis based on syntypes and a comparative table of all valid species within Protocirrineris is presented.
Lacydonia quadrioculata, a new lacydoniid (Polychaeta: Phyllodocida) from Oahu, Hawaii
Wagner F. Magalhaes, Julie H. Bailey-Brock and Alexandra E. Rizzo
A new species of the genus Lacydonia is described from shallow waters off Oahu, Hawaii. This species is unique among its congeners by the presence of two pairs of small eyes; other lacydoniids may have either one pair of large or small eyes or no eyes at all. The description of Lacydonia quadrioculata sp. nov., brings the number of valid species within Lacydonia to 10 but the taxonomy of this genus is still confusing as most species are very similar morphologically and the majority of the descriptions are based merely on the single type or very few specimens. We discuss the relevance of some taxonomic characters used in species-level descriptions and provide a comparative table with selected characters of all valid species.
Glyceridae (Annelida: Polychaeta) from Guam, Mariana Islands with description of a new species of Glycera Savigny in Lamarck, 1818
Wagner F. Magalhaes and Alexandra E. Rizzo
Glycera juliae sp. nov., is described from shallow water sediments within Apra Harbor, Guam, Mariana Islands. This species is characterized by the presence of ailerons with rounded triangular base; proboscideal papillae of type 1 mainly digitiform with straight, median, longitudinal ridge and type 2 shorter and broader, oval to globular, without ridges; two slender triangular to digitiform prechaetal lobes, notopodial lobe slightly shorter than neuropodial lobe, two short postchaetal lobes, rounded anteriorly with posterior notopodial lobe becoming sub-triangular and longer than rounded neuropodial lobe; branchiae present, retractile, simple digitiform attached medially on anterior side of parapodia and a dark brown pigmentation forming transverse bands on prostomium and body segments. It is most similar to Glycera nicobarica and G. macintoshi by the shape of parapodial structures but also shares similarities with Glycera sphyrabrancha, G. branchiopoda, G. guatemalensis, G. semibranchiopoda and G. southeastatlantica by the shape and types of proboscidial papillae, differing on the shape of the ailerons, parapodial lobes and presence of branchiae. The occurrence of Glycera tesselata is confirmed for Guam and specimens are described and illustrated with SEM photographs.
Adsorption, transport and degradation of fipronil termiticide in three Hawaii soils
Xiufu Shuai, Jingyu Chen and Chittaranjan Ray
BACKGROUND: The behavior of the termiticide fipronil in soils was studied to assess its potential to contaminate ground and surface water. This study characterizes (1) adsorption of fipronil in three different soils, (2) transport of fipronil through leaching and runoff under simulated rainfall in these soils and (3) degradation of fipronil to fipronil sulfide and fipronil sulfone in these soils.
RESULTS: The adsorption experiments showed a Freundlich isotherm for fipronil with Koc equal to 1184 L kg-1. In the leaching experiments, the concentration of fipronil and its metabolites in leachate and runoff decreased asymptotically with time. The concentration of fipronil in the leachate from the three soils correlated inversely with soil organic carbon content. The degradation experiment showed that the half-life of fipronil in the soils ranged from 28 to 34 days when soil moisture content was 75% of field capacities, and that 10.723.5% of the degraded fipronil was transformed into the two metabolites (fipronil sulfide and fipronil sulfone).
CONCLUSION: Fipronil showed large losses through leaching but small losses via runoff owing to low volumes of runoff water generated and/or negligible particle-facilitated transport of fipronil. The half-life values of fipronil in all three soils were similar.
Predicting soil phosphorus fertilizer rate using hierarchical segmented regression models
Xiufu Shuai, Russell S. Yost, and T. Jot Smyth
Predicting soil phosphorus (P) needs and P fertilizer requirements is important for plant nutrition and reducing environmental risk. The P requirement (PR) can be calculated from three components: the current status of soil P (P0), soil P buffer coefficient (PBC), and the soil P critical level (PCL). The PBC and PCL can be predicted from soil clay content using linear-plateau models. The PR, PBC, and PCL form a hierarchical model because PR depends on PBC and PCL, which, in turn, depend on soil clay content. The objective of this study is to estimate the parameters in this hierarchical model to ensure reasonable performance and behavior of PR in a large range of soil clay contents. Results showed that the linear-plateau model described the change of PBC with soil clay content in the range of 39 to 760 g kg-1. This model also described the change of PCL with soil clay content in the range of 80 to 760 g kg-1 for six crops, including cotton, cowpea, maize, peanut, soybean, and wheat. The obtained PR showed irregular behavior of PR within soil clay content range from 288 to 357 g kg-1 when PBC and PCL were independently predicted from soil clay. When the join points in the linear-plateau models of PBC and PCL were set to be equal, the irregular change of PR with soil clay content disappeared. The hierarchically modeled system predicts a decrease in PR with increasing current status of soil P and a curve-plateau trend with soil clay content.
Kinetics of ion-pair formation on variable-charge minerals using the frequency domain method
Xiufu Shuai and Russell S. Yost
Predicting nutrient behavior is ever more critical to understanding and management of the environment, particularly in highly weathered and tropical environments. The fate of nutrients in the environment seems heavily influenced by the kinetics of ion-pair formation on the surfaces of variable-charge minerals coupled with transport processes. The objective of this study was to generate the coupled processes in column experiments and estimate the reaction rates using the frequency domain method. Columns were packed with ground natural minerals (gibbsite, goethite, and hematite). The input signals were designed as a sinusoidal change in NaNO3 concentration within 0.1 and 0.2 mmol L-1 and constant pH 4.0, and the highest frequency of the input signals was 0.714 min-1. The input and output signals of NO3- and H+ concentrations were monitored by ultravioletvisible light and pH detectors, respectively. A mathematical model was derived to describe the diffusion process of a counterion from aqueous solution to plane, the recombinationdissociation reaction between a charged surface site and the counterion, and the coupled transport process described by the convectiondispersion equation. Results showed that the output signals were dominated by the designed frequency and thus the coupled processes were linear. The aqueous H+ concentration changed linearly with that of the aqueous NO3- concentration. The mathematical model fit the measured transfer function of the processes. The estimated rates of recombination of ion pairs were 52.0, 30.5, and 8.0 L mol-1 min-1, and the estimated rates of dissociation of the ion pair were 0.189, 0.256, and 0.285 min-1 for the natural gibbsite, goethite, and hematite, respectively.
A new species of Sphaerephesia (Polychaeta: Sphaerodoridae) from Mamala Bay, south shore of Oahu, Hawaii
Wagner F. Magalhaes, Julie H. Bailey-Brock, And Brendan M. Barrett
A new species of Sphaerephesia is described from Mamala Bay, south shore of Oahu, Hawaii. Sphaerephesia mamalaensisStandards based on fecal indicator bacteria (FIB) have traditionally been used by the U.S. Environmental Protection Agency to determine when recreational waters are contaminated by fecal and sewage inputs. Studies in tropical and subtropical areas, however, have shown that these same standards cannot reliably be used in these environments to determine when waters are contaminated by sewage. This is because soil, sediments, water, and plants have been shown to be significant indigenous sources of FIB in tropical/subtropical climates. In these climates, alternative fecal indicators, such as Clostridium perfringens and F+RNA coliphages, may be more reliable markers of sewage contamination, because these organisms are generally found in low concentrations in the environment. In the State of Hawaii, monitoring data relating to FIB (fecal coliform, Escherichia coli, enterococci) and alternative indicator microorganisms (C. perfringens, F+RNA) in recreational waters has been obtained for the Island of Oahu, but similar data are lacking for other islands within the state. The major goal of this study was to monitor water samples obtained from the Nawiliwili watershed on the Island of Kauai for traditional FIB (fecal coliform and enterococci) as well as alternative fecal microbial indicators (C. perfringens, somatic coliphages, and F+RNA coliphages). Results for FIB concentrations on the Island of Kauai followed a similar trend as data obtained from the Island of Oahu. In addition, in areas like the Island of Kauai where cesspools are prevalent, monitoring for F+RNA and somatic coliphages may provide more reliable data in the detection of subsurface contamination of streams by cesspool waste, which can then lead to the pollution of coastal waters. Finally, genotyping of F+RNA phages obtained from the study sites provided additional evidence that human cesspool contamination was occurring within the Nawiliwili watershed.
A new species of Acrocirrus (Polychaeta: Acrocirridae) from Coconut Island, Oahu, Hawaii
Wagner F. Magalhaes and Julie H. Bailey-Brock
A new species of Acrocirrus is described from shallow waters of Coconut Island in Kaneohe Bay, Oahu, Hawaii. Acrocirrus bansei sp. nov. is an Acrocirrus whose segment 13 (chaetiger 11) is modified and equipped with a heavy neuropodial acicular hook. This new species is most similar to A. frontifilis based on the presence of notopodial cirri, which have been, up to now, a unique feature of A. frontifilis. The species differ most notably by the absence of the notopodial cirri on the posterior chaetigers.
Potential for riverbank filtration in India
Cornelius Sandhu, Thomas Grischek, Pradeep Kumar, and Chittaranjan Ray
Riverbank filtration (RBF) has been used for many decades in Europe and the United States to provide drinking water to communities located on riverbanks. In India, the development of RBF has the potential to provide drinking water to many cities located on the Ganga Plains currently using surface water as a source for their public water supply. Water diversion for irrigation and discharge of wastewater to rivers with extremely low flows has aggravated the water supply situation for many Indian cities using surface water. A number of Indian cities, with source waters of significantly varying quality, are already using RBF. In most of these cities no significant additional treatment is provided to the filtrate for their water supply. The objective of this article is to examine selected operating bank filtration sites in India (that have been investigated since 2005) and to elucidate additional potential RBF sites based on water problems and hydrogeologic suitability. A summary of selected operational RBF systems in Ahmedabad, Delhi, Haridwar, Mathura, Medinipur and Kharagpur, Nainital, Patna and Srinagar and their ability to produce potable water is provided. Analysis of the suitability of RBF for Allahabad, Bhubaneswar, Guwahati, and Vijayawada, based on hydrogeology and land use, is also provided.
On the genus Raphidrilus Monticelli, 1910 (Polychaeta: Ctenodrilidae) with description of two new species
Wagner F. Magalhaes, Julie H. Bailey Brock, and Jennifer S. Davenport
Raphidrilus harperi sp. nov., is described from the Gulf Intracoastal Waterway (GIWW) in Venice, Florida from sediments consisting of coarse sands and shell hash. Raphidrilus hawaiiensis sp. nov., is described from Oahus shallow waters and inhabits a successful invasive alga in Waikiki and sandy sediments adjacent to ocean outfalls in Barbers Point and Sand Island, off Honolulu. The genus Raphidrilus is emended, the distinctness between the genera Raricirrus and Raphidrilusis confirmed and keys to all recognized genera of Ctenodrilidae and species of Raphidrilus are given.
Comparison of transport and attachment behaviors of Cryptosporidium parvum oocysts and oocyst-sized microspheres being advected through three minerologically different granular porous media
Arvind Mohanram, Chittaranjan Ray, Ronald W. Harvey, David W. Metge, Joseph N. Ryan, Jon Chorover, and D.D. Eberl
In order to gain more information about the fate of Cryptosporidium parvum oocysts in tropical volcanic soils, the transport and attachment behaviors of oocysts and oocyst-sized polystyrene microspheres were studied in the presence of two soils. These soils were chosen because of their differing chemical and physical properties, i.e., an organic-rich (43-46% by mass) volcanic ash-derived soil from the island of Hawaii, and a red, iron (22-29% by mass), aluminum (29-45% by mass), and clay-rich (68-76% by mass) volcanic soil from the island of Oahu. A third agricultural soil, an organic- (13% by mass) and quartzrich (40% by mass) soil from Illinois, was included for reference. In 10-cm long flowthrough columns, oocysts and microspheres advecting through the red volcanic soil were almost completely (98% and 99%) immobilized. The modest breakthrough resulted from preferential flow-path structure inadvertently created by soil-particle aggregation during the re-wetting process. Although a high (99%) removal of oocysts and microsphere within the volcanic ash soil occurred initially, further examination revealed that transport was merely retarded because of highly reversible interactions with grain surfaces. Judging from the slope of the substantive and protracted tail of the breakthrough curve for the 1.8-mm microspheres, almost all (>99%) predictably would be recovered within ~4000 pore volumes. This suggests that once contaminated, the volcanic ash soil could serve as a reservoir for subsequent contamination of groundwater, at least for pathogens of similar size or smaller. Because of the highly reversible nature of organic colloid immobilization in this soil type, C. parvum could contaminate surface water should overland flow during heavy precipitation events pick up near-surface grains to which they are attached. Surprisingly, oocyst and microsphere attachment to the reference soil from Illinois appeared to be at least as sensitive to changes in pH as was observed for the red, metaloxide rich soil from Oahu. In contrast, colloidal attachment in the organic-rich, volcanic ash soil was relatively insensitive to changes in pH in spite of the high iron content. Given the fundamental differences in transport behavior of oocyst-sized colloids within the two volcanic soils of similar origin, agricultural practices modified to lessen C. parvum contamination of ground or surface water would necessitate taking the individual soil properties into account.
Udotea argentea (Bryopsidales: Udoteacea), a new record for the Hawaiian Islands
Julie H. Bailey-Brock and Wagner F. Magalhaes
Udotea argentea, a broadly distributed Indo-Pacific seaweed, has been collected for the first time on the south coast of Oahu, Hawaii. The habit and anatomical features are illustrated and the possible ecological impact to the native benthic community is discussed.
Protodrilidae (Annelida: Polychaeta) from the Hawaiian Islands and Comparison with Specimens from French Polynesia
Julie H. Bailey-Brock, Claude Jouin-Toulmond, and Richard E. Brock
Three species of Protodrilidae were collected from the islands of O’ahu and Ni’ihau in the Hawaiian chain, including specimens closely resembling Parenterodrilus taenioides ( Jouin, 1979), described from Mo’orea (French Polynesia). Others are probably an undescribed species of Parenterodrilus that was found in fine sand substrate collected off Wai’anae, O’ahu. A third species, Protodrilus albicans Jouin, 1970, described from Banyuls-sur-Mer (Mediterranean Sea) and recorded from Mo’orea and Tahiti as well, was also collected from O’ahu. Depths and habitat characteristics are given for these new records to the Hawaiian fauna. It is suggested that the wide geographical distribution of the different ”cosmopolitan species” of Protodrilidae is related both to the dispersal by free-swimming larvae and to the ancient origin of this interstitial fauna.
Changes of freshwater-lens thickness in basaltic island aquifers overlain by thick coastal sediments
Kolja Rotzoll, Delwyn S. Oki, Aly I. El-Kadi
Freshwater-lens thickness and long-term changes in freshwater volume in coastal aquifers are commonly assessed through repeated measurement of salinity profiles from monitor wells that penetrate into underlying salt water. In Hawaii, the thickest measured freshwater lens is currently 262 m in dike-free, volcanicrock aquifers that are overlain by thick coastal sediments. The midpoint depth (depth where salinity is 50% salt water) between freshwater and salt water can serve as an indicator for freshwater thickness. Most measured midpoints have risen over the past 40 years, indicating a shrinking lens. The mean rate of rise of the midpoint from 19992009 varied locally, with faster rates in highly developed areas (1.0 m/year) and slower rates in less developed areas (0.5 m/year). The thinning of the freshwater lenses is the result of long-term groundwater withdrawal and reduced recharge. Freshwater/salt-water interface locations predicted from measured water levels and the Ghyben-Herzberg principle may be deeper than measured midpoints during some periods and shallower during other periods, although depths may differ up to 100 m in some cases. Moreover, changes in the midpoint are slower than changes in water level. Thus, water levels may not be a reliable indicator of the amount of freshwater in a coastal aquifer.
Proton Charge and Adsorption of Humic Acid and Phosphate on Goethite
Xiufu Shuai, Gladis Zinat
Little information is available about the changes of the proton charge of goethite in the presence of phosphate (P) and humic acid (HA). The objectives of this study were to systematically measure the proton charge of the ternary mixture and adsorption of HA and P on goethite. The potentiometric titration method was used to measure proton charges in single, binary, and ternary mixtures of goethite, HA, and P as a function of pH and ionic strengths. Results showed that proton charge in the ternary mixture became more negative with increasing pH and the loadings of HA and P. Th e point of zero charge (PZC) decreased linearly with the initial concentrations of HA and P. At low to intermediate pH, little variation was observed in adsorption of P on goethite in the presence of HA. A small reduction in the adsorption of P in the presence of HA was observed when compared with the control (without HA loading) at high pH. In 2008, Weng et al. developed a model describing the electrostatic interaction between HA and P at the 1-plane of the compact part of the electrical double layer (EDL). In this study, Weng et al.’s model was used to interpret the eff ect of adsorbed HA on the adsorption of P on goethite as well as the nonsignificant interaction of PZC between HA and P.
Abbreviations: EDL, electrical double layer; FA, fulvic acid; HA; humic acid; P, phosphate; PPZC, pristine point of zero charge; PZC, point of zero charge; PZSE, point of zero salt eff ect.
Bank filtration as managed surface groundwater interaction
Thomas Grischek, Chittaranjan Ray
Riverbank Filtration (RBF) is a managed surface-groundwater interaction process where surface water is induced to flow to pumping wells installed on the banks of rivers and lakes. We present the surface-groundwater interaction issues at various geomorphologic settings, from the headwaters of a river to its confluence with the oceans/lakes. In each reach, the factors for the sustainable operation of RBF systems are discussed. Siting of wells with respect to the river/lake, scouring and clogging of the river beds and the resulting impacts on pollutant removal, managing the wells during floods, and RBF at other settings have been addressed.
Reference to this paper should be made as follows: Grischek, T. and Ray, C. (2009) ‘Bank filtration as managed surface groundwater interaction’, Int. J. Water, Vol. 5, No. 2, pp.125139
Fate and transport of TNT, RDX, and HMX in streambed sediments: Implications for riverbank filtration
Weixi Zheng, Joseph Lichwa, Matteo D’Alessio, Chittaranjan Ray
Riverbank filtration (RBF) refers to the process of capturing surface water passing through the river-sediment- aquifer system by using a collection technique such as a well or an infiltration gallery. RBF removes nearly all suspended and a large number of dissolved contaminants from the surface water. Therefore, it can function as an effective pretreatment process in drinking-water production. TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane), and HMX (1,3,5,7-tetranitro- 1,3,5,7-tetrazocane) are three military explosive chemicals that are considered of concern to human health when present in source waters. This study is to evaluate the ability of the filtration media in RBF systems to remove these chemicals. The results from an anoxic batch test showed that all three chemicals will degrade while passing through streambed sediments. The pseudo first-order degradation- rate constants for TNT, RDX, and HMX were measured to be 0.33, 0.055, and 0.033 d1, respectively. Under aerobic conditions only TNT showed significant degradation. Results from a model RBF system showed that the mobility of the three chemical contaminants in streambed sediments was in the order: HMX > RDX > TNT. The results suggest that RBF is capable of removing TNT and RDX but HMX levels may continue to be of concernespecially when collector wells use laterals running directly beneath the stream or riverbed.
Reducing the Complexity of Inverse Analysis of Time Domain Reflectometry Waveforms
Xiufu Shuai, Ole Wendroth, Caicheng Lu, and Chittaranjan Ray
Inverse analysis of time domain refl ectometry (TDR) waveform in the frequency domain is important in measuring complex dielectric permittivity of soils. However, for widely used probes designed as impedance mismatching and nonseparable connection between probe head and coaxial cable, none of the available models can be used for the inverse analysis. The objective of this study was to derive a model which is applicable for this specifi c type of probes. A two-section (probe head and probe rods) model was derived from the full model of Feng et al. (1999) by reducing its complexity on the basis of the matching design of cable tester and coaxial cable. The model was validated by comparison of the measured spectra of properly terminated coaxial cable with the theoretical values, and the accuracy of the model was studied by the comparison of the estimated complex dielectric permittivity of ethanol by the model with those measured by the network analyzer method. This model was applied to a silt loam soil under different levels of water content and electrical conductivity (EC). The results showed that the two-section model was applicable for this specifi c type of probes to measure complex dielectric permittivity at low frequency range. The lowest frequency of 30 MHz was used to estimate soil complex dielectric permittivity. The real parts of the estimated soil dielectric permittivity were close to the apparent dielectric permittivity determined by travel time analysis (TTA). The soil bulk EC calculated from the imaginary parts of the estimated soil dielectric permittivity was close to the measured values.
Use of Artificial Neural Networks for Predicting of Groundwater Contamination
Sahoo, Goloka Behari, and Chittaranjan Ray.
Artificial neural networks are empirical mathematical tools proven to represent complex relationships of hydrological systems. Neural networks are increasingly being applied in subsurface modeling where intricate physical processes and lack of detailed field data prevail. Two types of ANN models: Back propagation neural network (BPNN) and radial basis function neural network (RBFN) are examined to predict the pesticide contamination of domestic wells. Because sample collection, analysis, and re-sampling are expensive, a large dataset is not available for ANN use in this study. This study presents analyzes of raw data for preparation of input subsets for ANN use. Thus, a clustering technique is used to divide the whole dataset into three subsets: training, validating, and testing. The sensitivity analysis was carried out by deleting one or more input variables from the input data set to measure the importance of one variable over the other in terms of ANN prediction performance. It provides a sense of the effect of each parameter on pesticide occurrence in a well. The well depth, depth to aquifer material from land surface, and on-site pesticide storage are found to be important parameters in pesticide occurrence in well.
Flow Forecasting Using Artificial Neural Network and a Distributed Hydrological Model, MIKE SHE
Sahoo, Goloka Behari, and Chittaranjan Ray.
Many drainage basins in Hawaii, especially those on Oahu, are highly urbanized with large areas of impervious surface that produce nearly 100% runoff. Streamflows change by a factor of 60 in only 15 minutes during flashfloods, because these streams are short and steep and respond quickly to intense tropical storms. No matter how small is the scale, many tropical storms on Oahu lead to flash foods and cause life and property damage. Thus, forecasting and analysis of runoff and streamflow in relation to the size and land-use characteristics of individual drainage basins are important for flood and land resources management. This study presents flow estimation of a tropical mountainous stream on Oahu at a 15-minute frequency using a back-propagation neural network (BPNN) and a physically. distributed model MIKE SHE (DHI, 2003). It was found that BPNN was able to predict the streamflow with a correlation coefficient (R) greater than 0.99. It was demonstrated that BPNN was found to be superior to MIKE SHE in terms of predictive performance efficiency: R, mean error, and root mean square error when all information at the gauging stations: stream stage, rainfall, and evapotranspiration was available. MIKE SHE produced continuous and consistent results along the streams (gauged and ungauged locations) with R approximately 0.7. Also, MIKE SHE produced results at multiple sites (i.e. at gauged and ungauged stations) and at multiple scales (e.g., streamflow, groundwater head, surface water level, and soil moisture content). While BPNN is not intended as a substitute for a conceptual model, it can be used as a viable alternative to a physically-distributed model only if streamflows at gauging sites are required. The advantages and limitations of using empirical BPNN and a distributed physical based model for flow forecasting are discussed.
Distribution of discharge intensity along collector well laterals in a model of riverbed filtration.
Kim, Seung-Hyun, Kyu-Hong Ahn, and Chittaranjan Ray
Experiments were performed to evaluate flow and head variations along perforated screens (1030 mm in diameter) using sand tanks which were connected and a perforated screen extended through these tanks to form a model collector well lateral up to 2.6 m in length. Hydraulic heads and discharge along the lateral and production rates of the model collector well were measured as the water level in the well, the lateral length, and diameter, and the hydraulic conductivity of the filter sand were varied. A mathematical model was developed to predict the axial flow velocity distribution and the discharge intensity variation along the lateral using the head distribution. Results showed that the production rate increased as the lateral length and diameter and the drawdown at the well increased. However, the production rate increase was not linearly related to these factors. When larger-diameter laterals were used, the axial flow velocity in the laterals decreased. This caused the hydraulic heads along the lateral to become more flattened, resulting in a lateral of high efficiency in terms of water production. This condition is similar to the assumption of the uniform discharge intensity along the lateral that many researchers have used in the analysis of the horizontal wells. Under the conditions of this study, a critical axial flow velocity was determined to be 1 m/ s. Hydraulic efficiency decreased drastically when the velocity exceeded 1 m/ s. The roughness coefficient (the Manning’s n value) of the lateral varied as a function of factors such as axial velocity and discharge intensity, and it ranged from 0.010 to 0.015.
Microgenetic algorithms and artificial neural networks to assess minimum data requirements for prediction of pesticide concentrations in shallow groundwater on regional scale.
Sahoo, Goloka Behari, and Chittaranjan Ray.
Artificial neural networks (ANNs) have been extensively used for forecasting problems involving water quantity and quality. In most cases, the geometry and model parameters of the ANN are set using a trial-and-error approach to achieve better network generalization ability, whereby the available data are divided arbitrarily into training, testing, and validation subsets. It has been shown that using the arbitrary sample selection method to assign samples into the training subset commonly results in the inclusion of samples from densely clustered regions and omission of samples from sparsely represented regions. This paper presents a systematic approach using the self-organizing map (SOM) clustering technique that identifies which samples and determines how many samples should be included in each of the three subsets required by ANN for optimum predictive performance efficiency. In addition, this paper presents the microgenetic algorithms (mGA) that optimize ANN’s geometry and model parameters in terms of the correlation coefficient (R). In the sensitivity analysis, mGA model parameters are found to be least sensitive to the optimum R value, while ANN’s predictive performance is significantly affected by (1) the poor selection of its geometry and model parameters and (2) the arbitrary selection of samples for the three subsets of data used. It is demonstrated that the mGA-ANN model using the SOM technique for data division outperforms the mGA-ANN model using arbitrary data division. For the training subset, the model using the SOM technique identifies samples that are representative of the region, requiring only 20% of the total samples, whereas the arbitrary sample selection method requires 5090%. Because resampling on a regional scale is expensive and time consuming, substantial cost and time could be saved if resampling could be done only on the 20% representative drinking water wells.
Determination of trifloxystrobin and its metabolites in the tropical soils of Hawaii by ASE-LC/MS/MS
Chen, Jingyu, Chittaranjan Ray, and Binh Loo.
Analytical methods for the determination of trifloxystrobin and four of its metabolites were developed in a leaching study conducted in Hawaii. To duplicate plots at each of five locations representing various agricultural areas in Hawaii, trifloxystrobin was applied at label rates and allowed to leach under normal rain and irrigation conditions. Soil samples were collected at weekly to monthly intervals and the residual concentrations of trifloxystrobin and metabolites measured. A quantitative analytical method for their determination in various soil samples was developed using accelerated solvent extraction (ASE), coupled with liquid chromatography-tandem mass spectrometry. Extraction solvent with various ratios of methanol to water, addition of EDTANa2 to the extract solvent, and ASE cell temperature were adjusted to improve recovery. Deuterated (E,E)-trifloxystrobin was chosen as the internal standard of the analytical method. The limit of quantitation was 2.5 ppb in the soil for trifloxystrobin and its metabolites. Laboratory aerobic degradation studies with the soils from the five sites were also conducted to measure the same compounds.
Land management impacts on coastal watershed hydrology.
Fares, A., and A. I. El-Kadi.
From the Wit Press website: (http://www.compmech.com/acatalog/9781845640910.html) Coastal watersheds differ from others by their unique features, including proximity to the ocean, weather and rainfall patterns, subsurface features, and land covers. Land use changes and competing needs for valuable water and land resources are especially more distinctive to such watersheds. This book covers recent research relevant to coastal watersheds. It addresses the impact of a stream’s chemical, biological, and sediment pollutants on the quality of the receiving waters, such as estuaries, bays, and near-shore waters. The contents of the book can be divided into three sections; a) overview of hydrological modelling, b) water quality assessment, and c) watershed management. This book differs from other hydrology books by dealing with coastal watersheds which are characterized by their unique features: including weather and rainfall patterns, subsurface characteristics, and land use and cover. In addition to academia, the book should be of interest to organizations concerned with watershed management, such as local and federal governments and environmental groups. Overall, the book is expected to satisfy a great need toward understanding and managing critical areas in many parts of the world.
Movement of bromacil in a Hawaii soil under pineapple cultivation – A field study
Alavi, G., M. Sanda, B. Loo, R. E. Green, and C. Ray.
Recent discovery of low concentrations of bromacil in drinking water prompted the State of Hawaii to examine the leaching behavior of bromacil in pineapple fields. This study is a follow up to earlier work on bromacil concentrations in soil profiles in a pineapple field in central Oahu, Hawaii. Soil samples were collected for bromacil analysis at different times prior to and after application from a pineapple field that was previously surveyed by other research workers. The leaching pattern of bromacil was further investigated at two different application rates (2.25 and 1.8 kg ha_1). The concentration of bromacil in the topsoil about 100 days after bromacil application (1.8 kg ha_1) was substantially higher in 2002 compared to 1999. The distribution profiles were generally consistent with the one presented in the previous study. Residual bromacil was present in the entire sampled zone (3 m deep) about 18 months after the previous bromacil application. Over a period of 9 months, there was substantial dissipation of bromacil residue present in the topsoil. The residual concentration of bromacil in the area that received the reduced application rate (1.8 kg ha_1) were lower than those receiving the current application rate (2.25 kg ha_1) and the depth of penetration of the bromacil front was shallower at the reduced application rate. Because of the common practice of placing plastic mulch around the base of the pineapple plants to retain volatile nematicides, the applied bromacil was found to be concentrated in the areas between the plastic mulch, transported by runoff from the plastic. The study results encourage the use of less than the label led rate of application of bromacil for pineapple fields.
Estimating hydraulic properties of coastal aquifers using wave setup.
Rotzoll, K., and Aly I. El-Kadi.
Wave setup is the elevated mean water-table at the coast associated with the momentum transfer of wave breaking, which occurs generally over several days. Groundwater responses to wave setup were observed as far as 5 km inland in central Maui, Hawaii. The analysis showed that at times of energetic swell events wave-driven watertable overheights dominate low-frequency groundwater fluctuations associated with barometric pressure effects. Matching peak frequencies at 1.7 x 10-6 Hz and 3.7 x 10-6 Hz were identified in setup and observed head using spectral decomposition. Similar to tides, the setup propagation through the aquifer shows exponentially decreasing amplitudes and linearly increasing time lags. Due to the longer periods of setup oscillations, the signal propagates deeper into the aquifer (~10 km in central Maui) than diurnal tides (5 km) and can therefore provide information on greater length scales. Hydraulic diffusivity was estimated based on the setup propagation. An effective diffusivity of 2.3 x 107 m2/d is consistent with aquifer parameters based on aquifer tests and tides. A one-dimensional numerical model supports the results of the analytical solution and strengthens the suitability to estimate hydraulic parameters from setup propagation. The methodology is expected to be beneficial to high-permeability coastal environments, such as on volcanic islands and atolls.
Use of dissolved helium as an environmental water tracer.
Richter, F., and A. I. El-Kadi.
Abstract: This study deals with the development, calibration, and testing of an automated technology for using helium as a water tracer in continuous real-time monitoring. The instrument combines a gas extraction system and a helium mass spectrometer. The technology was tested in laboratory pipe, open-water, and porousmedia experiments, and the results were used to test helium breakthrough curves against those for salinity expressed by electrical conductivity. The instrument promptly responds to concentration changes. In general, accurate results were obtained for first arrival times and peaks of solutes, as well as for the dispersive characteristics of the breakthrough curves. The accuracy of the elution curves needs some improvement due to limitations of the helium extraction system. In addition, the developed method is sensitive to the water flow rate and nitrogen pressure used in extracting helium from the solution. These issues can be addressed through calibration. Potential improvements are possible through the use of more precise helium concentration quantification equipment and through enhancement of the extraction method. The success of the methodology makes helium an attractive tracer for use near drinking water sources, in environmentally sensitive areas such as wetlands and fish farms, and near recreational or other areas where esthetics are a concern.
Analysis of an unconfined aquifer subject to asynchronous dual-tide propagation
Aly I. El-Kadi, and Stephen B. Gingerich.
Most published solutions for aquifer responses to ocean tides focus on the one-sided attenuation of the signal as it propagates inland. However, island aquifers experience periodic forcing from the entire coast, which can lead to integrated effects of different tidal signals, especially on narrow high-permeability islands. In general, studies disregard a potential time lag as the tidal wave sweeps around the island. We present a one-dimensional analytical solution to the ground-water flow equation subject to asynchronous and asymmetric oscillating head conditions on opposite boundaries and test it on data from an unconfined volcanic aquifer in Maui. The solution considers sediment-damping effects at the coastline. The response of Maui aquifers indicate that water-table elevations near the center of the aquifer are influenced by a combination of tides from opposite coasts. A better match between the observed ground-water head and the theoretical response can be obtained with the proposed dual-tide solution than with single-sided solutions. Hydraulic diffusivity was estimated to be 2.3 x 107 m2/d. This translates into a hydraulic conductivity of 500 m/d, assuming a specific yield of 0.04 and an aquifer thickness of 1.8 km. A numerical experiment confirmed the hydraulic diffusivity value and showed that the y-intercepts of the modal attenuation and phase differences estimated by regression can approximate damping factors caused by low-permeability units at the boundary.
Estimating hydraulic conductivity from specific capacity for Hawaii aquifers
Aly I. El-Kadi.
Site-specific relationships between specific capacity and hydraulic parameters (transmissivity and hydraulic conductivity) were investigated for volcanic rocks in Maui, Hawaii, USA. Details about well construction were commonly ignored in previous studies. To improve on such efforts, specific-capacity values were normalized by the open interval of the well. Correcting specific capacity for turbulent head losses using step drawdown tests and including aquifer penetration length improved the correlation between specific capacity and hydraulic conductivity and reduced uncertainty in the prediction of hydraulic parameters. The relationships provide estimates of aquifer parameters with correlation coefficients between 0.81 and 0.99. The relationships for Maui can probably be extended to other Hawaii islands, given the similarity of aquifer formations and a reasonable fit to step-drawdown data from Oahu. Hydraulic conductivity was estimated from 1,257 specific-capacity values in the Hawaii’s well database. Hydraulic-conductivity estimates for dike-free volcanic rocks are consistent on different islands. For all islands, the estimates range from 3 to 8,200 m/d, with a geometric-mean and median value of 272 and 291 m/d, respectively. A geostatistical approach was applied to Maui and Oahu to generate island-wide hydraulic-conductivity maps to facilitate groundwater management efforts.
The nature and value of ecosystem services: An overview highlighting hydrologic services.
Brauman, Kate A., Gretchen C. Daily, T. Ka’eo Duarte, and Harold A. Mooney.
A screening tool for vulnerability assessment of pesticide leaching to groundwater for the islands of Hawaii, USA.
Stenemo, Fredrik, Chittaranjan Ray, Russell Yost, and Steven Matsuda.
An evaluation of the mobility of pathogen indicators, Escherichia coli and bacteriophage MS-2, in a highly weathered tropical soil under saturated conditions
Wong, Tiow-Ping, Muruleedhara Byappanahalli, Bunnie Yoneyama, and Chittaranjan Ray.
Evaluation of dual-permeability models for chemical leaching assessment to assist pesticide regulation in Hawaii
Alavi, G., J. Dusek, R. E. Green, and C. Ray.
Groundwater is the primary source of drinking water for all the islands of Hawaii. Past agricultural practices have led to the contamination of groundwater in certain locations. As a result, the state of Hawaii emphasizes the prevention of contamination of groundwater from the leaching of pesticides. Hawaii currently uses a simple (Tier I) screening assessment model to evaluate the leaching potential of pesticides. This model is only capable of indicating if a chemical is likely to leach; it can estimate neither the concentration profile in soil nor the concentration in leachate water. The USEPA is seeking partnership with the state of Hawaii for examining the feasibility of using Tier II models in Hawaii conditions for pesticide registration. Two pesticide leaching models, MACRO 4.3 and S1D DUAL, were tested using leaching data for five pesticides from a field site on the island of Oahu. Despite deficiencies, it is one of the best data sets currently available for tropical soils. Both MACRO 4.3 and S1D DUAL models explicitly include preferential flow components but use different concepts in model formulations. The performances of the two models were generally similar. The results show that preferential flow had a minor role in transporting the chemicals compared with micropore flow because of the high saturated conductivity of micropores (matrix). We conclude that a process-based model will contribute substantially to the evaluation of chemical leaching risk and complement the Tier I model that currently is used for pesticide registration in Hawaii.
Evaluation of enterococcal surface protein genes as markers of sewage contamination in tropical recreational waters
Betancourt, W. Q., and R. S. Fujioka.
A molecular monitoring strategy was developed to detect prevalence of two enterococcal surface protein genes (esp-1 gene and esp-2 gene) in isolates of enterococci from recreational waters in Hawaii as evidence of human sewage contamination. The sensitivity and specificity of the methods were evaluated in selected environmental samples including human sewage, ocean water samples near a sewage outfall, shoreline coastal beach waters, ambient soil samples, and ambient streams not known to be contaminated with sewage. The results of this study show that the esp-1 and esp-2 genes are highly associated with enterococci from sewage sources as compared to non-point sources. Therefore these esp genes show promise as good indicators of sewage contamination. However, more sensitivity and specificity of esp genes are needed. Moreover, a more specific enumeration method for E. faecium and E. faecalis is needed so that subsequent test for the esp genes will be reliable and feasible.
Benthic infaunal communities around two artificial reefs in Mamala Bay, Oahu, Hawaii
Fukunaga, Atsuko and Julie H. Bailey-Brock
Esssential oils of selected Hawaiian plants and associated litters
Chen, Jingyu, Joseph Lichwa, and Chittaranjan Ray.
The chemical composition of the essential oils from the leaves of Araucaria heterophylla (also known as Norfolk Island pine), Casuarina cunninghamian, Eucalyptus citriodora, Psidium cattlenium , var. lucidum (also known as strawberry guava), and litters of the first two species were studied using two gas chromatography techniques, one equipped with a mass spectrometer detector (GC/MS) and the other with a flame ionization detector (GC/FID). Six volatile compounds were identified in the leaf oil of A. heterophylla. A substantial increase in the amount of a-pinene, a-terpinene and a decrease in the amount of (b-caryophyllene was noticed in the litter oil of A. heterophylla. Three volatile compounds were identified in C. cunninghamian. Another monoterpene, a-terpinene, was observed in the litter oil of C. cunninghamian.. Eleven compounds were identified in the leaf oil of P. cattlenium, of which b-caryophyllene (59.0%), a-pinene (13.2%) and myrcene (11.3%) were the major components. Thirteen volatile oil compounds were identified in the E. citriodora leaf oil, of which citronellal (42.8%), citronellol (17.9%) and a-terpinene (11.2%) were the major components.
A mini-review of modeling studies on membrane bioreactor (MBR) treatment for municipal wastewaters
Ng, Aileen N.L. & Albert S. Kim
Membrane bioreactor (MBR) technology is a promising method for water and wastewater treatment because of its ability to produce high-quality effluent that meets water quality regulations. Due to the intrinsic complexity and uncertainty of MBR processes, basic models that can provide a holistic understanding of the technology at a fundamental level are of great necessity. Compared to experimental research and development, followed by commercialization of the technology, modeling studies for system design analysis and performance prediction are at a relatively rudimentary state. In this light, this review was conducted to provide an assessment of present efforts in modeling MBR systems, specifically for municipal wastewater treatment. Models considered in this review are classified into three categories: biomass kinetic models, membrane fouling models, and integrated models with (light) couplings to describe the complete MBR process. The specific features, unique advantages, and capturing capability of experimental observations of each model are discussed and assessed. Crucial components in MBR modeling studies are carefully selected and assessed, based on the importance of their roles in characterizing MBR performance, and future MBR modeling directions are suggested.
Estimating hydraulic proerties of volcanic aquifers using constant-rate and variable-rate aquifer tests
Rotzoll, Kolja, Aly I. El-Kadi, and Stephen B. Gingerich
In recent years the ground-water demand of the population of the island of Maui, Hawaii, has significantly increased. To ensure prudent management of the ground-water resources, an improved understanding of ground-water flow systems is needed. At present, large-scale estimations of aquifer properties are lacking for Maui. Seven analytical methods using constant-rate and variable-rate withdrawals for single wells provide an estimate of hydraulic conductivity and transmissivity for 103 wells in central Maui. Methods based on constantrate tests, although not widely used on Maui, offer reasonable estimates. Step-drawdown tests, which are more abundantly used than other tests, provide similar estimates as constant-rate tests. A numerical model validates the suitability of analytical solutions for step-drawdown tests and additionally provides an estimate of storage parameters. The results show that hydraulic conductivity is log-normally distributed and that for dike-free volcanic rocks it ranges over several orders of magnitude from 1 to 2,500 m/ d. The arithmetic mean, geometric mean, and median values of hydraulic conductivity are respectively 520, 280, and 370 m/ d for basalt and 80, 50, and 30 m/d for sediment. A geostatistical approach using ordinary kriging yields a prediction of hydraulic conductivity on a larger scale. Overall, the results are in agreement with values published for other Hawaiian islands.
Analytical groundwater modeling for estimating sustainable yield of lao Aquifer, Maui, Hawaii.
Liu, C. C. K., and X. Li. 2007.
Since 1980, several numerical models of groundwater flow and salinity transport have been developed for Hawaii basal aquifers. At this time, however, they are too complicated as viable management tools because adequate calibration and verification of these models require extensive field data which are not currently available. In our study, a simple robust analytical model called RAM2 was developed by taking Hawaii basal aquifers as a completely stirred tank reactor. RAM2 consists of (a) a flow submodel and (b) a salt transport submodel which simulates the evolution of the transition zone in a basal freshwater lens. The mathematical structure of RAM2 is simple, such that it can be solved analytically and can be readily calibrated using available field data. Its usefulness as a management tool was demonstrated by applying it in an evaluation of the sustainable yield of the Iao aquifer on Maui, Hawaii.
Modeling streamflows and flood delineation of the 2004 flood disaster, Manoa, Oahu, Hawaii.
El-Kadi, Aly I., and Eric Yamashita.
In October 2004 a flood caused extensive damage to the University of Hawai’i (UH) campus and neighboring residential areas in Mnoa Valley, O’ahu, Hawai’i. This modeling study was aimed at streamflow evaluation and flood delineation for the area impacted by the flood. The study concluded that the HEC-1 model of the U.S. Army Corps of Engineers is suitable for simulating storm runoff response for the study area, considering the nature of small Hawai’i watersheds, which generate hydrographs with steep rising and falling limbs. The curve-number method of the U.S. Soil Conservation Service is also suitable because it predicts reasonably well the main features of streamflow hydrographs, including runoff duration and time of peaks. To improve on accuracy, however, there is a need for better characterization of spatial rainfall distribution through measurements. A flood delineation model, which treats the flood as a hypothetical dam break, was used to predict the floodwater pathway, flood zone extent, maximum flood depth, and the time to reach that depth. The model predicted an upper value for storm total flow volume that would not cause flooding on the UH campus. Although not fully validated, the developed models can guide data-collection and decision-making processes. For example, the models demonstrated that it is possible to mitigate the flood through streamflow diversion and stream dredging, realignment, and lining. For efficient management, we recommend defining a new subwatershed of the Ala Wai basin (to be called the West Mnoa Watershed) that contains the university campus.
A screening tool for vulnerability assessment of pesticide leaching to groundwater for the islands of Hawaii, USA.
Stenemo, Fredrik, Chittaranjan Ray, Russell Yost, and Steven Matsuda.
This paper describes an updated version of a screening tool for groundwater vulnerability assessment to evaluate pesticide leaching to groundwater, based on a revised version of the attenuation factor. The tool has been implemented in a geographical information system (GIS) covering the major islands of the state of Hawaii, USA. The Hawaii Department of Agriculture currently uses the tool in their pesticide evaluation process as a first-tier screening tool. The basic soil properties and pesticide properties necessary to compute the index, and estimates of their uncertainty, are included in the GIS. Uncertainties in soil and pesticide properties are accounted for using first-order uncertainty analysis. Classifications of pesticides as likely, uncertain or unlikely to leach are made on the basis of the uncertainty and a comparison of the revised attenuation factor with values and uncertainties of two reference chemicals. The reference chemicals represent what are considered to be a leachable and a non-leachable pesticide under Hawaii conditions. It is concluded that the tool is suitable for screening new and already used pesticides for the islands of Hawaii. However, the tool is associated with uncertainties that are not accounted for, so a conservative approach with respect to interpretation of the results and selection of pesticide parameters used in the tool is recommended.
Cake resistance of aggregates formed in the diffusion-limited-cluster-aggregation (DLCA) regime.
Kim, Albert S., and Rong Yuan.
The ideal aggregate characterized by the quadratically increasing permeability k(r) = k2r2 is investigated to estimate the specific cake resistance (i.e., inverse permeability) of a cake layer composed of deposited aggregates formed in the diffusion-limited-cluster-aggregation (DLCA) regime. Happel’s cell model is employed in this study by embedding the ideal aggregate in the center of a spherical cell of tangential stress-free surface. The specific resistance is analytically calculated as a function of the occupancy fraction and then compared to those of conventional cake layers of equal-sized spherical colloids and uniformly porous spheres. The DCLA-aggregate cake layer provides significantly less specific resistance and therefore shows the remarkable potential of aggregate-enhanced membrane filtration (AEMF) as a new protocol for colloidal filtration. The settling velocity of a swarm of the ideal aggregates is investigated as a by-product and experimental verification of this theory.
Parameter sensitivity of a hydrocarbon biodegradation model under uncertainty of permeability.
El-Kadi, Aly I.
The effects of permeability variability on uncertainty of the results of a hydrocarbon biodegradation model are addressed. The model includes saturated and unsaturated flow, multi-species transport, heat transport, and bacterial-growth processes. A stochastic approach was used in the uncertainty analysis. Sensitivity analyses were conducted, taking into consideration the effects of heterogeneity. The Monte Carlo method was used, with permeability as the input stochastic variable. Results showed that uncertainty increases with time. This can lead to difficulties regarding cleanup decision making such as predicting the timeframe to reach an aquifer cleanup goal. It was not possible to replace the heterogeneous system with a homogeneous one through the use of effective parameters that preserve an equivalent behavior of the two systems. Effective permeability is space and time dependent and also depends on values of bioactivity parameters. The study also emphasized the importance of accurately measuring certain bacterial parameters, namely, maximum substrate uptake rate for degradation and cell yield coefficient. Uncertainties regarding nutrient and oxygen uptake and saturation parameters were less important for the current application.
Assessment of submarine groundwater discharge by handheld aerial infrared imagery: case study of Kaloko Fishpond and Bay, Hawaii
Duarte, T. Ka’eo , Harold F. Hermond, Donald Frankel, and Sheila Frankel
Handheld aerial infrared imagery was used to infer submarine groundwater discharge (SGD) to a Hawaiian fishpond and adjacent bay at Kaloko, Hawai’i, using heat as a tracer for the relatively cooler groundwater. Use of a handheld infrared camera aboard readily available, unmodified aircraft is a convenient and less expensive alternative to use of a camera mounted in the belly of a customized aircraft, although it favors taking images with an oblique view instead of the preferable nadir view. Pond-wide patterns of SGD were readily apparent in oblique images and were typically more apparent in infrared imagery than in ground truth data, due to the formation of thin (order of cm) surface strata of groundwater which could easily fail to be observed with conventional temperature probes. Absolute temperature measurement is affected by the variation of surface emissivity and reflectivity with angle of camera view; corrections based on use of Fresnel’s equation were of the order of several degrees centigrade at convenient oblique aerial viewing angles. Other factors that may affect apparent water temperature include sky temperature and camera error. Surface waves may also account for variations in average surface emissivity and reflectance that were not accounted for by the aforementioned corrections. Under suitable conditions, handheld aerial infrared imagery revealed spatial patterns of groundwater inflow, detected differences in water temperature at the meter scale, and measured absolute water temperature with accuracy on the order of 2 to 3 C.
The History of Groundwater Management and Research in Hawaii
El Kadi, Aly L., and James E.T. Moncur
This paper reviews groundwater research studies with emphasis on modeling as a tool for management of Hawaii’s resources. Hawaii depends to a great extent on groundwater resources, and concern over availability of potable water has guided research regarding both water quantity and quality. Research is mainly aimed at understanding Hawaii hydrogeology, identifying aquifer parameters and modeling needs, and applying models in the management of resources. Use of models has advanced over the past ten years toward routine aquifer management, yet there is a great need to better characterize aquifer spatial data. Variability of hydrogeological conditions is a major hurdle for successful application of models. This paper also addresses legal, institutional, and economic issues pertinent to Hawaii’s pressing problems regarding water allocation. Areas of critical research needs are also identified.
EPS membrane biofouling in membrane filtration: An analytic modeling study
Kim, Albert S., Huaiqun Chen, Rong Yuan
Biofouling is theoretically investigated by modeling solute transport within a biofilm, defined in this study as a swarm of solid biocolloids surounded by liquid-like exopolymeric substances (EPS). A mathematical approach is employed to map the biofilm to an equivalent, simple speherical cell using a self-consistent method. It is found that the physical presence of EPS’ and their reaction with solute ions reduce the mass transfer coefficient, which significantly contributes to permate flux decline in reverse osmosis and nanofiltration menmbrane proceseses.
Hydraulic permeability of polydispersed cake layers: an analytic approach
Kim, Albert S., Aileen N.L. Ng
An analytic method is introduced to calculate hydraulic permeability of porous media composed ofpolydispersed spheres with log-normal and normal (Gaussian) distributions of particle sizes. From the comparison of the permeability for the two particle-size distributions, it was observed that a medium with normally distributed particle sizes consistently has a lower permeability than a medium with log-normally distributed particle sizes. This phenomenon is due to the larger number of smaller particles in the normal distribution, which results in greater cake resistance. The specific resistance of the cake layer is computed by taking the inverse of the permeability.
A postaudit study of DBCP and EDB contamination in the Pearl Harbor aquifer
Rungvetvuthivitaya, Mongkolaya, Chittaranjan Ray, Richard E. Green
A simulation of the transport of dibromochloropropane (DBCP) and ethylene dibromide (EDB) in the vadose zone and ground water was conducted in the Mililani area of Central Oahu, Hawaii to revisit the groundwater contamination predictions made by researchers at the University of Hawaii in 1988 for selected wells of the Honolulu Board of Water Supply. Examination of sampled DBCP results in these wells indicated a large discrepancy between the observed and predicted concentrations in 1988. Therefore, a post-audit study was initiated in the same area to assist in better defining projected concentrations of contaminants in well waters in the future. With the new data, different modeling approaches were undertaken for simulating flow and contaminant transport in both the vadose and saturated zones. The new simulations indicate travel times of 14 to 32 years for contaminants to reach the water table, depending on the location. The approximate recovery time of wells in the study area is expected to occur after the year 2016 for DBCP. The predicted concentration of EDB in the wells is less than the current detection limit. Variabilities in model predictions due to parameter uncertainties and model limitations are also considered. While the predicted concentrations from the present simulations match sampled data better than the concentrations from earlier modeling efforts, still a number of uncertainties remain.
Determination of hormones and non-ionic surfactant degradation products in small-volume aqueous samples from soil columns using LC-ESI-MS-MS and GC-MS
Chen, J., J. Lichwa, M. Snehota, S. Mohanty, C. Ray
The leaching of two estrogens, 17 beta-estradiol and estrone, and two degradation products of non-ionic surfactants, octylphenol and nonylphenol, through a soil column were studied to estimate their transport behavior. Different concentration methods (lyophilization, solid phase extraction, and liquid-liquid extraction) were evaluated for analyzing these compounds in small effluent fractions (30-50 mL) collected. Liquid chromatography-mass spectrometry (LC-MS-MS) and gas chromatography-mass spectrometry (GC-MS) were employed for quantitative analysis of these compounds. After comparison, the lyophilization LC-MS-MS method was found to be best suited for the analysis of the two estrogen hormones and the liquid-liquid extraction GC-MS method best for the analysis of the two phenols in small samples in the soil column study. Because of their high sorption capacity, these compounds were mostly sorbed in the upper part of the soil column and were difficult to detect in column effluent.
Predicting flux decline in crossflow membranes using artificial neural networks and genetic algorithms
Sahoo, Goloka Behari, Chittaranjan Ray
The geometry and internal parameters of artificial neural networks (ANNs) have significant effects on the prediction performance efficiency of the network. The optimal ANN geometry is problem-dependent. Although some guidance is available in the literature for the choice of geometry and internal parameters, most networks are calibrated using the trial-and-error approach. This paper presents the use of genetic algorithms (GAs) to search the optimal geometry and values of internal parameter of a multilayer feedforward back-propagation neural network (BPNN) and a radial basis function network (RBFN). The prediction performance efficiency of the GA-ANN combination is examined using an already published experimental dataset of crossflow membrane filtration. The data includes the permeate flux decline under various operating conditions (e.g. transmembrane pressure and filtration time) with different physicochemical properties of feed water (e.g. different combinations of three particle diameters, three pH values and four ionic strengths). It is illustrated that the GA-optimized ANN predicts the permeate flux decline more accurately than a network in which the ANN calibration is done using a trial-and-error approach. It is shown that scaling the training data to the range of 0-1 helps the modeler find the solution range of an RBFN for GA.
A wind-driven reverse osmosis system for aquaculture wastewater reuse and nutrient recovery
Sahoo, G.B., C. Ray, E.H. De Carlo
Frequent flash floods of Hawaii streams pose continuous threats to the coastal environment because the streams respond rapidly to high runoff and huge transport quantities of sediments, to which are sorbed nutrients, heavy metals, and persistent hydrophobic organic compounds. High-frequency stream flow and water quality estimation are essential to correctly assess water quality variations and pollutant loads during flash floods, because stream flow and turbidity in Hawaii can change by a factor of 60 and 30, respectively, in 15 min. This study shows the application of artificial neural networks (ANNs) to assess flash floods and their attendant water quality parameters using measured data of a Hawaii stream. The paper illustrates that ANNs predict stream flow with a correlation coefficient (R) greater than 0.99 and turbidity and specific conductance with R-values greater than 0.80. Although the R-values for the estimation of dissolved oxygen, pH, and water temperature were somewhat low, most of the estimated stream water quality values (turbidity, specific conductance, dissolved oxygen, pH, and water temperature) were within the limits of 30% deviations of the 1:1 line. The R-value for the estimation of stream water qualities could have been significantly improved if high resolution (at 15 min or lower measurement frequency), noise-free, and continuous data were available for a longer period of time. The paper demonstrates that the upstream water quality parameters depend on weather forces and land use of the watershed and the downstream water quality parameters additionally influenced by oceanic tides. Stream stage is found to be an important input parameter for stream flow prediction using ANN; however, the predictive performance of ANN for the estimation of stream flow is improved if weather data, rainfall, and evapotranspiration are included in the input data set.
Calibration and validation of a physically distributed hydrological model, MIKE SHE, to predict streamflow at high frequency in a flashy mountainous Hawaii stream
G. B. Sahoo, C. Ray, E. H. De Carlo
Hawaii streams are short and steep, often producing dangerous flash floods as a result of rainfall events that can be short but intense. The streamflow can change by a factor of 60 in only 15 min. Using streamflow data collected at 15-min intervals, the physically distributed modeling system, MIKE SHE, is applied to the Manoa-Palolo stream system on the island of Oahu, Hawaii, to study the watershed response to storm events. Because of the unavailability of detailed spatially distributed data, a single-valued hydraulic conductivity for the saturated zone is used as the representative of the entire watershed. It is shown that a well-calibrated MIKE SHE with the single-valued hydraulic conductivity is able to produce consistent results with correlation coefficients greater than 0.7. The rainfall distribution along the watershed is the driving factor for the estimation of streamflow. The reciprocal of Manning’s roughness coefficient (M) for the watershed and the hydraulic conductivities (vertical and horizontal) of the saturated zone had the most pronounced effects in determining the shape of flood peaks. The peak streamflow is reduced by nearly 1 mp3/s for an M value that was changed from 60 to 10. For the upper part of the watershed, which is located in the rainiest and steepest mountainous area, the horizontal hydraulic conductivity value of the saturated zone is insensitive, while the horizontal and vertical hydraulic conductivity values of the saturated zone are sensitive to predict streamflow for the entire watershed. Drainage depth, an average position of phreatic surface above which the water table in one grid starts to drain to the nearest grid or stream, is less sensitive, while drainage time constant, the time required to discharge the drainage water to the nearest grid or stream, is more sensitive for the estimation of base flow. Because calibration for a large basin at small time steps (e.g., every 15 min) takes a long time to complete a year of simulation, splitting the entire watershed into subwatersheds during calibration was useful in examining the effects of key parameters on streamflow estimation before calibrating the parameters for the entire watershed.
Diffusive tortuosity factor of solid and soft cake layers: A random walk simulation approach
Kim, Albert S., Huaiqun Chen
Diffusive tortuosity factor of solid (colloidal) and soft (biofilm) cake layers formed during membrane filtration is investigated using the random walk simulation of solute tracers. Four different structures are investigated as possible candidate structures of the cake layers: simple cubic (SC), body-centered cubic (BCC), face-centered cubic (FCC), and random colloidal cake (RCC) structures. Low porosity of the deformable, compressible soft cake is mimicked by allowing overlaps among the adjacent particles and taking into account only the void spaces. When the volume fraction of each structure is less than its own maximum packing ratio of mono-dispersed solid spheres, Maxwell’s theoretical prediction of the diffusive tortuosity factor is accurately superimposed on the simulation results, showing structural indifference of the tortuosity factor. However, when the soft cake is compressed so that the volume fraction becomes greater than the maximum packing ratio, the diffusive tortuosity factor surpasses Maxwell’s theory and tends to diverge as the porosity reaches zero. The deviation of simulation results from the theory starts near the maximum packing ratio of each structure, and SC and FCC structures show higher diffusive tortuosity factors in comparison to the BCC structure. Most important, the RCC layer with a realistic irregular configuration has the highest diffusive tortuosity factor over almost the entire range of volume fraction. This implies that the solute diffusion within the soft cake layer of a random irregular structure is most hindered so that the concentration polarization and osmotic pressure of the solutes are accordingly enhanced on the membrane surface.
El Kadi, Aly
An article in “Water Encyclopedia”, ed. Jay Lehr, Jack Keeley, and Janet Lehr, 662-667. John Wiley & Sons, Available online at www.mrw.interscience.wiley.com/eow
Water Management and Water Reuse
Moreland, Victor, Roger Fujioka
Water management is a process for determining a proper blend between demand management and supply augmentation with options that provide a long – term, reliable water supply for all beneficial uses ( best water source use) at a reasonable cost (financial resources best use) and with the highest possible benefits to the water users, economic development, environmental quality, and other perceived society needs.
Drinking water requires a multi – barrier approach to providing proper quality water to protect the public health of our world’s population. The first barrier starts with protecting water sources, both surface waters and groundwaters. This source water protection and the other barriers will be discussed in the text of this paper. Drinking water quality is not required for all uses and source waters should be paired appropriately with needed quality water for its intended use (irrigation does not require potable water).
Even treated wastewaters have beneficial uses for other than drinking purposes as long as appropriate laws, regulations, and government sponsored monitoring and enforcement can provide acceptable public health risk.
Monte Carlo simulation of colloidal membrane filtration: Principal issues for modeling
Jim C. Chen, Albert S. Kim
The principal issues involved in developing a Monte Carlo simulation model of colloidal membrane filtration are investigated in this study. An important object for modeling is the physical dynamics responsible for causing particle deposition and accumulation when encountering an open system with continuous outflow. A periodic boundary condition offers a solution to the problem by recirculating continuous flow back through the system. Scaling to full physical dimensions will allow for release of the model from flawed assumptions such as constant cake layer volume fraction and thickness throughout the system. Furthermore, rigorous modeling on a precise scale extends the model to account for random particle collisions with acute accuracy. A major finding of this study proves that forces within the colloidal filtration system are summed and transferred cumulatively through the inter-particle interactions. The force summation and transfer phenomenon only realizes its true value when the model is scaled to full dimensions. The overall strategy for model development, therefore, entails three stages: first, rigorous modeling on a microscopic scale; next, comprehensive inclusion of relevant physical dynamics; and finally, scaling to full physical dimensions.
A new marine species of Tubificoides (Annelida: Oligochaeta: Tubificidae) from Hawaii, U.S.A.
Christer Erseus, Olav Giere, Jennifer Dreyer, and Julie H. Bailey-Brock
Tubificoides calvescentis is described from subtidal sediments near a sewage outfall at Sand Island, off Honolulu, Oahu, Hawaii. It is characterized by hair chaetae being restricted to preclitellar segments, small atria and sperma-thecae, and smooth, cylindrical, cuticular penis sheaths. Tubificoides bakeri Brink-hurst, 1985, known from the West coast of North America, appears to be closely related to the new species; its male genitalia are virtually identical to those of T. calvescentis. However, T. bakeri does not possess distinct cuticular papillae, which are evident in T. calvescentis, and it has more numerous chaetae and more slender spermatozeugmata than those of the new species. The paper also provides a nomenclaturally updated list of all marine oligochaetes reported from Hawaii.
Bacteroides Spp. as reliable marker of sewage contamination in Hawaii’s environmental waters using molecular techniques
Betancourt, W.Q., and R.S. Fujioka
Comparative stability and growth requirements of S. aureus and faecal indicator bacteria in seawater
Fujioka, R. S. and T. M. Unutoa
The fate (stability, multiplication) of S. aureus, E. coli and E. faecalis was determined in three classes of recreational waters (seawater, estuarine, stream) supplemented with nutrients in the form of sewage and peptone. In the absence of sunlight (242 C), all bacteria in all water samples did not multiply and were slowly (days) inactivated. When 50% sewage was added to all water samples, E. coli and E. faecalis multiplied but S. aureus did not. When peptone (0.05%, 0.5%) was the added nutrient, the three bacteria multiplied. In the presence of sunlight (1527 C), S. aureus was inactivated rapidly (hours) in all water samples. These results show that when their nutritional requirements are met, S. aureus, E. coli and E. faecalis can multiply in the high salinity conditions of seawater. However, under environmental conditions, sunlight is an effective natural bactericidal agent.
Prediction of permeate flux decline in crossflow membrane filtration of colloidal suspension: A radial basis funcion neural network approach
Chen, Huaiqu, and Albert S. Kim
Application of artificial neural networks to assess pesticide contamination in shallow groundwater
Sahoo, Goloka B., Chittaranjan Ray, Edward Mehnert and Donald A. Keefer
In this study, a feed-forward back-propagation neural network (BPNN) was developed and applied to predict pesticide concentrations in groundwater monitoring wells. Pesticide concentration data are challenging to analyze because they tend to be highly censored. Input data to the neural network included the categorical indices of depth to aquifer material, pesticide leaching class, aquifer sensitivity to pesticide contamination, time (month) of sample collection, well depth, depth to water from land surface, and additional travel distance in the saturated zone (i.e., distance from land surface to midpoint of well screen). The output of the neural network was the total pesticide concentration detected in the well. The model prediction results produced good agreements with observed data in terms of correlation coefficient (R = 0.87) and pesticide detection efficiency (E = 89%), as well as good match between the observed and predicted class groups. The relative importance of input parameters to pesticide occurrence in groundwater was examined in terms of R, E, mean error (ME), root mean square error (RMSE), and pesticide occurrence class groups by eliminating some key input parameters to the model. Well depth and time of sample collection were the most sensitive input parameters for predicting the pesticide contamination potential of a well. This infers that wells tapping shallow aquifers are more vulnerable to pesticide contamination than those wells tapping deeper aquifers. Pesticide occurrences during post-application months (June through October) were found to be 2.5 to 3 times higher than pesticide occurrences during other months (November through April). The BPNN was used to rank the input parameters with highest potential to contaminate groundwater, including two original and five ancillary parameters. The two original parameters are depth to aquifer material and pesticide leaching class. When these two parameters were the only input parameters for the BPNN, they were not able to predict contamination potential. However, when they were used with other parameters, the predictive performance efficiency of the BPNN in terms of R, E, ME, RMSE, and pesticide occurrence class groups increased. Ancillary data include data collected during the study such as well depth and time of sample collection. The BPNN indicated that the ancillary data had more predictive power than the original data. The BPNN results will help researchers identify parameters to improve maps of aquifer sensitivity to pesticide contamination.
Use of artificial neural networks to evaluate the effetiveness of riverbank filtration
Sahoo, Goloka, B., Chittaranjan Ray, et al.
Riverbank filtration (RBF) is a low-cost water treatment technology in which surface water contaminants are removed or degraded as the infiltrating water moves from the river/lake to the pumping wells. The removal or degradation of contaminants is a combination of physicochemical and biological processes. This paper illustrates the development and application of three types of artificial neural networks (ANNs) to estimate the effectiveness of two RBF facilities in the US. The feed-forward back-propagation network (BPN) and radial basis function network (RBFN) model prediction results produced excellent agreement with measured data at a correlation coefficient above 0.99 for filtrate water quality parameters, including temperature as well as turbidity, heterotrophic bacteria, and coliform removal. In comparison, the fuzzy inference system network (FISN) predicted only temperature and bacteria removal with reasonable accuracy. It is shown that the predictive performances of the ANNs depend on the model structure and model inputs.
Monte Carlo simulation of colloidal membrane filtration: model development with application to characterization of colloid phase transition.
Chen, Jim C., Menachem Elimelech, Albert S. Kim
This study investigates phase transition from a fluid-like polarization layer to a solid cake layer of particle deposits during membrane filtration of interacting colloidal particles. A Monte Carlo simulation model of dead-end filtration is used under the influences of hydrodynamic bias from the permeation flux as well as inter-particle interactions. The model effectively demonstrates the roles of the hydrodynamic drag force and inter-particle potential in governing the volume fraction of the particle deposit. The cake layer volume fraction is shown to be sensitive to the combination of particle surface (zeta) potential, solution ionic strength, particle size, and applied transmembrane pressure. Further application of the model leads to a holistic characterization of the phase transition phenomenon. The onset of phase transition is characterized with flexibility and adaptability with concern for both physico-chemical standards, such as volume fraction and inter-particle separation distance, as well as pragmatic considerations, such as the desire to operate the system below the critical flux and avoidance of irreversible cake formation.
Simple analytical groundwater modeling for sustainable yield estimation
Clark C.K. Liu, John F. Mink, and John Dai
Over the last twenty years, numerous modeling efforts were made to simulate the flow and salt transport processes of the Pearl Harbor aquifer, a basal freshwater lens. These modeling exercises enhanced our understanding of the aquifer. However, most of these models are too complicated, such that adequate calibration and verification require extensive field data which are not currently available. A simple robust analytical model (RAM) developed by John Mink in 1980 has been used to estimate the sustainable yield of Pearl Harbor aquifer and many other basal aquifers in the state of Hawaii. Modification of RAM is made in this study by including salt advection-dispersion processes. The modified model consists of two sub-models: (a) a flow sub-model, in the form of the original RAM, and (b) a salt transport sub-model, which simulates the evolution of the transition zone in a basal freshwater lens. The mathematical structure of the modified model remains simple such that it can be solved analytically and can be readily calibrated based on available field data of hydraulic head variations and salinity profiles. Its usefulness as a viable management tool was demonstrated by applying it hi an evaluation of the sustainable yield of the Pearl Harbor aquifer. KEY TERMS: groundwater; basal aquifer; sustainable yield.
Calibrating steady-state river water quality models with field data
Liu, Clark C.K.
In this study, a formula that separates the time-varying effect from observed dissolved oxygen (DO) data was derived. This formula calculates the steady-state DO profile along a biologically active river by “filtering” out the time-varying effect from field-measured diurnal DO curves along the river. As a result, both the model and the data used for its calibration are completely in a steady-state mode, so that model parameters which represent relevant transport and transformation processes can be determined properly.
rogoniada oahuensis, a new species from Oahu, Hawaii (Annelida: Polychaeta: Goniadidae)
Brendan M. Barrett and Julie H. Bailey-Brock
A new species of Progoniada is described. This is the third species in the genus and the first known from the Hawaiian Islands. It differs from the two previously known species in having two compound falcigerous chaetae, jaws with 5 teeth in the ventral arc, proboscis papillae of two types, and compound falcigers with blades less than half the length of the spiniger blades, Distribution in Hawaiian waters is from 34 and 70 meters at sewage outfalls and at disposal dump sites off Oahu at 397 and 502 meter depths.
Hydrodynamics of an ideal aggregate with quadratically increasing permeability
Liu, Clark C.K.
In this study, we consider the ideal aggregate with quadratically increasing permeability k = k2r2 and derive the analytical expression of the stream function within the porous aggregate by incorporating the Brinkman and continuity equations. The hydrodynamic properties of the aggregate are investigated by taking account of the hydrodynamic radius, settling velocity, and fluid collection efficiency, which are found to be solely dependent on the permeability prefactor k2. The fractal dimension Df and prefactor k2 of the ideal aggregate are found to be 5/3 (=1.67) and 0.20, respectively, and well describe the hydrodynamics of aggregates formed in the diffusion-limited-cluster-aggregation (DLCA) regime. More important, hydrodynamic similarity between the ideal aggregate and impermeable solid sphere is discovered in terms of variations of the hydrodynamic radius, settling velocity, and fluid collection efficiency with respect to the aggregate radius. Keywords: Aggregation; Fractal aggregate; Permeability; Settling velocity; Hydrodynamic radius.
The immediate effects of hurricane Iniki on interidal fauna on the south shore of Oahu
Dreyer, J., H. Bailey-Brock, and S,A, McCarthy
Validity of the generalized Richards equation for the analysis of pumping test data for a coarse-material aquifer
El-Kadi, Aly I.
This paper presents an examination of the validity of the generalized Richards equation (GRE), which includes unsaturation and compressibility effects, in the analysis of a well-documented, three dimensional aquifer test. The potential effects of wellbore storage and monitoring-well delayed response were included in the analysis. The uniqueness of the solution was also examined by testing the potential success of fully saturated models in simulating the drawdown measurements. The solution of the GRE closely matched the field measured drawdowns with some parameters that were close to their independently measured values. The aquifer-test analysis can thus provide accurate estimates for some average aquifer parameters, namely, horizontal and vertical hydraulic conductivities and specific storage. However, the model is not fully validated due to the need for calibrated soil hydraulic parameters. In general, it is possible to account for early time discrepancies by using an inflated fitting value for the specific storage. However, good accuracy was obtained using a physically based value for such a parameter when wellbore storage is considered. Sensitivity of results to values of saturated conductivity again confirmed the great importance of obtaining accurate estimates of such values. Finally, the study showed that saturated flow models did not provide results as accurate as those provided by the GRE model. Classifying the aquifer material as coarse can be misleading, considering that its effective soil properties is that of a finer texture. As such, unsaturated flow effects should not be overlooked.
Screening of polymers on selected Hawaii soils for erosion reduction and particle settling
James A. Teo, Chittaranjan Ray, and Samir A. El-Swaify
In recent years, high-molecular-weight anionic polyacrylamides (PAMs) have been tested on a variety of soils, primarily in temperate climates. However, little information is available regarding the effectiveness of PAM for preventing soil loss through runoff in tropical settings. Screening tests were performed using three negatively charged PAMs and one positively charged PAM on five Hawaii soils (two Oxisols, one Vertisol, and two Aridisols) to determine erosion loss, sediment settling, and aggregate stability. A laboratory-scale rainfall simulator was used to apply erosive rainfall at intensities from 5 to 8.5 cm h-1 at various PAM doses applied in both dry and solution forms. Soil detachment due to splash and runoff, as well as the runoff and percolate water volumes, were measured for initial and successive storms. The impact of PAM on particle settling and aggregate stability was also evaluated for selected soil-treatment combinations. Among the PAMs, Superfioc A-836 was most effective, and significantly reduced runoff and splash sediment loss for the Wahiawa Oxisol and Pakini Andisol at rates varying between 10 and 50 kg hat. Reduced runoff and splash sediment loss were also noted for PAM Aerotil-D when applied in solution form to the Wahiawa Oxisol. Significant reductions in soil loss were not noted for either the Lualualei Vertisol or the Holomua Oxisol. It is believed that the high montmorillonite content of the Lualualei Vertisol and the low cation-exchange capacity of the Holomua Oxisol diminished the effectiveness of the various PAMs tested. The polymers were also found to enhance sediment settling of all soils and helped improve their aggregate stability. This screening study shows the potential use of PAM for tropical soils for applications such as infiltration enhancement, runoff reduction, and enhanced sedimentation of detention ponds.
A new model for calculating specific resistance of aggregated colloidal cake layers in membrane filtration processes
Kim, Albert S., Rong Yuan
A simple model to evaluate hydrodynamic cake resistance due to filtered aggregates is developed in this study. An aggregate is treated as a hydrodynamically as well as geometrically equivalent solid core with a porous shell. Creeping flow past a swarm of the composite spheres is solved using Stokes’ equation and Brinkman’s extension of Darcy’s law. The dimensionless drag force () exerted on the composite sphere is analytically determined by four parameters: radius of the solid core, thickness of the porous shell, permeability of the aggregate, and occupancy fraction as defined in this paper. In certain limiting cases, converges to pre-existing analytical solutions for (i) an isolated impermeable sphere, (ii) an isolated uniformly porous sphere, (iii) an isolated composite sphere, (iv) a swarm of impermeable spheres, and (v) a swarm of uniformly porous spheres. This expression is then used to predict the specific resistance of aggregate cake formed on membrane surfaces.
Brownian dynamics, molecular dynamics, and Monte Carlo modeling of colloidal systems
Chen,Jim C., Albert S. Kim
This paper serves as an introductory review of Brownian Dynamics (BD), Molecular Dynamics (MD), and Monte Carlo (MC) modeling techniques. These three simulation methods have proven to be exceptional investigative solutions for probing discrete molecular, ionic, and colloidal motions at their basic microscopic levels. The review offers a general study of the classical theories and algorithms that are foundational to Brownian Dynamics, Molecular Dynamics, and Monte Carlo simulations. Important topics of interest include fundamental theories that govern Brownian motion, the Langevin equation, the Verlet algorithm, and the Metropolis method. Brownian Dynamics demonstrates advantages over Molecular Dynamics as pertaining to the issue of time-scale separation. Monte Carlo methods exhibit strengths in terms of ease of implementation. Hybrid techniques that combine these methods and draw from these efficacies are also presented. With their rigorous microscopic approach, Brownian Dynamics, Molecular Dynamics, and Monte Carlo methods prove to be especially viable modeling methods for problems with challenging complexities such as high-level particle concentration and multiple particle interactions. These methods hold promising potential for effective modeling of transport in colloidal systems.
Aquaculture wastewater treatment and reuse by wind-driven reverse osmosis membrane technology
Qin, Gang, Clark C.K. Liu, et al.
Nitrogen in aquaculture wastewater may cause many environmental problems to the receiving water. To protect its pristine coastal water, the State of Hawaii established stringent water quality limits for aquaculture wastewater. Effluents from aquaculture facilities in Hawaii generally exceed these limits – sometimes by one to two orders of magnitude. Development of cost-effective treatment technology would be one of the most important factors for a profitable aquaculture industry in Hawaii. Furthermore, recirculating of aquaculture wastewater is highly desirable for environmental protection and resource conservation. To achieve these goals, a wind-driven reverse osmosis (RO) technology was developed and applied for the removal of nitrogenous wastes from the culture water of tilapia on Coconut Island, the home of the Hawaii Institute of Marine Biology, University of Hawaii at Manoa. A conventional multi-blade windmill is used to convert wind energy directly to hydraulic pressure for RO membrane operation. Aquaculture wastewater passing through the RO membrane is separated into permeate (freshwater) and brine (concentrated wastewater). The permeate is recirculated to the fish tanks, while the brine is collected for possible treatment or reuse. As a result, no wastewater discharge is made to the ambient coastal water. Testing results indicated that the prototype wind-powered RO system can process and recycle freshwater at a flux of 228-366 L/h, depending on wind speed. The nitrogen removal rate ranges from 90% to 97%, and the recovery rate of the RO membrane is about 40-56%. A preliminary cost analysis shows that the production of 1.0 m3 permeate from aquaculture wastewater would cost US$ 4.00. Further study will focus on the reuse of concentrates and on further enhancement of cost-effectiveness.
Flow forecasting for a Hawaii stream using rating curves and neural networks
Sahoo, G. B. and C. Ray
This paper illustrates the applications of feedforward back propagation and radial basis function neural networks for flow prediction of a Hawaii stream and one of its tributaries that render flash flood behavior. Stream flow is estimated from stream stage, width, cross-sectional area, and mean velocity at the gaging station. Since measurement of mean velocity is time-consuming, expensive, and dangerous during high flows, alternative methods of flow forecasting are needed. Traditionally, hydrologists use rating curves for flow estimates. The United States Geological Survey has been estimating stream discharge using conventional rating curves for Hawaii streams. The rating curves are developed from records of measured stream stage and discharge. Clearly, the rating curves are set up for cases in which stream stage is the only input and discharge is the output. However, major limitations of using a rating curve are that the effects of hysteresis (i.e. loop-rating) are not taken into account, and as a result the prediction accuracy is lost when the stream changes its flow behavior. As an alternative method, artificial neural networks are proposed. The performances of artificial neural networks are examined for two input data sets: one set with and the other set without mean velocity, but both including stream stage, width, and cross-sectional area for two gaging stations on the stream. The results show that for both input data sets, well-optimized neural networks can outperform rating curves for discharge forecasting. Additionally, it is worth noting that neural networks are capable of predicting the loop-rating curve, which is impossible to predict using conventional rating curves.
Use of qualitative and quantitative information in neural networks for assessing agricultural chemical contamination of domestic wells
Arabinda Mishra, Chittaranjan Ray, and Dana W. Kolpin
A neural network analysis of agrichemical occurrence in groundwater was conducted using data from a pilot study of 192 small-diameter drilled and driven wells and 115 dug and bored wells in Illinois, a regional reconnaissance network of 303 wells across 12 Midwestern states, and a study of 687 domestic wells across Iowa. Potential factors contributing to well contamination (e.g., depth to aquifer material, well depth, and distance to cropland) were investigated. These contributing factors were available in either numeric (actual or categorical) or descriptive (yes or no) format. A method was devised to use the numeric and descriptive values simultaneously. Training of the network was conducted using a standard backpropagation algorithm. Approximately 15% of the data was used for testing. Analysis indicated mat training error was quite low for most data. Testing results indicated that it was possible to predict the contamination potential of a well with pesticides. However, predicting the actual level of contamination was more difficult. For pesticide occurrence in drilled and driven wells, the network predictions were good. The performance of the network was poorer for predicting nitrate occurrence in dug and bored wells. Although the data set for Iowa was large, the prediction ability of the trained network was poor, due to descriptive or categorical input parameters, compared with smaller data sets such as that for Illinois, which contained more numeric information.
Usefulness of monitoring tropical streams for male-specific RNA coliphages
Luther, Kartini, and Roger Fujioka
The objective of this study was to evaluate the usefulness of monitoring streams in Hawaii for FRNA coliphages as a reliable indicator of sewage contamination. This study was undertaken as a result of our previous findings that monitoring streams in Hawaii for traditional faecal indicator bacteria (faecal coliform, Escherichia coll, enterococci) was not useful in determining when streams are contaminated with sewage, because environmental (soil) sources rather than sewage accounted for the high concentrations of faecal bacteria in streams. Two perennial streams, sewage and soil samples were monitored for traditional faecal indicator bacteria (faecal coliform, coll, enterococci) and FRNA coliphages. The results showed that sewage treatment processes and disinfection drastically reduced the concentrations of traditional faecal indicator bacteria but FRNA coliphages were still present in significant concentrations in the treated sewage effluents. These results indicate that monitoring sewage effluents and environmental waters for only traditional faecal indicator bacteria may not be adequately protective of human health effects. Ambient concentrations of traditional faecal indicator bacteria in soil and streams of Hawaii were consistently high but consistently low for FRNA coliphages, indicating that monitoring streams of Hawaii for FRNA coliphages can be used to determine when streams are contaminated with sewage.
Modeling RBF Efficacy for mitigating chemical shock loads
Riverbank filtration (RBF) offers several advantages over the direct use of surface water. A number of dissolved and suspended contaminants of surface waterincluding pathogens and microscopic particlesare removed during passage of surface water through the river sedimentaquifer system. Many dissolved chemicals undergo biogeochemical reactions and dilution, leading to reductions in concentrations of parent species. This research examined the potential of RBF systems to attenuate chemical shock loads that may result from chemical spills or spring flooding in agricultural watersheds. Scenarios simulated both horizontal and vertical wells, with riverbed and bank hydraulic properties varying as a function of river stage. The solute transport equation considered a range of reaction parameters. Sensitivity analysis showed that the hydraulic conductivity of the riverbed or bank materials had a pronounced effect on filtrate quality. For materials with low hydraulic conductivity, the effect on filtrate quality would be minimal, and the lag time between the contaminant peak concentrations in the surface water and the pumped water would be significant. However, further biogeochemical modeling is needed to predict the fate of contaminants during their transit to the pumping wells. Use of backup vertical wells of selected laterals of a collector well could effectively mitigate the risks.
Integrating entrapped mixed microbial cell (EMMC) process for biological removal of carbon and nitrogen from dilute swine wastewater
Yang, P.Y., H.J. Chen, S.J. Kim
An entrapped mixed microbial cell (EMMC) process was used to investigate the simultaneous removal of carbon and nitrogen from dilute swine wastewater. Cellulose triacetate was used as the matrix for entrapping the mixed microbial cells. The EMMC process was tested under various oxygen supply conditions (ratios of aeration to non-aeration times) and two types of carrier sizes (large and medium). Also, various pre-treatments with chemical coagulation, screen separation, and ammonium crystallization prior to the EMMC process and post-treatment following the EMMC process were investigated. It was found that at a hydraulic retention time of 30 hours and 1 hour of aeration and 1 hour of non-aeration, the EMMC process packed with medium carriers after the pre-treatment of ammonium crystallization exhibited the best total nitrogen removal efficiency of 95.1 1.0% when compared to two other pre-treatment methods. The total chemical oxygen demand (TCOD) and soluble chemical oxygen demand removal efficiencies were 83.5 2.2% and 84.1 1.1%, respectively. Lime post-treatment provided TCOD and total phosphorus removal efficiencies of 59.6 2.7% and 98.0 0.5%, respectively. Thus, a cost analysis for ammonium crystallization pre-treatment, EMMC process, and post-treatment with lime was conducted. The unit cost for a 2,000-pig operation is $4.91/pig/year. For the application of the EMMC process with the proposed pre- and post-treatments, a suitable farm size needs to be greater than a 2,000-pig operation. Because of the high efficiency and the simple operation of simultaneous carbon and nitrogen removal, the EMMC process has the potential for treatment of dilute swine wastewater in a land-limited area and can be manufactured as pre-fabricated wastewater treatment units.
Modeling depth-variant and domain-specific sorption and biodegradation in dual-permeability media
Ray, Chittaranjan, Tomas Vogel and Jaromir Dusek
A dual-permeability model (S_1D_DUAL) was developed to simulate the transport of land-applied pesticides in macroporous media. In this model, one flow domain was represented by the bulk matrix and the other by the preferential flow domain (PFD) where water and chemicals move at faster rates. The model assumed the validity of Darcian flow and the advective-dispersive solute transport in each of the two domains with inter-domain transfer of water and solutes due to pressure and concentration gradients. It was conceptualized that sorption and biodegradation rates vary with soil depth as well as in each of the two flow domains. In addition to equilibrium sorption, kinetic sorption was simulated in the PFD. Simulations were conducted to evaluate the combined effects of preferential flow, depth- and domain-variant sorption, and degradation on leaching of two pesticides: one with strong sorption potential (trifluralin) and the other with weak sorption potential (atrazine). Simulation results for a test case showed that water flux in the PFD was three times more than in the matrix for selected storm events. When equilibrium sorption was considered, the simulated profile of trifluralin in each domain was similar; however, the atrazine profile was deeper in the PFD than in the bulk matrix under episodic storm events. With an assumption of negligible sorption in the PFD, both the atrazine and the trifluralin profiles moved twice deeper into the PFD. The simulated concentrations of the chemicals were several orders higher in the PFD than in the matrix, even at deeper depths. The volume fraction of the macropores and the sorption and biodegradation properties of the chemicals could also affect the amount of pesticides leaving the root zone. For an intense storm event, slow sorption reaction rates in the PFD produced higher breakthrough concentrations of atrazine at the bottom of the simulated soil profile, thus posing the risk for breakthrough of chemicals from the root zone.
Three new species of Saccocirrus (Polychaeta: Saccorcirridae) from Hawaii.
Bailey – Brock, Julie H., J. Dreyer, and R.E. Brock
Three new species of saccocirrids from interstitial sand habitats off O’ahu, Hawai’i, are described. Two are from subtidal depths, 9-33 m, and the third is from the intertidal to 3.5 m deep on a fringing reef and at Hanauma Bay, the Marine Life Conservation District and public park. The two deeper-water species, Saccocirrus oahuensis, n. sp. and 5. waianaensis, n. sp., have 76-119 and 157-210 segments, respectively; they also have bilateral gonads but lack a pharyngeal pad. The third, S. alanhongi, n. sp., has 35-47 segments, unilateral gonads, and a muscular pharyngeal pad. These species are distinguished from 18 known Saccocirrus spp. by their unique chaetation, number of segments, presence or absence of ventral cilia, and pygidial adhesive structures. Saccocirrus oahuensis consumes foraminiferans, and S. alanhongi contained diatoms, unicellular algae, and ostracods. These species add to the interstitial fauna of O’ahu and cooccur with polychaetes Nerilla antennata (Nerillidae) and protodrilids (Protodrilidae), and Kinorhyncha. Saccocirrus alanhongi withstands almost daily disturbance by 600-1200 bathers per day entering the sandy swimming holes in the reef at Hanauma Bay.
Protozoal and epitheliocystis-like infections in the introduced bluestripe snapper Lutjanus kasmira in Hawaii
Work, Thierry M., Robert A. Rameyer, Geraldine Takata, Michael L. Kent
The bluestripe snapper, or taape, was introduced into Hawaii in the 1950s and has since become very abundant throughout the archipelago. As part of a health survey of reef fish in Hawaii, we necropsied 120 taape collected from various coastal areas south of Oahu and examined fish histology for extraintestinal organisms. Forty-seven percent of taape were infected with an apicom-plexan protozoan compatible with a coccidian. Infection was evident mainly in the spleen and, less commonly, the kidney. Prevalence of this coccidian increased with size of fish, and we saw no significant pathology associated with the organism. Twenty-six percent of taape were also infected with an epitheliocystis-like organism that occurred mainly in the kidney and, less commonly, the spleen. In contrast to the coccidian, fish mounted a notable inflammatory response to the epitheliocystis-like organism, and this inflammation appeared to increase in severity with age. Prevalence of the epitheliocystis-like organism infection increased with age, but infection was not seen in fish greater than 26.5 cm fork length. The high prevalence of coccidial infection in introduced taape prompts the concern that these organisms, along with the epitheliocystis-like organism, have the potential to be transmitted to native reef fish. Given the impact of other introduced microbial organisms on native Hawaiian fauna, there is a clear need to assess whether protozoa and bacteria are endemic to Hawaii, and whether they negatively impact native reef fish that closely associate with taape.
KEY WORDS: Bluestripe snapper o Lutjanus kasmira o Apicomplexa o Protozoa o Epitheliocystis-like organism o Pathology o Epizootiology
Rainwater roof catchment systems, microbial quality of
Fujioka, Roger S.
Clean and safe water piped to homes by a reliable supplier (water utility) and available at the turn of a tap is taken for granted by most people in developed countries. However, in developing countries, large populations of people are not supplied with clean water piped into their homes. Even in developed countries, many houses do not receive piped water from a public water utility because of practical or economical conditions related to houses being too far away from a public water utility, houses being located at too high an elevation, or because the houses in rural areas are too few and too scattered. Under these conditions, homeowners will rely on the most feasible source of water for their household needs, such as surface waters (rivers, streams, lakes) or groundwater sources (boreholes, wells). However, under some conditions these sources of water are not readily available, and harvesting (collecting and storing) rainwater may be the most feasible way to obtain water for household use. In its simplest form, open tanks can serve the dual purpose of collecting and storing rainwater. However, this method is applicable only to few places where rainfall is frequent and the volume of water required is low. In most situations, a designated surface area or catchment is required to collect sufficient volumes of rainwater. The objective of this review is to assess the microbial and hygienic quality of rainwater collected from roof catchment systems from private homes and stored in cisterns or tanks for household use.
Monitoring Honolulu’s groundwater sources for human enteric viruses using cell culture and cell-culture PCR
Fujioka, Roger, Audrey Asahina, Geeta Rijal, and J. Alfredo Bonilla
The Honolulu Board of Water Supply (HBWS) is the largest water utility in the state of Hawaii and chlorinates only 50% of its deep (600 feet) groundwater sources to provide 150 mgd of potable water. The water quality in the distribution system contains low to undetectable levels of chlorine but meets the Total Coliform Rule. However, the upcoming Groundwater Rule (GWR) recommends that groundwater sources be chlorinated to reach a 0.2 mg/l residual in the distribution system as a treatment process to disinfect contaminating pathogens. Guidance under the GWR indicate that water utilities may be granted a variance to this disinfection requirement if their groundwater sources are naturally protected and are not vulnerable to contamination with fecal matter. In a previous study, the groundwater sources used by HBWS were monitored for multiple fecal indicator microorganisms (total coliforms, fecal coliforms, E. coli, fecal streptococci, C. perfringens, FRNA coliphages). Since most of 79 groundwater samples did not contain these fecal indicator microorganisms, it was concluded that these groundwater sources are naturally protected from fecal matter. However, human enteric viruses are the most likely pathogen to contaminate groundwater and are known to survive longer and are transported more readily through the soil environment than fecal bacteria. The objective of this study was to analyze HBWS groundwater sources for human enteric viruses. The experimental design of this study was to process 200 gallons of groundwater and to analyze these samples for infectious human enteric viruses using the standard cell culture method as well as the integrated cell culture and polymerase chain reaction (ICC-PCR) method. A total of 45 groundwater sources were initially determined to be negative for human enteric viruses by cell culture method and by the standard ICC-PCR results. However, based on seeding poliovirus into mock samples, the standard ICC-PCR method was determined to be unreliable due to interferences from sample components. A modified ICC-PCR was developed to increase the sensitivity of the assay method. Using this modified method, 40 of the groundwater samples tested were shown to be negative for human enteric viruses. Two conclusions can be drawn from this study. First, that PCR methods must be optimized for each laboratory before they a re used. Second, the absence of human enteric viruses in all groundwater samples by cell culture and PCR method indicate that the groundwater sources used by the HBWS are not vulnerable to contamination by human enteric viruses.
ale-specific RNA coliphages are reliable markers of sewage (point source) contamination
Luther, K. and R. Fujioka
Concentrations of U.S. Environmental Protection Agency-approved fecal indicator bacteria (fecal coliform, E. coli, enterococci) in environmental waters are used to determine the extent of sewage contamination and to establish recreational water quality standards. These water quality standards are used to determine the risk or probability that someone using that body of water for primary contact recreational use (e.g., swimming) will become ill from sewage-borne pathogens. The current EPA-recommended marine recreational water quality standards were developed from results of previously completed epidemiological and water quality studies at three beach sites (New York City, Boston Harbor, and Lake Pontchartrain) in the United States. These sites were selected because concentrations of fecal bacteria were barely acceptable due to nearby sewage discharges. Similar studies were conducted for fresh recreational waters at lakes in Pennsylvania and Oklahoma. Results of these studies (Cabelli et al., 1982; USEPA, 1986) have led to different recreational water quality standards for marine waters and for fresh waters. For marine waters, the EPA-recommended recreational water quality standard is a geometric mean concentration of 35 enterococci/100 ml based on five weekly samples taken over a month. For fresh waters, the EPA-recommended standards are similar geometric mean concentrations of 33 enterococci/100 ml or 126 E. coli/100 ml. The results of these EPA studies showed that concentrations of enterococci in marine and fresh waters correlated with incidences of swimming-associated gastroenteritis whereas concentrations of E. coli correlated with swimming-associated gastroenteritis only in fresh waters. A significant conclusion of the EPA studies was the finding that concentrations of fecal coliforms in marine and fresh waters did not correlate with swimming-associated gastroenteritis. EPA concluded that the most likely sewage-borne pathogens causing gastroenteritis was Norwalk type viruses (Cabelli et al., 1982). It was concluded that E. coli was too unstable in marine waters to serve as a reliable surrogate for the presence of sewage-borne pathogens. It should be noted that EPA conducted a similar epidemiological study at a lake in Connecticut. This lake was not contaminated with sewage, and fecal indicator bacteria in the lake were from non-point sources such as wild animals rather than from a point source (sewage). Under these conditions, the concentrations of enterococci and E. coli did not correlate with swimming-associated gastroenteritis (Calderon et al., 1991).
Experiments of a prototype wind-driven reverse osmosis desalination system with feedback control
Liu, Clark C.K., Jae-Woo Park, Reef Migita, and Gang Qin
A prototype wind-powered reverse osmosis desalination system was constructed and tested on Coconut Island off the northern coast of Oahu, Hawaii, for brackish water desalination. The system has four major subsystems: a multi-vaned windmill/pump, a flow/pressure stabilizer, a reverse osmosis module, and a control mechanism. The feedback control mechanism, developed by this study, allowed this prototype system to be operated satisfactorily under mild ambient wind of 5 m/s or less. No auxiliary power source was needed. The system operational data showed that at an average wind speed of 5 m/s, brackish feedwater at a total dissolved solids concentration of 3000 mg/l and at a flow rate of 13 l/min could be processed by this system. The average rejection rate of this prototype system was 97% and the average recovery ratio as 20%. The energy efficiency of the system was measured at 35%, which is comparable to the typical energy efficiency of well-operated multi-vaned windmills. Generally, the system’s energy efficiency decreases as wind speed increases.
Artificial upwelling and near-field mixing of deep-ocean water effluent
Liu, Clark C.K, In Mei Sou, and Huashan Lin
Deep-ocean water (DOW) as a depth of 300 m or lower is cold, nutrient-rich, and free of pathogenic bacteria. This water is considered an important natural resource. One of the fully developed technologies of DOW application is ocean thermal energy conversion (OTEC), which makes use of DOW for energy production. In recent years, the potential of DOW to enrich the open oceans and thus to increase fish yield has attracted the attention of researchers. Before this potential can be realized, however, major scientific and technological developments concerning artificial upwelling, plume mixing, and DOW simulated bio-productivity must be achieved. This study, which is a continuation of earlier research on artificial upwelling at the University of Hawaii, investigates the effects of discharging artificially upwelled DOW into the open ocean where it is subsequently mixed with surface water. The study involves both hydraulic modeling and numerical simulation, and its objective is to control the near-field mixing of DOW effluent such that the dilution is small and the settling depth does not go below the euphotic zone. Special attention is given to wave effects on the near-field mixing processes. Research results indicate that, with proper effluent control, desirable nutrient-rich DOW plumes can be established and maintained in the open ocean.
Polychaetes associated with a tropical ocean outfall: Synthesis of a biomonitoring program off Oahu, Hawaii
Bailey-Brock, J.H., B. Paavo, B.M. Barrett, and J. Dreyer
A comparison of benthic polychaete communities off the Sand Island Wastewater Outfall was undertaken to recognize organic enrichment indicator species for Hawaiian waters. Primary-treatment sewage is discharged off the south shore of O’ahu at 70 m depth. A historical data set spanning 9 yr for seven sites at 70 m and two recent studies at 20, 50, and 100 m depths were analyzed. Geochemical data did not support the assumption that the outfall is an important source of organic enrichment in nutrient-poor sandy sediments within oligotrophic tropical waters. Five polychaete species, however, appeared particularly sensitive, positively or negatively, to environmental conditions near the outfall. Neanthes arenaceodentata (Nereididae) and Ophryotrocha adherens (Dorvilleidae) have been dominant at sites within the outfall’s zone of initial dilution (ZID). Since 1993, N. arenaceodentata has virtually disappeared, and O. adherens concurrently became abundant and continued to flourish at ZID sites. Well-known indicators within the Capitella capitata complex (Capitellidae) were present at ZID and control (far field) sites though their ZID abundance was greater. Two sabellids, Euchone sp. B and Augeneriella dubia were inversely distributed, the smaller Euchone sp. B at far field sites and larger A. dubia within ZID stations. The former was most likely restricted to a greater proportion of fine sediment particles at two far field sites. The most abundant and widespread polychaete off O’ahu’s south shore was Pionosyllis heterocirrata (Syllidae), which does not seem to represent a sensitive indicator species. Ophryotrocha adherens was the most abundant indicator species within the ZID; P. heterocirrata was the most ubiquitous species at all sites and should always be expected in these sediments. Traditional measurements of numerical abundance, species richness, and diversity (H’) have not shown a clear distinction between ZID and far field sites in annual analyses. An examination of composited data over an 11-yr period does support such a distinction. Multidimensional scaling (MDS) analyses clearly delineate different assemblages. We suggest that MDS analyses are sensitive to the community differences present near the outfall. The ZID community is clearly contained within the Environmental Protection Agency-approved ZID boundary. Because each ZID and far field site supports a diverse and coarsely similar polychaete fauna, no pollution level effects seem to be present.
Use of reflectors to enhance the synergistic effects of solar heating and solar wavelengths to disinfect drinking water sources
Rijal, G.K. and R.S. Fujioka
Aluminum reflectors were added to solar units designed to inactivate faecal microorganisms (faecal coliform, E. coli, enterococci, FRNA coliphage, C. perfringens) in stream water and diluted sewage by the two mechanisms (solar heat, solar UV) known to inactivate microorganisms. During sunny condition, solar units with and without reflectors inactivated E. coli to <1 CFU/100 ml to meet drinking water standards. Solar units with reflectors disinfected the water sooner by increasing the water temperature by 8–10oC to 64–75oC. However, FRNA coliphages were still detected in these samples, indicating that this treatment may not inactivate pathogenic human enteric viruses. During cloudy condition, reflectors only increased the water temperature by 3–4oC to a maximum of 43–49oC and E. coli was not completely inactivated. Under sunny and cloudy conditions the UV wavelengths of sunlight worked synergistically with increasing water temperatures and were able to disinfect microorganisms at temperatures (45–56oC), which were not effective in inactivating microorganisms. Relative resistance to the solar disinfecting effects were C. perfringens > FRNA coliphages > enterococci > E. coli> faecal coliform.
Microbial indicators of marine recreational water quality
Fujioka, Roger S.
The value of coastal waters is clearly evident from the observation that nearly two-thirds of the world’s population make their homes within 150 km of the shore (31). The obvious advantages of living near coastal areas are a moderate climate, ease of transportation, sources of food, and jobs. However, when people live near coastal water, they also develop social and cultural values associated with coastal waters (20). More recently, people have recognized the esthetic and recreational values of coastal waters. As a result, people today travel long distances to spend their valuable vacation time at coastal water sites which are especially suitable for swimming, sunbathing, surfing, and fishing. To meet all of these values of coastal waters, there has been a dramatic increase in the building of cities, industries, homes, hotels, restaurants, shops, parks, harbors, and many tourist-related facilities in coastal areas. Unfortunately, these activities, along with the commensurate increase in population, inevitably result in increased production of point source pollution such as sewage and industrial discharges as well as nonpoint source pollution such as agricultural and urban runoff, especially storm drains. In coastal areas, these kinds of pollution generally discharge into and pollute coastal waters (40). Recognizing this problem, effective environmental regulations have been implemented to properly treat and dispose of point source discharges. However, nonpoint source discharges have generally not been regulated, and therefore these kinds of discharges are not treated and pollute shoreline coastal waters, often in close proximity to waters designated for swimming. In this regard, a recent report by the U.S. Environmental Protection Agency (EPA) estimates that the water quality at 40% of the nation’s recreational waters is unsuitable for swimming and that contamination is due primarily to nonpoint source pollution (Beach Watch website: http://www.epa.gov/ost/beaches). Today, many of our popular beaches are susceptible to pollution, and the suitability of these waters for swimming is often questioned. Diseases acquired from recreational use of waters are of great concern to city officials, public health agencies, and the tourism industry. To address this concern, expensive programs have been implemented to control coastal water pollution, to establish water quality standards, and to constantly monitor these waters to ensure that recreational waters designated for swimming are suitable for swimming.
Linear systems approach to river water quality analysis
Liu, Clark C.K. and Jenny Jing Neill
The water quality of a polluted river can be improved either by increasing the river’s self-purification ability or by reducing the amount of waste loading the river receives. Traditional physically based water quality models do not evaluate separately a receiving river’s purification ability and the effect of waste loading; thus, these models are not ideal analytical tools for water quality management. This chapter introduces and discusses an alternative river water quality modeling approach based on the linear systems theory. In a linear systems model, a receiving river’s self-purification ability is represented completely by the model’s, impulse response function, whereas the amount of waste loading the river receives is represented by the model’s input function. These two functions can be evaluated separately. Further, a simple convolution integration of these two functions gives the system output. Usually, the system output is the water quality condition of the receiving river. The linear systems model’s usefulness as a water quality management tool is demonstrated in this chapter by applying it to studies of dissolved oxygen variations (1) in a steady-state river system that receives both point-source and nonpoint-source waste loading and (2) in a time-variable river system that receives point-source waste loading in the form of periodic function.
Monitoring coastal marine waters for spore-forming bacteria of faecal and soil origin to determine point from non-point source pollution
The US Environmental Protection Agency (USEPA) and the World Health Organization (WHO) have established recreational water quality standards limiting the concentrations of faecal indicator bacteria (faecal coliform, E. coli, enterococci) to ensure that these waters are safe for swimming. In the application of these hygienic water quality standards, it is assumed that there are no significant environmental sources of these faecal indicator bacteria which are unrelated to direct faecal contamination. However, we previously reported that these faecal indicator bacteria are able to grow in the soil environment of humid tropical island environments such as Hawaii and Guam and are transported at high concentrations into streams and storm drains by rain. Thus, streams and storm drains in Hawaii contain consistently high concentrations of faecal indicator bacteria which routinely exceed the EPA and WHO recreational water quality standards. Since, streams and storm drains eventually flow out to coastal marine waters, we hypothesize that all the coastal beaches which receive run-off from streams and storm drains will contain elevated concentrations of faecal indicator bacteria. To test this hypothesis, we monitored the coastal waters at four beaches known to receive water from stream or storm drains for salinity, turbidity, and used the two faecal indicator bacteria (E. coli, enterococci) to establish recreational water quality standards. To determine if these coastal waters are contaminated with non-point source pollution (streams) or with point source pollution (sewage effluent), these same water samples were also assayed for spore-forming bacteria of faecal origin (C. perfringens) and of soil origin (Bacillus species). Using this monitoring strategy it was possible to determine when coastal marine waters were contaminated with non-point source pollution and when coastal waters were contaminated with point source pollution. The results of this study are most likely applicable to all countries in the warm and humid region of the world.
Synergistic effect of solar radiation and solar heating to disinfect drinking water sources
Rijal, G.K. and R.S. Fujioka
Waterborne diseases are still common in developing countries as drinking water sources are contaminated and feasible means to reliably treat and disinfect these waters are not available. Many of these developing countries are in the tropical regions of the world where sunlight is plentiful. The objective of this study was to evaluate the effectiveness of combining solar radiation and solar heating to disinfect contaminated water using a modified Family Sol-Saver System (FSP). The non-UV transmittable cover sheet of the former FSP system was replaced with an UV transmittable plastic cover sheet to enable more wavelengths of sunlight to treat the water. Disinfection efficiency of both systems was evaluated based on reduction of the natural populations of faecal coliform, E. coli, enterococci, C. perfringens, total heterotrophic bacteria, hydrogen sulphide producing bacteria and FRNA virus. The results showed that under sunny and partly sunny conditions, water was heated to critical temperature (60°C) in both the FSP systems inactivating more than 3 log (99.9%) of the concentrations of faecal coliform and E. coli to undetectable levels of <1 CFU/100 mL within 2–5 h exposure to sunlight. However, under cloudy conditions, the two FSP systems did not reduce the concentrations of faecal indicator bacteria to levels of <1 CFU/100 mL. Nonetheless, sufficient evidence was obtained to show that UV radiation of sunlight plus heat worked synergistically to enhance the inactivation of faecal indicator bacteria. The relative log removal of indicator microorganism in the FSP treated water was total heterotrophic bacteria < C. perfringens < FRNA virus < E. coli< faecal coliform. In summary, time of exposure to heat and radiation effects of sunlight were important in disinfecting water by solar units. The data indicated that direct radiation of sunlight worked synergistically with soar heating of the water to disinfect the water. Thus, effective disinfection was observed even when the water temperature did not reach 60°C. Finally, the hydrogen sulphide test is a simple and reliable test that householders can use to determine whether their water had been sufficiently disinfected.
Liu, Clark C.K.
Recent events and research on wastewater reuse are covered.
Video transects and their use in the environmental assessment of deep water marine disposal sites
Miller, Jacquelin N., Roy H. Wilkens, and Peter Wathern
Environmental studies of proposed or designated disposal sites are directed by regulations that presently require extensive sampling of all possible components of biological, chemical, and physical characteristics of the sites with little regard for the application of this data to predicting real, as contrasted to perceived, impacts to the environment. These broad-brush studies are poorly focused, may provide little guidance for measuring actual impacts, and are extremely costly. To address these problems, a new method of carrying out environmental assessments of deep water dredged material disposal sites has been developed that incorporates the latest developments in both video imaging and computer analysis as well as selective, habitat based, sampling.
Microbial ecology controls the establishment of fecal bacteria in tropical soil environment
Fujioka, R.S. and M.N. Byappanahalli
Fecal indicator bacteria such as E. coli and enterococci are consistently present in Hawaii’s streams in concentrations exceeding recreational water quality standards. The source of these fecal indicator bacteria has been determined to be the soil where these bacteria are able to multiply and have become part of the soil microflora. The mechanisms by which these fecal bacteria are able to multiply under ambient soil conditions have not been determined. The objective of this study was to test two hypotheses by which these fecal bacteria can establish populations in the soil environment. The first hypothesis states that the soil environment is restrictive for the growth of fecal bacteria but a sub-population of fecal bacteria with metabolic characteristics adaptable to growth in soil will be selected to establish a population. The second hypothesis states that the soil environment is permissive and most strains of fecal bacteria will be able to multiply and become part of the soil microflora. The metabolic profile of soil isolates of 48 E. coli and 30 enterococci were determined based on their ability to metabolize 95 different carbon sources using the Biolog System. These results showed that many metabolically diverse strains of E. coli as well as six different species of Enterococcus were recovered from seven different groups of soil in Hawaii. These results support the hypothesis that soil conditions in Hawaii are permissive for the growth of most strains of fecal bacteria. Thus, the genetic capabilities of fecal bacteria are sufficiently robust to overcome all of the ecological constraints in the soil environment and have succeeded in becoming a minor but significant fraction of the soil microflora.
Assessing the vulnerability of groundwater sources to fecal contamination
Fujioka, Roger S. and Bunnie S. Yoneyama
The Honolulu Board of Water Supply (HBWS) selectively chlorinates half of its groundwater supply to provide drinking water that meets the Total Coliform Rule. The objective of this study was to determine whether the groundwater sources used by HBWS are vulnerable to contamination with fecal matter and would require routine disinfection. Larger volumes (1,000 ml) of samples from groundwater and from the distribution system were more sensitive than standard volumes (100 ml) in the detection for total coliform, fecal coliform, Escherichia coli, and fecal streptococcus. Confirmed fecal indicator bacteria were detected in 2 of 79 groundwater samples and from none of the 152 distribution system water samples, indicating that the groundwater has a low incidence of contamination and the selective chlorination program effectively reduces this level of contamination. Analysis of 1,000-ml samples of groundwater is recommended but is not included in the recent guidelines of the proposed Ground Water Rule.
One last visit to the capillarity correction for free surface flow
Fink, James P., J.-Y. Parlange, and Aly I. El-Kadi
When a capillarity correction is incorporated into the diffusion equation to describe the sudden drawdown of a water table, the resulting differential equation preserves, instead of smoothes, irregularities in the initial data. We describe how this problem can be handled by a proper and careful interpretation of the initial conditions, explain why it works, and illustrate the resulting behavior with numerical experiments.
Identifying variably saturated water-flow patterns in a steep hillslope under intermittent heavy rainfall
El-Kadi, Aly I. and Jill D. Torikai
The objective of this paper is to identify water-flow patterns in part of an active landslide, through the use of numerical simulations and data obtained during a field study. The approaches adopted include measuring rainfall events and pore-pressure responses in both saturated and unsaturated soils at the site. To account for soil variability, the Richards equation is solved within deterministic and stochastic frameworks. The deterministic simulations considered average water-retention data, adjusted retention data to account for stones or cobbles, retention functions for a heterogeneous pore structure, and continuous retention functions for preferential flow. The stochastic simulations applied the Monte Carlo approach which considers statistical distribution and autocorrelation of the saturated conductivity and its cross correlation with the retention function. Although none of the models is capable of accurately predicting field measurements, appreciable improvement in accuracy was attained using stochastic, preferential flow, and heterogeneous pore-structure models. For the current study, continuum-flow models provide reasonable accuracy for practical purposes, although they are expected to be less accurate than multi-domain preferential flow models.
System development and testing of wind-powered reverse osmosis desalination for remote Pacific islands
Liu, C.C.K., R. Migita, and J.-W. Park
Reverse osmosis (RO) is one of the most feasible methods of desalination to produce a supplemental freshwater supply. Because traditional RO desalination is energy-intensive, it is not a viable solution for remote Pacific islands where electricity is also in short supply. The utilization of wind power holds promise as a solution to this problem, as most of these remote islands are subject to constant trade winds. RO desalination of brackish groundwater, which is available in many of these islands, requires low feed water pressure that can be delivered by wind power at a moderate wind speed. Testing of a prototype wind-powered RO desalination system constructed on Coconut Island, a small island off the windward coast of Oahu, Hawaii, indicated that at an average wind speed of 8.5 m/s, a freshwater flow of over 4000 L/d can be produced. This volume is sufficient to meet the freshwater needs of a typical remote island community. Keywords Brackish water; reverse osmosis; system control; wind power
Changes in pollution indicators at the Sand Island sewage outfall
Bailey-Brock, Julie H., Brian Paavo, Brendan M. Barrett, and Jennifer Dreyer
Comparison of benthic communities off the Sand Island Ocean Outfall was undertaken to recognize pollution indicator species for Hawaiian waters. The primary treatment sewage is discharged off the south shore of O’ahu at 70m depth. A historical data set spanning 15 years for seven sites at 70m (4 ZED and 3 far field) and two recent studies at 20, 50, and 100m were compared. Polychaetes collected with a 7.6 cm diameter sediment core were sorted and five indicator species tentatively identified. Neanthes arenaceodentata (F. Nereididae) and Ophryotrocha adherens (F. Dorvilleidae) have been dominant at ZID stations. Since 1993, N. arenaceodentata has virtually disappeared from the ZID while O. adherens became abundant and continues to flourish there. The well known indicators within the Capitella capitata complex (F. Capitellidae) are present at ZID and far field sites. Two sabettids, Euchone sp. B and Augeneriella dubia are inversely distributed, the smaller Euchone sp. B at the far field stations and larger A. dubia at the ZID. The former is most likely restricted to the greater proportion of fine sediment particles at two far field sites. Pionosyllis heterocirrata (F. Syllidae) is the most abundant and widespread polychaete off O’ahu’s south shore. These indicator species share life history and feeding traits that lead to rapid growth and onset of reproduction, and produce benthic juveniles that recruit to the parent population leading to high levels of abundance. The success of indicator species is due to rapid use of available food resources and resulting increase in abundance. O. adherens is the most abundant indicator species at the ZID, P. heterocirrata is the most ubiquitous species at all sites and should always be present in these sediments. No pollution level effects on the benthic assemblages seem to be present, but fluctuations in indicator abundances may indicate a response to organic materials such as sewage outfalls. Future changes in benthic assemblages on O’ahu’s south shore need to consider all possible organic sources including sewage effluent, fish farm wastes, land run off, canal and harbor drainage and the effects of beach nourishment projects.
Development and assessment of a fecal bacterial monitoring program to determine the impact of ocean sewage outfall on shoreline water quality
Fujioka, R., C. Fujioka, and R. Oshiro
An innovative monitoring study, based on analyzing water samples at sampling stations near the Sand Island Ocean Outfall for three fecal indicator bacteria (E. coli, enterococci, and C. perfringens), was completed. Monitoring for these bacteria was useful because each is present in wastewater at different concentrations and survives in ocean water environments at different rates. The wastewater being discharged into the ocean via the ocean outfall pipe was documented to contain high concentrations of the three fecal bacteria. The monitoring data were used to assess the movement of fecal bacteria from the ocean outfall to shoreline stations where most people use the water for recreational purposes. Data were obtained to show that the wastewater from the ocean outfall did not surface but remained submerged to be transported away by ocean currents and be further diluted by ocean water. Since the concentrations of fecal bacteria at the Nearshore Stations and at the Shoreline Stations met the current recreational water quality standards, it was concluded that the wastewater discharged from the Sand Island Ocean Outfall was not being transported to the Shoreline Stations to measurably impact on the microbial quality of water there. Nonpoint sources of fecal bacteria can affect shoreline water quality. Instances of elevated fecal bacterial counts at the Nearshore Stations were observed, indicating that the wastewater from the ocean outfall was occasionally being transported to the Nearshore Stations. The difficulty of interpreting a single day of elevated counts and the many complications involved in interpreting monitoring data near ocean sewage outfalls were reviewed.
Macrobenthos monitoring near the Sand Island and Barbers Point Ocean Outfalls, Oahu, Hawaii
Swartz, R.C., J.H. Bailey-Brock, W.J. Cooke, and E.A. Kay
The Sand Island and Barbers Point primary treatment plants discharge wastewaters into Mamala Bay through ocean outfalls located off the southern coast of O’ahu, Hawai’i at a water depth of approximately 60 m. The macrobenthos in the vicinity of these outfalls has been monitored since 1986. Replicate grabs at multiple stations located along transects and depth contours have been collected to provide biological samples for quantitative analyses. Samples for analysis of sediment grain size and parameters of sediment organic enrichment have also been collected. Benthic conditions at sites near the outfalls have been compared with reference conditions at sites 3 to 6 km from the outfalls to assess biological changes that might be related to the wastewater discharges. The structure of mollusk, nonmollusk (all macrobenthos excluding mollusks), and crustacean assemblages has been analyzed separately. Parameters of biological conditions include number of individuals, number of species, diversity (H1), evenness (J), faunal similarity (Bray-Curtis index), indicator species, and dominant species composition. Conditions have been compared in space (among stations from a single survey) and in time (among samples from different surveys; usually conducted near each outfall on an annual basis). Sediments, which were composed primarily of fine to coarse sands, showed no evidence of organic enrichment at any station. A diverse and abundant macrobenthos has been sampled near the two outfalls. Samples from each survey typically contained hundreds of benthic taxa and more than 10,000 individuals. Analyses of the abundance, taxa richness, and diversity of mollusks and nonmollusks almost always showed no statistically significant reductions at sites near the outfalls relative to reference sites. The abundance and taxa richness of crustaceans have often been less, but usually not significantly less, at some stations near the outfalls. The collection of a variety of pollution-sensitive amphipods near the outfalls indicates that the diminished crustacean fauna may be due to a noncontaminant factor. Separate cluster analyses of mollusks and nonmollusks indicate that factors associated with water depth are more closely related to faunal similarity than proximity to the outfalls. Long-term temporal trends show increased macrobenthic abundance. In summary, the weight of evidence indicates the Sand Island and Barbers Point discharges have not caused substantial changes in the macrobenthos.
Occurrence of herbicides and their degradates in Hawaii’s groundwater
Li, Qing X., Eul-Chul Hwang, and Fengmao Guo
Hawaii, with its isolated insular location, unrelenting pest pressure, and complex volcanic geology, presents many unique challenges to protecting groundwater from pesticide contamination. The U.S. Environmental Protection Agency (EPA) estimated that about 10% of community water system wells and 4% of rural domestic wells in the U.S. contain at least one pesticide or pesticide degradation product (degradate) at the reporting limits of the survey (EPA 1990). Regular sampling of community water systems show pesticides and pesticide degradates in 68 of 457 drinking water sources in Hawaii (State of Hawaii Department of Health 1996). The previous monitoring primarily focused on fumigants such as ethylene dibromide and trichloropropane, triazine herbicides, and chlorinated insecticides such as dieldrin and lindane. The most frequently reported pesticides in Hawaii’s groundwater are fumigants used in pineapple fields, triazine herbicides used in sugarcane fields and termiticides. Agriculture in Hawaii is in a change from plantation to small family farms. Various pesticides have been used to control different pests. A recent study categorized a wide range of pesticides as “teachers” or “non-leachers” for a specific Hawaii hydrogeological setting.
This study was to monitor the occurrence of some herbicides found in groundwater in the continental U.S. in selected wells in Hawaii. These include alachlor, bromacil, dacthal, hexazinone, metolachlor, metribuzin, atrazine, ametryn and simazine and their degradates. Findings in this study have supported the log-transformed attenuation factor index ranking as a practical predication means to assist decision-making
Modeling hydrocarbon biodegradation in tidal aquifers with water-saturation and heat inhibition effects
El-Kadi, Aly I.
A model is developed for hydrocarbon biodegradation, which includes saturated and unsaturated flow, multi-species transport, heat transport, and bacterial growth processes. Numerical accuracy of the model was tested against analytical solutions. The model was also verified against laboratory results for a saturated-flow problem and reasonable match was obtained. Expressions are proposed for inhibition due to water content and temperature fluctuations. Bioactivities under cyclic water content variation were studied under no-flow conditions. A quantitative approach was used to reconcile some of the apparent contradictory conclusions regarding the efficiency of biodegradation of soils under wetting and drying conditions. The efficiency depends on the nature of the oxygenation process. For cases involving the presence of dissolved oxygen and the absence of O2 vapor, subjecting the soil to constant water content close to its optimal value for degradation is most efficient. However, wetting and drying can enhance degradation if O2 is only provided through aeration or direct contact between air and the medium. Also presented are the results of a typical field application of the model and a discussion of the effects of tides, saturation inhibition, and heat inhibition. Other inhibition factors, such as pH or salinity, can be easily incorporated in the formulation. The quantitative approach developed here can be used in assessing bioremediation not only in tidal aquifers but also in areas where water-table or temperature effects are of significance. The approach can be useful in the design of remediation strategies under water-flow or no-flow conditions involving water content and temperature fluctuations.
Hawaiian Phoronida (Lophophorata) and their distribution in the Pacific region
Bailey-Brock, Julie H., and Christian C. Emig
Five Phoronis species are found in Hawaiian waters. Three were recorded previously, and two others, P. muelleri and P. pallida, are added here. Phoronis ovalis (the smallest) and P. hippocrepia are perforant species forming burrows in coral rock, shells, and barnacle encrustations, and P. psammophila, P. muelleri, and P. Pallida are sand-dwellers. Species diagnosis in phoronids requires sectioning to estimate muscle formulas and arrangement of other internal organs. Included are a key to Hawaiian species based on visible external features (so not entirely accurate), description of each, and distribution in Hawaiian waters and the Pacific Ocean.
Morphology and life history of Ophryotrocha adherens sp. nov. (Polychaeta, Dorvilleidae
Paavo, Brian, Julie H. Bailey-Brock, and Bertil Akesson
An undescribed dorvilleid belonging to the genus Ophryotrocha, Chaparede & Mecznikow, has been collected in the harbor of Kyrenia, Cyprus, the harbor of Las Palmas, and the Canary Islands. It also has recently been reported from the Sand Island and Barbers Point sewage outfalls (Oahu, Hawaii) during an ongoing benthic biomonitoring program. Previous investigations of possible indicator species suggest it may be an outfall-associated species. The species has been continuously cultured since 1971 in Sweden and since 1993 in Hawaii. It has been documented by previous authors under the name Ophryotrocha adherens. These laboratory cultures have produced a profile of the species’ life history. The basic reproductive pattern, which includes a short-term free-swimming larva and brood protection within a flexible mucous cocoon, was revealed in a life table study. A full description of O. adherens morphology is presented here, including results of light and scanning electron microscopy of parapodia, setae, cilia, and dentition. Recent community studies have shown that O. adherens abundances decrease with increasing distance from primary treatment sewage outfalls over the past eight years. Rapid reproductive response to organic enrichment makes O. adherens a candidate for marine sediment bioassays.
Immunochemical detection of polycyclic aromatic hydrocarbons and 1-hydroxypyrene in water and sediment samples
Li, Kai, Lee Ann Woodward, Alexander E. Karu, and Qing X. Li
Several approaches were investigated to fully use an enzyme-linked immunosorbent assay (ELISA) for accurate measurement of polycyclic aromatic hydrocarbons (PAHs) and their degradation products in surface water and sediments collected from the Pearl Harbor and James Campbell National Wildlife Refuges (NWRs) in Hawaii. Water samples were extracted by solid phase extraction (SPE) while the sediments were extracted by supercritical CO2. Parent PAHs and 1-hydroxypyrene, selected as a marker, were quantitatively recovered with supercritical CO2 from sediments that were mixed with 5% Na4EDTA. Use of Na4EDTA or Na2SiO3 significantly improved recovery of 1-hydroxypyrene in sediments. Na4EDTA was more effective than Na2SiO3. The concentrations of PAHs as benzo[a]pyrene equivalents determined by ELISA were slightly higher than those determined by gas chromatography; mass spectrometry (GC/MS). Overestimation’ by ELISA over GC/MS was attributed to, at least in part, the presence of PAH metabolites including 1-hydroxypyrene which were detected by ELISA, but not quantified by GC/MS.
Sunlight inactivation of human enteric viruses and fecal bacteria
Fujioka, R.S., and B.S. Yoneyama
Three human enteric viruses (poliovirus, echovirus, coxsackievirus) suspended in seawater or buffer were stable for 6 hours in the absence of sunlight but were inactivated at the same rate in the presence of sunlight. Under summer sunlight conditions, at least 3 logs of these viruses were inactivated by one-hit kinetics, whereas under winter sunlight conditions, only 1 log of these viruses was inactivated by two-hit kinetics. Under these same conditions, 6 logs of E. coli were inactivated within 1 hour by one-hit kinetics under summer and winter conditions. In comparison, E. faecalis was inactivated by two-hit kinetics and only 2.5 logs of inactivation were observed after 4 hours of exposure to winter sunlight. Since human enteric viruses are considerably more resistant to sunlight inactivation than E. coli and moderately more resistant than E. faecalis, marine recreational water quality standards should be based on concentrations of enterococci and not on coliform bacteria. Since the mechanism and rate of inactivation of coliphage and human enteric viruses are similar, coliphages appear to be the best indicator for the presence of human enteric viruses in recreational waters, especially coastal waters where abundant sunshine is available.
Linear systems approach to subsurface pollutant transport analysis
Liu, Clark C.K., C. Ji, and D. Neupane
Comprehensive physically based models of chemical transport in soils consist of two nonlinear partial differential equations. An exact analytical solution for these equations is difficult to derive. A numerical solution, on the other hand, produces numerical dispersion and leads to unsatisfactory modeling results. For nonconservative chemicals in adsorptive soils, physically based modeling becomes even more complicated. Simplified models such as mobility index models have been proposed and used, but they are too simple to provide any in-depth understanding of the transport phenomenon. This study shows that by using a linear systems approach, transport characteristics of field soils can be simply described by an impulse response function. The fate and transport of chemical residues in the soil can then be readily determined by convolution integration. This study also shows that the impulse response function of a soil transport system takes the form of a gamma distribution function. Two multiple regression equations, which relate the two parameters of a gamma distribution function with the soil’s basic properties, were derived.
Turf irrigation in Hawaii using R-1 effluent: microbial and chemical Effects
Murakami, Gregory A., and Chittaranjan Ray
Secondary-treated, filtered, and chlorinated effluent (R-1 quality) blended with potable water was used for turf grass irrigation at the Hawaii Kai Golf Course on the island of Oahu, Hawaii. Blending was required because of the salinity level in the R-1 effluent. For control, only potable water was used for irrigation. Irrigation amounts varied with time based upon rainfall. Suction lysimeters were installed at 25-cm and 40-cm depths to collect soil-water samples. In addition, water samples from potable water and blended water storage impoundments were collected for analysis. All water samples were analyzed for nitrate, chemical oxygen demand, pH, conductivity, and fecal coliform bacteria density. Grass samples and soil samples were analyzed for fecal bacteria. Results indicated that fertilization of the turf affected the nitrate content of certain suction lysimeter samples. Conductivity of the leachate samples decreased with time, indicating possible dilution with rainwater. The most significant observation was the growth of fecal bacteria in leachate waters and open storage reservoirs. Grass and soil samples also showed the presence of fecal coliform bacteria. This indicates that fecal coliforms should not be used as indicator bacteria in tropical environments, where they are naturally present. For Oahu, using fecal coliforms as indicator bacteria can be a problem if R-1 effluent is used on areas overlying potable water aquifers. Clostridium perfringens, which is present in large numbers in wastewaters, may be a better indicator bacterium since it is not found in large numbers in the natural soil environment.
Soil: the environmental source of Escherichia coli and Enterococci in Guam’s streams
Fujioka, R., C. Sian-Denton, M. Borja, J. Castro, and K. Morphew
We have previously documented that faecal indicator bacteria (Escherichia coli, faecal coliform, enterococci) recommended by the U.S. Environmental Protection Agency (USEPA) to establish recreational water quality standards are naturally found in high concentrations in the surface and subsurface of soils in Hawaii. Rain, the source of all streams in Hawaii, washes the soil sources of faecal bacteria into all the streams of Hawaii, at concentrations which consistently exceed the USEPA recreational water quality standards. The objective of this study was to test the hypothesis that faecal bacteria are able to establish themselves in the soil environments of tropical islands by conducting the same study in Guam, a tropical pacific island with warmer temperatures and higher humidity than Hawaii. The same methods and study design used in Hawaii was used in Guam. The results of the study conducted in Guam revealed that all streams contain consistently high concentrations of faecal coliform, E. coli, and enterococci/100 ml which exceeded the old USEPA recreational water quality standard of 200 faecal coliform/100 ml as well as the new water quality standards of 126 E. coli /100 ml or 33 enterococci/100 ml. These same faecal indicator bacteria were recovered in high concentrations in surface and subsurface (18-36 cm depth) soil samples in Guam. Limited coastal water analysis showed that most coastal marine waters contain low concentrations of faecal bacteria but coastal water impacted by stream run-off showed elevated levels of faecal bacteria. The results of this study support the hypothesis that environmental conditions in the tropical areas of the world can support the growth and establishment of populations of faecal bacteria in the soil. Thus, soil becomes an environmental, no-faecal source of faecal indicator bacteria. These results indicate that USEPA water quality standards may not be directly applicable to tropical island environments.
Conservation zoning for groundwater source protection
Lau, L. Stephen, and John F. Mink
Conservation zoning in Hawaii dedicates lands for the protection of watersheds and water sources. The designated lands include forest and vacant areas but exclude areas for major uses such as urban and agricultural. This has been the practice on the island of Oahu, Hawaii, USA (land area 593 mi2 [1535 km2]; 1990 population about 840,000) since the 1920s. The sizable conservation district (about 40 percent of the island land) in high-rainfall mountains ensures the recharge needed for groundwater sources that provide over 99 percent of the drinking water supply for Oahu. Is this policy wise, or is it too inflexible and draconian to be applicable to water source protection for other communities?
This paper presents the hydrological paradigm that optimal groundwater recharge takes place in undisturbed natural forests in Hawaii and discusses aquifer sustainable yields and groundwater quality. The Hawaii land use law, which was the first in the United States to regulate land use on a statewide basis, and its ramifications are also discussed. Finally, the recent (1992) five-year review of the conservation districts is presented from the hydrological perspective. The review not only confirms the necessity of the existing conservation districts but also recommends considerable expansion, especially in certain areas of the sparsely populated neighbor islands that are threatened with urbanization. The current status of the recommended changes is discussed.
Integrating an intermittent aerator in a swine wastewater treatment system for land-limited conditions
Yang, P.Y., and Zhiyu Wang
A full-scale swine (300 pigs) waste treatment system–including a solid/liquid separation unit (3m3) with solids holding tank (1.2 m3) and a liquid holding tank (20 m3), two anaerobic reactors (10 m3 each) in series, an intermittent aeration unit (20 m3), and a sluge dewatering bed (17 m2)–was used to investigate the impact of integrating an intermittent aeration unit on the overall process performance of the swine waste treatment system. The intermittent aeration unit was used for the treatment of a combination of raw liquid manure and anaerobically treated concentrated manure. Four optional ratios of aeration time to nonaeration time of 60:36, 5:1, 4:2, and 3:3 hours were investigated. At a hydraulic retention time of 3.2 days and a ratio of aeration to nonaeration of 3:3 hours, the removal efficiencies for 5-day biochemical oxygen demand (BOD5), total-nitrogen (T-N), total suspended solids (TSS), and total-phosphorus (T-P) were 98.0%, 92.4%, 95.6%, and 59.4%, respectively, for the intermittent aeration unit. Effluent concentrations of BOD5, NO–3-N, NH+4-N, and TSS were 35+12, 2.6+0.8, 36+28, and 78+13 mg/l, respectively. The impact of integrating an intermittent aeration unit in the overall swine waste treatment system, which included solid/liquid separation, anaerobic treatment, and final sedimentation/polishing units is apparent from its high treatment efficiency for BOD5 and T-N. Economic evaluation of the swine waste treatment system integrating an intermittent aeration unit was conducted based on 300, 1,000, 2,000, 3,000, and 5,000 pigs. It was found that the utilization of biogas and digesting sluge is essential for the benefit or the profit of operating this treatment system. Integrating the intermittent aeration unit in the swine waste treatment system provides reduction of energy consumption cost and reuse/disposal of treated wastewater without causing deterioration of environmental quality. The integrated system also provides the possiblity of developing a fabricated-packaged treatment plant of a central swine waste processing system for application in land-limited tropical/subtropical areas.
Na4EDTA-assisted sub-/supercritical fluid extraction procedure for quantitative recovery of polar analytes in soil
Guo, Fengmao, Qing X. Li, and Jocelyn P. Alcantara-Licudine
Supercritical carbon dioxide (SC-CO2) is effective in extracting nonpolar and slightly polar chemicals from soils. However, pure SC-CO2 is unsatisfactory for recovering polar chemicals in soils. A simple supercritical fluid extraction (SFE) procedure was developed to quantitatively recover polar and nonpolar chemicals from soils. The polar chemicals tested were aromatic acids and phenols. The nonpolar and slightly polar chemicals used as model compounds were common pesticides and environmental pollutants such as polycyclic aromatic hydrocarbons. The procedure required pretreatment of the samples with 15% water (g/g), 5% (ethylenedinitrilo)-tetraacetic acid tetrasodium salt (Na4EDTA)(g/g), and 50% methanol (ml/g) prior to extractions using SC-CO2 at 60oC and 34.5 MPa. Recoveries ranged from 90% to 106% for the aromatic acids using Na4EDTA-assisted SFE compared with only 7% to 63% recoveries of the corresponding chemicals when no Na4EDTA was used. The method quantitatively extracted 2,4-D and its close analogues aged in the soil for 2 to 30 days. The Na4EDTA-assisted SFE was also adequate for extracting phenolic analytes, including picric acid and pentacholorophenol, with recoveries from 85 % to 104%. Na4EDTA is a good enhancer for extraction of the 29 analytes representing a wide range of polarity from the soil using SC-CO2. The method is valuable for the analysts of parent pollutants and transformed products, particularly oxygen-borne metabolites in the environment.
Hawaii rainwater catchment systems development: Draft guidelines
Fok, Yu-Si, Leroy F. Heitz, and Henry H. Smith
The objective of this paper is to present a draft of Hawaii Rainwater Catchment Systems (RWCS) Development Guidelines for the conference participants and the readers of this paper.
The purpose of this paper is (1) to present research results of our investigations as outlined in the USGS Collaborative Research Project (09/01/97 to 08/30/99) to form the basic approach of the RWCS development guidelines, (2) to assess the abilities of RWCS users to comply with the items that have been proposed in 1994 Hawaii House Concurrent Resolution no. 214, and (3) to show the Draft Hawaii Rainwater Catchment Systems Development Guidelines which may be adopted by the public sector to regulate RWCS development and management.
The objective of this paper is to present a brief draft of the guidelines for Hawaii rainwater catchment systems (RWCS) development for conference participants and readers of this paper to review and comment on. This paper is divided into four major parts: (1) results of our investigation of this subject, (2) assessment of RWCS users ability to comply with guidelines developed under House Concurrent Resolution No. 214 (Hawaii House of Representatives, 1994), (3) discussion and evaluation, and (4) conclusions.
UV disinfection: To pilot or not to pilot?
Moreland, Victor, Audrey Asahina, Tua Unutoa, and Roger Fujioka
Honolulu evaluates and compares established wastewater treatment systems with newer technology. The effectiveness of low- and high-intensity ultraviolet lamp technology to disinfect unfiltered secondary effluent is evaluated in this pilot-scale study. One goal was to determine the true UV dose required to disinfect indicator bacteria in unfiltered secondary effluent using a collimated beam unit. Another focus was to correlate the effectiveness of all three UV systems while verifying water quality for each.
Political economy of protecting unique recreational resources: Hanauma Bay, Hawaii
Mak, James, and James E.T. Moncur
The impact of tourism growth on the environment has become an increasingly important public issue in travel destinations. We review Honolulu’s recent experience in designing management strategies to protect one of its most popular, unique, and endangered natural recreational resources, Hanauma Bay Nature Park. We explain why Honolulu City Council members first adopted nonprice rationing techniques to reduce visits in the park and later added an admission fee only to replace it with a lower and less efficiency-enhancing fee structure. Lawmakers desire (i) a quality environment, (ii) to collect economic rents (i.e., achieve economic efficiency) for the benefit of the general public, and yet must (iii) achieve a political equilibrium. As Honolulu’s experience demonstrates, goals (i) and (ii) often conflict with goal (iii), yielding typically a second-best outcome. Efficiency can be attained only if it is also consistent with attaining political equilibrium.
Optimal allocation of ground and surface water in Oahu: Water wars in paradise
Moncur, James, Jim Roumasset, and Rodney Smith
Despite abundant rainfall and groundwater resources, the State of Hawaii has managed to erect so many barriers to efficient use that serious conflicts have erupted over use rights to water. In what is currently the most prominent battle, environmental and agricultural interests of windward Oahu are pitted against agricultural producers on the leeward side over the allocation of aqueduct water in the Koolau Mountains. To inform this debate, a model of conjunctive use is constructed and optimal allocation of ground, surface, and aqueduct water computed. Optimal use of the aqueduct water is as a substitute for groundwater. This postpones the eventual, expensive use of desalination, thus benefiting future users. By making use right fully transferable and charging current users water’s true opportunity cost, both windward and leeward users would be winners.
An on-farm swine waste management system in Hawai‘i
Yang, P.Y., and C. Gan
A prototype of a swine waste treatment system for a 20- to 25-sow operation was investigated for its potential for odor control, byproduct utilization, and treated wastewater reuse. The high solid portion of the swine waste ranging from 4% to 8% total solids was treated and stabilized by the anaerobic process with a hydraulic retention time (HRT) of 32 days. The diluted liquid portion from raw and anaerobically digested swine wastewater was effectively treated by the aeration and sedimentation units with an HRT of 3 and 4 days, respectively. The overall removal efficiency of 89% to 95.4% for total chemical oxygen demand (TCOD), 82.3% to 88.5% for total Kjeldahl nitrogen and 81.2% for total-phosphorus was achieved. The treated effluent was reused for irrigation of pasture without any negative impact of odor problems. Also, it meets the requirements of the wastewater reuse criteria, R-3, issued by the Hawai‘i Department of Health. The economic analysis was conducted by calculating the net present worth. It was found that the capital cost is the major cost for the proposed treatment system. The reuse of biogas as energy and sludge as fertilizer are the key factors as to whether or not it will turn the treatment system into a profit. More than 830 pigs (or approximately 80 sows) are required to achieve the breakeven point for the application of the swine waste treatment system. Thus, a profit could be made with the application of this treatment system to more than 830 pigs if the comprehensive utilization of methane gas and stabilized sludge could be realized.
Entrapped mixed microbial cell process for combined secondary and tertiary wastewater treatment
Yang, P.Y., and K. Cao
An entrapped-mixed-microbial-cell process was investigated for the simultaneous removal of carbon and nitrogen in a single bioreactor with influent COD/N ratios varying from 4 to 15 and with influent alkalinity concentrations of 140 mg/l and 230 mg/l as CaCO3. The alternated schedules of the intermittent aeration was operated for two different sizes of carriers (i.e., medium carrier is 10x10x10 mm3 and large carrier is 20x20x20 mm3). It was found that the medium carrier achieved higher removal of nitrogen, COD, and BOD5 at 92%, 95%, and 97%, respectively. This was under the operation of a hydraulic retention time of 12 hours, 0.5 hour of aeration/ 2 hours of nonaeration, and a COD/N ratio of 15 in the influent. The influent alkalinity concentration of 140 and 230 mg/l as CaCO3 has minimum effect on the removal of carbon and nitrogen. However, the oxidation-reduction potential, ranging from -100 to 300 mV, provides better nitrogen removal efficiency to maintain the total nitrogen (NO–3-N, NO–2-N, and NH+4-nitrogen) at less than 10 mg/l when a COD/N ratio of 10:15 is maintained in influent. The higher ratio of COD/N in the influent performs better nitrogen removal efficiency; i.e., COD/N of 15>10>7>4. It is apparent that the EMMC process is technically feasible for the simultaneous removal of carbon and nitrogen under the operation of an alternated aeration/nonaeration schedule in a single bioreactor. Ultimately, it can replace or upgrade the existing combined secondary and tertiary wastewater treatment plant in one bioreactor and provide simple maintenance and operation.
RWCS development guidelines: A bridge for private and public sectors’ partnership
The number of rainwater catchment system (RWCS) users has increased all over the world in recent decades. The reasons are many, but the major ones are (1) the concentration of people in cities of developing countries and (2) the greatly increasing demand for water for food production in rural areas, especially in arid and semiarid regions. The population in cities of developing countries has increased from 773 million in 1950 to 2.6 billion in 1995, a 336% increase in just 25 years. This increase has caused frequent water shortages, resulting in the need for more RWCS development. The public sector has become greatly concerned about RWCS development because the private systems were built without building permits or without following building codes. When building private RWCS, individuals need to comply with regulations developed by governmental agencies to ensure that the public health and safety of all citizens are not compromised. Hence, there is a definite need for RWCS development guidelines to bridge the different viewpoints of the private and public sectors. This paper presents the approach that a set of guidelines would be an important bridge for the partnership between the two sectors for RWCS development and management.
Rainwater catchment systems development guidelines
Most rainwater catchment systems (RWCS) are developed and managed by private users. From the public safety standpoint, RWCS are a concern because the construction of the water supply systems is unregulated since no building code or building permit is required at present. From the public health standpoint RWCS are often a big concern because the water quality is not monitored for potable uses. According to Wilken (1995), the number of people living in urban areas jumped from 737 million in 1950 to 2.6 billion in 1995. The urban share of the total population increased from 29% to 45% in just 45 years. More than 50% of the developed countries’ populations were already urban by 1950; therefore, the increase in urban populations in recent decades largely took place in developing countries. The rapidly increasing population rate has a great impact on the public utilities. A great demand in such a short time causes frequent water shortages. This becomes a problem because traditional water supply development requires sufficient time to plan to acquire water rights and right-of-ways, and to obtain permits and funding. Most immigrants to cities are poor and are trying to earn a living in the city. The water shortage problems are just part of their daily struggles. RWCS development is a suitable solution for them. This paper presents a set of RWCS development guidelines based on the affordability principle in order to provide a common ground for the public and private sectors to solve the water shortage problem.
Status of RWCS development and progress of IRCSA.
The development of rainwater catchment systems (RWCS) has been gaining great momentum worldwide in recent decades. This is partly due to the United Nations General Assembly’s proclamation of 1981-1990 as the International Drinking Water Supply and Sanitation Decade and partly due to the series of international conferences on rainwater catchment systems that began in June 1982. To date, eight conferences have been held at about two-year intervals in different cities of the world to promote RWCS development. A brief description of the Thailand Jar Project, an example of a national project that aimed to provide a safe and adequate drinking water supply for the country’s rural residents, is included in this paper. Highlights of the progress in RWCS development made by the International Rainwater Catchment Systems Association, which was formed at the fourth conference in August 1989, are also included.
Near-field mixing of wastewater effluent from the Pali marine outfall, Northern Taiwan.
Liu, Clark C.K., Jing Li, and Huashan Lin
The Pali marine outfall, an important element of the Tansui River water pollution control project in Northern Taiwan, was designed to discharge wastewater at a rate of 37 m3/s, or about 840 mgd, into Taiwan Strait. To minimize the potential adverse impact of this discharge on the marine environment requires a thorough understanding of effluent mixing in receiving water. Generally, the negative environmental impact would be small if the waste materials in an effluent plume could be significantly diluted. The magnitude of near-field mixing depends on both waste effluent characteristics and ambient ocean conditions. Relevant ocean conditions include ocean current, density stratification, and ocean waves. The effect of ambient ocean waves on near-field mixing has been ignored by almost all existing mathematical models. In this study, the popular near-field mixing model UM was modified to include wave effect. The modified model was then used to predict effluent mixing in the Pali outfall area. Simulation results show that the minimum required initial dilution ration of 100 to 1 can be achieved when the ambient current velocity is 2 m/s or higher. Further, the simulation results indicate that ambient waves play an important role in near-field mixing. When the amplitude of ambient ocean waves is 2 m or higher, the Pali outfall effluent can achieve the required dilution, even in the absence of ocean currents.
A prototype small swine waste treatment system for land limited and tropical application
Yang, P.Y., E. Khan, G. Gan, D. Paquin, and T. Liang.
A prototype of a 300-pig waste treatment system was constructed at the animal research farm of the University of Hawai’i. The system includes a solid/liquid separation unit (12 m3), and one combined rock bed filter and aquatic plant reactor (20 m3). Based on the current results of a 240-pig operation. methane gas production and total solids (TS) reduction are 0.75 m3/m3/day and 72.7%, respectively, at a loading rate of 3.09 kg TS/m3. The aeration unit provides a TCOD and NH3-N reduction of 94% and 91%, respectively. The rock filter achieves a TCOD, NH3-N, and NO3-N reduction of 32.8%, 26.8%, and 68.4%, respectively. The annual cost for each of the treatment components is presented. It is very useful for the aplication of each treatment unit for the various needs of each pig farm.
An on-farm swine waste treatment system for odor control, byproduct recovery and treated wastewater reuse in Hawaii.
Yang P.Y., C. Gan, D.G. Paquin, and T. Liang
A prototype of swine waste treatment system for 240- to 240-pig operation was investigated for its potential for odor control, byproduct utilization, and treated wastewater reuse. It was found that the high solid portion of the swine waste rangine from 4% to 8% total solids could be treated and stabilized by the anaerobic process with a hydrulic retention time (HRT) of 32 days. The diluted liquid portion from raw and anaerobically digested swine wastewater could be effectively treated by the aeration and sedimentation units with an HRT of 3 and 4 days, respectively. The overall removal efficiency of 89.0% to 95.4% for total chemical oxygen demand, 82.3% to 88.5% for total Kjedahl nitrogen, and 81.2% for total phosphorous could be achieved. The treated effluent could be reused for irrigation of pastures without any odor problems. Also, it meets the requirements of the wastewater reuse criteria, R-3, issued by the Hawai’i Department of Health. An economic analysis was conducted by calculating the net present worth. It was found that the capital cost for equipment is the major expense item for the proposed treatment system. The reuse of biogas as energy and sluge as fertilizer was determined to be the key factor in turning the treatment system into a profit operation. Also, it was found that the farm operation would require more than 830 pigs for the swine waste treatment system to achieve a breakeven point. Thus this treatment system could result in a profit by centralizing the hog operation and by fully utilizing the produced methane gas and digested sluge.
Conservation zoning for groundwater source protection.
Mink, John F., and L. Stephen Lau
Conservation zoning in Hawaii dedicates lands for the protection of watersheds and water sources. The designated lands include forest and vacant areas but exclude areas for major uses such as urban and agricultural. This has been the practice on the island of Oahu since the 1920s. The sizable conservation district (about 40% of the island land) in high-rainfall mountains ensures the recharge needed for groundwater sources that provide over 99% of the drinking water supply for Oahu. Is this policy wise, or is it too inflexible and draconian to be applicable to water source protection for other communities? This paper presents the hydrological paradigm that optimal groundwater recharge takes place in undisturbed natural forests in Hawaii and discusses aquifer sustainable yields and groundwater quality. The Hawaii land use law, which was the first in the United States to regulate land use on a statewide basis, and its ramifications are also discussed. Finally, the recent (1992) five-year review of the conservation districts is presented from the hydrological perspective. The review not only confirms the necessity of the existing conservation districts but also recommends considerable expansion, especially in certain areas of the sparsely populated neighbor islands that are threatened with urbanization. the current status of the recommended changes is discussed.
Accounting-induced distortion in public enterprise pricing.
Moncur, James E.T., and Richard L. Pollock
Municipal water utilities commonly aim to set prices at average cost. Because of various omissions and owing to inflation, unadjusted accounting data understate the economic costs of fixed assets and thus generate inefficiently low prices and high consumption rates for the output of these enterprises. We investigate the nature and extent of undercosting and underpricing for a group of large urban water utilities in the United States. Economic costs appear to be significantly greater than the corresponding accounting measures for the cases studied.
Rainwater catchment systems: Development and guidelines.
Rainwater catchment systems (RWCS) have been in use for centuries. However, since most have been developed by users with private funds, few public sector decision-makers acknowledge the contribution RWCS have for water conservation and for water supply by including RWCS construction guidelines in their building code. Due to the great progress in the environmental protection movement and because public water supply systems have shown their inability to satisfy the ever-increasing demands for piped water, the need for RWCS development guidelines that take these factors into consideration becomes evident. This paper aims to document existing RWCS guidelines; to report the current progress of RWCS guideline development in Hawaii; to present problems related to RWCS guideline development, especially those problems related to the affordability of the RWCS development in Hawaii; and finally to suggest ways for establishing universal RWCS development guidelines. Using the guidelines developed for Hawaii as an illustration, this paper points out the importance of conducting a cost analysis on items included in RWCS guidelines. To ensure that they are complied with socially and economically, guidelines must be user-friendly and affordable.
Rainwater catchment systems as an important part for integrated resources development in arid and semiarid regions.
From the viewpoint of regional resources development, water is a limiting resource in arid and semiarid regions. Rainwater is a natural renewable resource which should be harvested and preserved for beneficial uses. Especially in arid and semiarid regions, rainwater should not be allowed to be lost in the hydrologic cycle-such as through evaporation, interception, infiltration, and transpiration-without the benefit of production. This is because if water is available, many other resources can be developed more fully. This paper shows that rainwater catchment systems (RWCS) are a vital means for integrated resources development in arid and semiarid regions, where systems should not only be developed by the public sector but also be constructed by the private sector. A collective water harvesting effort conducted on a regional basis should be the water policy in the 21st century. From the micro-viewpoint, this paper demonstrates that RWCS can be a solution to the water shortage problem by providing a domestic water supply, irrigation for garden crops/landscapes, water for firefighting, and water for agricultural production. The concept of macro-viewpoint in terms of RWCS use in integrated resource development is introduced and its importance explored.
Water balance, climate change and land-use planning in the Pearl Harbor basin, Hawai’i.
Giambelluca, Thomas W., Mark A. Ridgley, and Michael A. Nullet
The Pearl Harbor basin on the tropical oceanic island of Oahu, Hawai’i, exhibits extreme climate gradients, rapid land-use change, and groundwater use near sustainable yield. The basin’s water usage and groundwater recharge, and hence water yield, are strongly influenced by the spatial distribution of land use. Current recharge is expected to drop about one-eighth with the demise of remaining sugarcane and pineapple. Evidence suggests that lower rainfall and increased evaporation may well accompany warmer periods in Hawai’i, and water-balance simulations indicate many scenarios having a significant decrease in available water. Land-use planners can use such results in tandem with multiobjective optimization models to generate alternative land-use plans and show trade-offs among objectives.
Development of guidelines for construction of rainwater catchment systems in Hawaii.
This paper presents the past efforts of the public sector to create guidelines for RWCS development and, accordingly, provides an assessment of the acceptability of these guidelines. It also seeks support in obtaining funds to perform a cost analysis on the guidelines requested by House Concurrent Resolution No. 214, as included in a master’s degree thesis by Todd Boulanger (1994).
Linear systems theory and modeling of river water quality
Liu, Clark C.K.
The water quality of a polluted river can be improved either by increasing the river’s self-purification ability or by reducing waste loadings the river receives. Traditional physically based water quality models do not evaluate separately a receiving river’s purification ability and the effect of waste loadings; thus, they are less than desirable as an analytical tool of water quality management. An alternative river water quality modeling approach based on the linear systems theory is explored in this study. In a linear systems model, a receiving river’s self-purification ability is represented completely by the model’s impulse response function, whereas waste loadings the river receives are represented by the model’s input function. The two functions can be evaluated separately. Furthermore, the water quality condition is the system output and can be readily calculated by a simple convolution integration of impulse response function and input function. The linear systems model as a useful water quality management tool is demonstrated in this paper by applying it to a study of dissolved oxygen variations in a river which receives both point-source and nonpoint-source waste loadings.
Sand, Soil, and Pigeon Droppings: Sources of Indicator Bacteria in the Waters of Hanauma Bay, Oahu, Hawaii
Oshiro, Robin and Roger Fujioka
To investigate the deteriorating bacteriological water quality of Hanauma Bay, Hawaii, samples of shoreline water, sand, land runoff, and mongoose and pigeon droppings were analysed for fecal coliforms, E. coli and enterococci. The results indicate that the major sources contributing to periodic high levels of bacteria in the waters of the Bay are contaminants of the beach sand, such as pigeon feces.
Detection of Legionella Bacteria in Sewage by Polymerase Chain Reaction and Standard Culture Method
Roll, Bruce M. and Roger S. Fujioka
Legionella bacteria are ubiquitous in environmental waters. Only a few species ofLegionella , especially, L. pneumophila are pathogenic to humans and cause a sometimes fatal Legionnaires disease as well as a less fatal disease called Pontiac fever. The presence ofLegionella in sewage and aerosolized sewage is the subject of this investigation because reuse of sewage may involve the exposure of people to aerosolization, the mode of transmission ofLegionella bacteria. The objective of this study was to determine the prevalence of Legionella species and L. pneumophila in wastewater and their fate after various stages of treatment. The polymerase chain reaction (PCR) and standard culture method were utilized to detectLegionella species and L. pneumophila. PCR results indicated that Legionella species were present at levels > 103 cells / ml during all phases of sewage treatment including chlorinated effluents. Culture results indicated levels at least one log lower than seen with PCR. Legionella species were also recovered from air samples collected from secondary aeration basins at levels < 103 cells/ml. PCR was shown to be the most rapid and sensitive method for detectingLegionella in sewage.
Sustainable tourism development: Managing Hawaii’s ‘unique’ touristic resource – Hanauma Bay
Mak, James and James E.T. Moncur
Journal of Travel Research 33(4):51–57
The impact of tourism growth on the environment is an increasingly important public issue in travel destinations. However, there has been very little research focusing on the evaluation of management strategies for the sustainable development of unique touristic sites. Hawaii has one such unique site in Hanauma Bay Nature Park. In this case study, we describe and evaluate the recent Honolulu City and County management plan for Hanauma Bay and suggest several criteria for the evaluation of management strategies for unique touristic resources. We conclude that Hanauma Bay is a partial success story of sustainable recreational resource management. It is argued that efficiency and benefits principles suggest that visitors to Hanauma Bay be required to pay an admission fee to ration the use of this scarce recreational resource and to generate revenues to fund park services.
Injected helium technology for environmental near-shore water monitoring
Lau, L.S., and A.I. El-Kadi
Use of dissolved helium as a water environment-tracer has been documented by Gupta et al. (Ground Water 32(1), 1994; Hydrological Sciences Journal 93(2), 1994). Helium has many unique attributes that make it attractive for use as a tracer. They include a low background atmospheric concentration, a low molecular diffusion constant in water, a moderate solubility in water, and an easy availability at a low price. This study explored the use of the helium tracer in a shoreline site in Kona, Hawaii. The site is used for ocean thermal energy conversion and for aquacultural operations. Waters are disposed of in a ditch near the shoreline. Continuous monitoring data regarding various chemicals and temperature exist for a number of wells. The specific objectives are (1) to assess the transport processes in a trenchwater-groundwater system and (2) to understand the hydrogeology of the complex system through helium data, extant data, and modeling. Dissolved helium is introduced with return water discharged into a trench, and water is sampled from a monitoring well. The model used allows for density-dependent flow and chemical transport.
Assessment of effects of deep-water, sewage effluent discharge on a near shore, tropical benthic community, Honolulu, Hawaii.
Nelson, Walter G., Julie H. Bailey-Brock, William J. Cooke, and E. Alison Kay
The benthic infaunal community near the ocean outfall diffuser discharging wastewater from the city of Honolulu was sampled from 1986 through 1994. Abundance, number of species, and the overall species composition of the benthic infaunal community showed no changes attributable to an effect of effluent discharged from the diffuser. Both biological and physical (sediment grain size, total organic carbon, total Kjeldahl nitrogen) parameters showed no indication of an accumulation of organic matter on the bottom at the stations near the diffuser. Our studies indicate that there has been little alteration of the benthic community, even at stations immediately adjacent to the Sand Island Ocean Outfall diffuser.
A survey of selected coral and fish assemblages near the Waianae Ocean Outfall, Oahu, Hawaii, 1994
Russo, Anthony R.
In 1994, coral growth and fish abundance were monitored at three stations located at and in the vicinity of the Waianae Ocean Outfall. This report summarizes the results of that survey and comparatively analyzes the data with data collected in previous sampling years. No significant deleterious effects resulting from outfall operation and discharge were seen on the biological community at the stations surveyed.
The role of RWCS in 21st century water management.
Rainwater catchment systems (RWCS) are age-old water supply systems that will regain their position in diverse forms to complement centralized public water systems in the 21st century. Regardless of the level of development, many public water supply systems have already shown their inability to expand fast enough to meet the ever-increasing demand for water. As a result, water management decision makers have made efforts to find complementary ways of providing and conserving water. RWCS stands out as a practical solution. Users could develop their own RWCS to become self-sufficient in water, or at least to alleviate water shortage impacts. This paper explores the role of RWCS in 21st century water management with viewpoints from the public and private sectors reflecting social, economic, environmental, and institutional concerns. Also, this paper proposes the integration of RWCS with other renewable resource collection systems in designing new sustainable structures for the 21st century.
Organic contamination of groundwater in Hawaii: A learning experience revisited.
Lau, L. Stephen, and John F. Mink
A 12-year experience of regulatory actions and investigative research of nonpoint-source pesticide contamination of potable aquifers in Hawaii, USA, offers policies and technologies for use by others to forecast or meet similar contingencies.
In 1983, Hawaii, the beautiful tropical volcanic islands in the Pacific Ocean, met an unexpected crisis of unprecedented, large-scale contamination of the Pearl Harbor aquifer, the all-important drinking water source for the island of Oahu (Lau et al., 1987; Lau and Mink, 1987). The contamination was caused by volatile organic chemicals -l,2-dibromo-3-chloropropane (DBCP), ethylene dibromide (EDB), and 1,2,3-trichloropropane (TCP) – that had been used with approval as pesticides (nematocides) for pineapple agriculture for up to 35 years. Another use of EDB is as an additive to aviation gasoline. Military records show many major spills. The basalt aquifers, which are highly permeable with a regional hydraulic conductivity value of 500 m/day, consist of numerous thin (3 m), discontinuous, inhomogeneous layers of lithified lava flow. The water table is deep -195-265 m below ground surface at Mililani. Abstract truncated.
Sustainable rural water supply: Rainwater catchment systems
Fok, Yu-Si, Kyung H. Yoo, and Todd A. Boulanger
Rainwater catchment systems are regaining their reputation as a viable means of providing a sustainable water supply in rural areas and urban centers. In the United States, more than 250,000 rainwater catchment systems are scattered in the rural areas of many states. The number of such systems per state ranges from 100 in Vermont to 80,000 in Kentucky. This paper presents the recent progress of rainwater catchment system development. Requests for maintenance and operation guidelines by state legislatures are positive trends to promote the use of rainwater catchment systems in rural and urban areas. The prospect of incorporating rainwater catchment systems in 21st century buildings as part of renewable resources collection and utilization systems is also presented.
Rainwater harvesting: A practical means for water resources development and management in arid countries.
Fok, Yu-Si, and Show-Chyuan Chu
This paper presents examples of recent rainwater catchment system development in urban and rural areas. It also cites the importance of a national policy on rainwater harvesting and shows a matrix relating per capita annual average income with the types of water supply systems that are affordable by water users. This paper also explains that an ideal situation exists for private ownership of a rainwater harvesting system. This brings back the tradition of users managing their own water supply and not relying on the public water supply system. This is especially important in arid countries. Water is life! This paper also points out that the trend of 21st century buildings is for their construction to be in harmony with the environment. Natural renewable resources provided by mother nature should be beneficially collected and utilized by each building; in other words, each building should be constructed to serve as collectors and conservers of water and energy.
An analytical groundwater modeling approach for natural resources utilizing GIS
Oloufa, A.A., A.I. El-Kadi, A.A. Eltahan, and H.U. Malik
Successful water resource management requires the availability and synthesis of data from a multitude of sources. The system should also be capable of retrieving data related to these aspects in a format suitable for analysis by various simulation models. The objective is to store the required data pertaining to the various water and environmental resources in a flexible format that is simple to update, and to utilize a technology capable of linking the various parameters in an intuitive visual format. The technology of geographical information systems (GIS) offers such an approach. This paper discusses the design, development, and implementation of a GIS for water resources information management and modeling. Ease of use, portability, and data shareability are some of the major factors considered in the design of our system. For this pilot project, databases for soil types, water wells, aquifer classifications, rainfall rates, and streams are used as the underlying databases. Utilization of the GIS as a shell for analytical groundwater modeling is also presented.
Simulation of 1,3-dichloropropene in topsoil with pseudo first-order kinetics
Lin, Pengzhi, Clark C.K. Liu, Richard E. Green, and Randi Schneider
For fast-degraded chemicals such as 1,3-dichloropropene (1,3-D), their long persistent time in topsoils cannot be explained by the ordinary first-order kinetics of biodegradation that is commonly used in the simulation of chemical transport in soils. The Monod kinetics of biodegradation, which is usually defined as the mathematical relationship between the residual concentration of the growth-limiting substrate and the specific growth of degraders in laboratory reactors, was found to be responsible for the phenomenon of “decelerated biodegradation.” To take advantage of both the simplicity of first-order kinetics in transport modeling and the realistic description of Monod kinetics for a physical situation, a simplified method was used to represent Monod kinetics with the corresponding pseudo first-order kinetics. Pseudo first-order constants fitted with Monod kinetics were later substituted into the transport model. A satisfactory agreement between field measurement and simulated results using these constants was achieved.
Land-use planning and water resources in Hawaii under climate change.
Giambelluca, T.W., M.A. Ridgley, and M. Nullet
The Pearl Harbor basin on the tropical oceanic island of O’ahu, Hawai’i, is characterized by extreme climatic gradients, a fragile hydrolic system, and rapid land-use change. With all the management problems posed by those attributes, planners must now also consider the effects upon the regional hydrolic system due to possible climatic change. This paper describes an ongoing modeling effort to design and evaluate alternative land-use patterns under present and possible future climates. First, the paper focuses on the hydrogeological effects of climate change by estimating such possible effects through the application of a water-balance simulation model to each of 49 different climate scenarios. Evaporation is estimated to increase if temperature increases. Water-balance model runs demonstrate that for an increase of potential evaporation of 10%, even an increase in rainfall of 10% may still result in a significant decrease in available water. The problem of incorporating such findings into planning models is then addressed, with the discussion centering on the applicability of interactive multiobjective optimization. Reference-based programming techniques, perhaps utilizing some notions from fuzzy and stochastic programming, are considered especially suitable.
Assesment of four rainwater catchment designs on cistern water quality
Faisst, Eric W., and Roger S. Fujioka
This paper reports on an experiment in which rainwater was collected from the same corrugated metal roof of a given building using for different collection designs, eah with an identical 55-gallon plastic cistern tank as the catchment device. The four variations in design were a covered tank with screen device (Gutter Snipe), a covered tank with screen and foul-flush diverter, a covered tank with sceen and sand/gravel/charcoal filter, and an uncovered tank as a control. The drinking water quality of the four cisterns was evaluated by testing for concentrations of bacteria (total bacteria, total coliform, fecal coliform, and hydrogen sulfide producing bacteria), conductivity, turbidity, PH, and phosphates. The results indicated that tank 4 (samd/gravel/charcoal filter) demonstrated the lowest levels of indicator bacteria, ranging from 0 to 6 fecal coliforms per 100 ml (average of 1.3 CRU/100 ml); followed by tank 3 (foul flush) witha range of 0 to 168 CFU/100 ml (average of 17.8 CFU/100 ml); tank 2 (screen only) with a range of 0 to 388 CFU/100 ml (average of 51 CFU/100 ml); and tank 1 (uncovered) with a range of 0 to 2.59 x 104 CFU/100 ml (average of 2340 CFU/100 ml). However, concentrations of at least one of the three fecal indicator bacteria (total coliform, fecal coliform, and hydrogen sulfide producing bacteria) were often recovered from these waters, indicating that the systems designs were not able to meet U.S. microbiological drinking-water standards. All four systems were below the maximum turbidity level of 5 NTU established for individual sources. These cistern waters were also determined to have very high concentrations of total bacteria, always exceeding 500/ml, the minimum level at which interference with the recovery of total coliform bacteria has been reported. Fecal (44.5oC) and total (33.5oC) coliform results were compared with the hydrogen sulfide MPN method (room temperature). The hydrogen sulfide test correlated better with fecal coliform results as compared to talk coliform results after a 24-hour incubation period.
Guidelines and microbial standards for cistern waters.
Fujioka, Roger S.
Despite the availability of information on how best to design, build, and maintain rainwater cistern systems to ensure adequate water quality, few people follow these guidelines. Studies in Hawaii and elsewhere reveal that most cistern owners have not heard of foul-flush devices, do not clean their water collection/resevoir tanks at regular intervals, and do not disinfect their waters. In addition, many do not use filters. As a result of these practices, most cistern waters don not meet the U.S. Environmental Protection Agency bacteriological standards for drinking water. The poor quality of cistern waters in Hawaii is not due to insufficient education of the owners, to poor sanitary conditions, or to the use of makeshift materials to construct the cistern systems. Worldwide, the quality of most cistern waters has not been determined, as such systems are regarded as private and many countries do not require the monitoring of cistern water quality. However, available information indicates that most cistern waters cannot meet microbial standards. Implementation of guidelines for cistern systems will improve water quality, but waters may never consistently meet EPA drinking-water standards. Most cistern waters can be determined to be free of ontamination from human fecal wstes, and the risks associated with water containing nonhuman sources of indicator bacteria should be less than that of water containing indicators of human origin. Under these conditions, a realistic microbial standard for cistern water of 10 fecal coliforms/100 ml is proposed.
Groundwater recharge with Honouliuli wastewater irrigation: Ewa plain, Southern Oahu, Hawaii.
Lau, L. Stephen
Groundwater replenishment by irrigation with primary chlorinated effluent from the Honouliuli Wastewater Treatment Plant was tested in a three-year demonstration project for the Ewa limestone aquifer, island of Oahu, Hawaii. Among the six options tested with different combinations of crops (California grass and sugarcane), irrigation methods, and effluent application rates, the most acceptable was California grass which was grown in plots (0.5-acre each) surrounded by an earth berm and border-flood-irrigated intermittently at an average rate of 20 in./wk. Yield of 1 mgd recharge water required a 14.6-acre plot for this option. For all options, recharge through 3 feet of vegetated, fairly permeable soil overlying 30 feet of permeable reef limestone rock freshened groundwater chlorides to 245 mg/l, stripped virtually all effluent nitrogen, and inactivated effluent bacteria. Toxics analyzed (pesticides and heavy metals) were all below action or detectable levels. The natural system, which acts as a surface living filter and a subsurface trickling filter, outperformed secondary treatment in improving the water quality. No adverse environmental effects were identified-no surface runoff, no insects, and no groundwater contamination. Soil clogging was not evident. Plots were free of shallow standing water except for a few hours after effluent application. The mild odor noted only infrequently on site was less than that at the treatment plant. The biomass produced was of usable quality and adequate quantity. The simulated recharge water spread in the aquifer several hundred feet from the site after the irrigation phase of a California grass growth cycle. The state of Hawaii is presently planning a large-scale water reclamation facility that will upgrade the Honouliuli primary effluent by this system to a quality suitable for subsequent reuse.
Hawaii: A tropical paradise with clean water environment
Lau, L. Stephen
This paper discusses Hawaii in terms of a tropical paradise with a clean water environment. Water resources include groundwater, coastal waters, and other waters such as the few natural lakes and large perennial rivers, streams, rainwater caught by rooftop catchment systems, wastewater effluent (for reuse on land), and desalted water (using membrane technology). Water regulation and management, as well as research and graduate education, are discussed. The paper also includes lists of some outstanding successes and some lessons (learned and in progress) regarding Hawaii’s water resources and water environment.
On the numerical solutions of one-dimensional flow in the unsaturated zone.
El-Kadi, Aly I.
Analysis and prediction of water flow patterns in the unsaturated zone are critical to many water resources and environmental problems. Examples of such problems include infiltration, which is an important part of the hydrologic cycle encompassing the associated movement and storage of subsurface water. Soil properties are a major factor in controlling rainwater partition between infiltration and runoff as well as in controlling moisture movement. Hence, an accurate estimation of infiltration and the factors affecting it is required to facilitate a reliable prediction of runoff and subsurface moisture distribution. Another example is related to agricultural management in which unsaturated water flow needs to be considered in decision making regarding irrigation. Finally, chemical transport in the subsurface environment is greatly influenced, under certain conditions, by flow in the unsaturated zone. Contamination may be caused by leakage from sanitary landfills or by recharge of sewage water under unsaturated flow conditions. Irrigation and rainwater dissolve and carry fertilizers, pesticides, and other chemicals under unsaturated conditions also. In most cases, understanding chemical transport and transformations in the unsaturated zone is essential for assessing the actual or potential contamination of groundwater aquifers. Flow in the unsaturated zone is usually simulated by solving the Richards equation, which is derived by combining the mass conservation equation and Darcy’s law. Recent studies have reported problems in solving such an equation within a numerical framework. This paper reviews the theory and various conventional numerical solutions pertinent to the problem. It also covers recent advances in numerical techniques that are mostly aimed at improving the efficiency of the solutions by optimizing the size of the spatial and temporal increments. Most of the attempts are related, in general, to equation transformation, solution iteration, and interblock parameter estimation. However, there is still room for improvement, because in some cases accuracy may require the use of small increments, on the order of a few centimeters and seconds for the spatial and temporal increments, respectfully. Such a need is critical because of the burden involved in model applications for large-scale, multidimensional problems. Although only one-dimensional problems are addressed here, many of the issues involved can be readily extended to multidimensional cases.
Ground-water tracing with injected helium.
Gupta, S.K., L. Stephen Lau, and Philip S. Moravcik
Helium has several characteristics that make it attractive for use as a tracer in hydrological studies. Two types of experiments were conducted to investigate applicability of helium as a tracer of groundwater movement. The experiments included studies using laboratory sand and soil columns and field groundwater tracing in a basaltic aquifer. A water helium analyzer comprised of a thin quartz glass membrane and diode ion pump (making use of the preferential permeation of helium through the quartz glass into an evacuated space) was developed and used for the experiments. Study results demonstrated that breakthrough curves of specific conductance and helium were similar under saturated conditions. In the unsaturated sand/soil columns, breakthrough curves of helium were retarded relative to specific conductance, reducing the usefulness of helium as a tracer.
Use of helium as a hydrological tracer.
Gupta, Sushil K., Philip S. Moravcik, and L. Stephen Lau
Helium has several characteristics which make it attractive for use as a tracer in hydrological studies. These include its inert nature, relatively high solubility in water (~1%), low molecular diffusion in water, ready availability in commercial quantities, nontoxic nature, and low background atmospheric concentration. The use of helium as a tracer of water movement has become possible through the development of an instrument which takes advantage of the fact that at room temperature helium diffuses through a quartz glass membrane at a rate of three to four orders of magnitude greater than any other gas. This paper describes (1) a set of experiments undertaken to compare breakthrough of helium with common salt (NaCl) tracer through laboratory sand columns; (2) a set of groundwater tracing experiments conducted in a basaltic aquifer in central O’ahu, Hawai’i; and (3) two laboratory experiments undertaken to evaluate the applicability of helium instrumentation for the tracing of submerged plumes in open water conditions. The test results demonstrate that helium behaves as a conservative tracer during saturated flow through porous media. During unsaturated flow, exchange of helium with air entrained in the porous media reduces its usefulness. During submerged flow of a labeled plume, helium behaves like fluorescein in a relatively tranquil laboratory tank environment for hours but is gradually lost through the air-water interface, thus limiting the usefulness of helium in shallow plume tracing studies to short duration experiments.
Stochastic analysis of the relationships between saturated hydraulic conductivity variance and solute dispersion in heterogeneous soils
Azimi-Zonooz, Ali, and Clark C.K. Liu
The effect of three-dimensional heterogeneity of saturated hydraulic conductivity on the vertical transport of solutes in soils is examined by means of controlled numerical experiments. Saturated hydraulic conductivity, an important transport parameter that controls the dispersion of pollutants in heterogeneous soils, is assumed to be composed of a homogeneous mean value and a perturbation caused by the vertical variability of soil properties, producing a stochastic process in the mean flow direction. The spatial heterogeneity of porous soils is characterized by the variance and correlation scale of the saturated hydraulic conductivity in the transport domain. Numerical experiments are carried out to evaluate the extent of contaminant dispersion in Hawaiian Oxic soils when uncertainty exists as a result of the spatial heterogeneity of saturated hydraulic conductivity. Statistical analysis of the saturated hydraulic conductivity measurements on undisturbed soil cores from two locations in Hawaiian Oxic soils indicated two different soils with the same mean and different variances. The partial differential equations describing three-dimensional transient flow and solute transport in soils with a random conductivity field were solved to evaluate the effect of these two variance levels on the transport of a contaminant plume originating from the surface. The significance of the variance on the spatial and temporal distribution of tracer concentrations is demonstrated using solute breakthrough curves at various depths in the soil profile. The longitudinal macrodispersivity resulting from tracer spreading in the heterogeneous soils with a finite local dispersivity is also analyzed. The analysis shows a similar solute dispersion behavior for the two variances. However, there is an overall reduction in the dispersion of solutes resulting from a uniform velocity field with the same mean. Macrodispersivity values in heterogeneous soils are proportional to the variance at smaller travel distances but converge to the same value at larger travel distances.
Artificial recharge of ground water for all purposes?
Lau, L. Stephen
Along a dry, hot coast on the island of Oahu, Hawaii, several needs-water demand for a new city, salinization control for a limestone aquifer, and management of wastewater effluent from an ocean outfall discharge-can be met through artificial recharge of groundwater by irrigation with a primary effluent. Among the six options tested in a three-year demonstration project with different combinations of crops (California grass and sugarcane), irrigation methods, and effluent application rates, the most acceptable was California grass grown in 0.2-ha plots bordered by an earth berm and flood-irrigated intermittently at an average rate of 508 mm/wk. A yield of 0.044 m3/s recharge water required 5.9 ha of land for this option; an even higher yield was possible with a minor change in percolate quality. For all options, recharge through 0.9 m of vegetated, fairly permeable soil overlying 9.1 m of permeable reef limestone rock freshened groundwater chlorides to 245 mg/l, stripped virtually all of the effluent nitrogen, and inactivated effluent bacteria. Toxics analyzed (pesticide and heavy metals) were all below maximum contaminant levels. The natural system, which acts as a surface living filter and a subsurface trickling filter, outperformed the secondary treatment system in improving the water quality. No adverse environmental effects-surface runoff, insect infestation, and groundwater contamination-were identified. Soil clogging was not evident. Plots were free of standing water a few hours after effluent application. The mild odor noted only infrequently on site was less than that at the Honouliuli Wastewater Treatment Plant. The biomass produced was of usable quality and adequate quantity. The simulated plume by the recharge water spread in the aquifer several hundred feet from the site after the irrigation phase of a California grass growth cycle. This paper summarizes the technical results on which the planning of a large-scale facility can be based and addresses the institutional difficulties and land-use economics, both of which are immense obstacles yet to be overcome.
Use of a geographic information system in site-specific ground-water modeling
El-Kadi, A.I., A.A. Oloufa, A.A. Eltahan, and H.U. Malik
Groundwater modeling is hindered, in general, by the lack of adequate information about the groundwater system and hence the need for an interactive and efficient system for data preparation and results analysis. Such a lack of information usually necessitates by the use of a tedious iterative methodology within a sensitive analysis scheme. This study facilitates modeling efforts by using the data-handling and graphical capabilities of a geographic information system (GIS) in site-specific, numerical modeling of groundwater resources. Data for the island of Oahu, Hawaii, are given to illustrate the approach. The modeling procedure is integrated with the GIS as an item in the main menu. A USGS model, known as MOC, is linked into the system and applied to a case study to illustrate the procedure. The linkage is generic in nature and can be extended to other models as well. The availability of a programming language in the GIS package facilitates pre- and post-processing efforts within custom-made dialogue boxes and pull-down menus. On-line help screens for modeling as well as data handling can also be designed.
Wellhead protection strategy for small aquifers: A study of Hawaii.
Lau, L. Stephen, Delwyn S. Oki, and John F. Mink.
Small aquifers, especially those of high permeability and with well-defined boundaries, lend themselves to alternative approaches to wellhead and groundwater protection. This type of aquifer is common in Hawaii, and many occur elsewhere. Development of a wellhead protection strategy for Hawaii is technically difficult because of the wide range of aquifer types and groundwater extraction units. Three protection approaches are currently being considered for Hawaii. The first approach involves the delineation of wellhead protection areas around individual extraction units. This is the approach originally envisioned by the U.S. Environmental Protection Agency in its guidelines for delineation of wellhead protection areas. We have identified appropriate delineation methods for the principal extraction units in Hawaii. The second approach involves delineation of aquifer protection areas, which are based on aquifer boundaries. The aquifer protection area approach is conceptually superior to the wellhead protection area approach by virtue of its comprehensiveness since the entire aquifer is protected, rather than just isolated areas surrounding the wellheads. The third is a time-phased approach that involves the initial delineation of wellhead protection areas followed by an aquifer protection area; that is, delineate wellhead protection areas during the early stage of groundwater exploitation, and then switch to an aquifer protection area at a later stage of exploitation near the sustainable yield of the aquifer. These approaches provide a choice, depending on the degree of protection desired and the extent of groundwater development in the aquifer.
Modeling atoll groundwater systems.
Peterson, Frank L., and Stephen B. Gingerich
With the application of high-speed computer modeling, we have begun to understand the details of hydrodynamic processes within atoll groundwater systems. One model used to simulate variable-density groundwater systems within atolls is SUTRA. The use of this model to evaluate several aspects of fresh groundwater lens dynamics and development on atoll islands is described. Two different atoll models were simulated. The first uses a generic atoll island with hydrogeologic parameters that are a composite of several typical atoll islands in the Pacific Basin to evaluate controls on the size and dynamics of the freshwater lens. The second models development and sustainable yield under various recharge conditions for Roi-Namur Island in Kwajalein Atoll, Republic of the Marshall Islands.
Groundwater modeling in Hawaii: A historical perspective.
Lau, L. Stephen, and John F. Mink
Water supply has been a dominating feature in the evolution of the Hawaii economy since the first settlement of the islands more than a millennium ago. The early Hawaiians relied on water from streams, springs, and shallow excavations to irrigate crops, taro in particular. Water use was regulated by the Hawaiian chiefs and their land managers according to strict rules. The source and delivery systems were so well designed that they served the expanding economy for a century after the opening of the archipelago to the western world by Captain James Cook in 1778.
The prediscovery Hawaii economy was highly organized and successful. When Cook arrived the population of the islands was about 300,000, but a century later it had declined to about 60,000 as a result of devastation caused by western diseases and the breakdown of a unifying culture. The demand for water increased to meet the needs of new agricultural initiatives, especially sugarcane, exceeding the supply available from the intricate Hawaiian distribution network. Collection works and transmission systems were constructed by western entrepreneurs. By 1910 virtually every major surface water resource had been seized for plantation agriculture.
Still, not enough water was available to satisfy the thirst of the arid lands planted in sugarcane. The greatest impetus to the advancing agricultural economy came with the discovery of artesian groundwater in the Ewa Plain in southwestern Oahu in 1879. Widespread drilling followed, proving the existence of vast groundwater resources. The experience was quickly repeated on all of the major islands. The arid leeward plains of each island, blessed with a bounty of sunshine, became the premier agricultural lands through irrigation with groundwater. Honolulu, served by an unreliable surface water supply for all of the 19th century, prospered and grew after voluminous artesian groundwater resources were discovered beneath the coastal plain. The city became the uncontested urban and commercial center of the island chain.
Groundwater became the first choice for municipal drinking water, and as the public appreciated its purity and reliability it also worried about its sustainability. A severe drought in 1926 magnified the concern, leading to the creation of the City and County of Honolulu Board of Water Supply. Basic investigations by the U.S. Geological Survey, which had started a few years earlier, were expanded.
The adequacy of the groundwater resources of southern Oahu was severely tested in World War II when a large military population was grafted on the existing civilian and agricultural economy. Then in 1959 Hawaii became a state, setting off a wave of economic activity which concurrently expanded demand for water. By the 1970s the combined agricultural, military, and civil economy water demands in southern Oahu were rapidly approaching sustainability of the aquifers. Elsewhere in the islands economic expansion also strained water source and distribution systems. The adequacy of the groundwater supply persisted as an unusually widespread concern among the public. Finally, after nearly a decade of legislative attempts, a State Water Code regulating all water development became law in 1987.
Hydrogeology of the Marshall Islands
The Republic of the Marshall Islands consists of 33 atolls containing some 1,136 separate islands in the west central Pacific. The atolls are aligned in a NW-SE direction and extend over a distance of nearly 1,100 km. They form two roughly parallel chains, the eastern Ratak (sunrise) group and the western Ralik (sunset) group.
The indigenous people of the Marshall Islands are Micronesians. The first European contact was by Spanish explorer Alvaro Saavedra in 1529. However, the islands’ general lack of wealth and resources did not encourage exploitation until 1885, when Germany declared the Marshall Islands a protectorate. In 1914, Japan took control of the Marshall Islands and after 1919 administered them under a League of Nations mandate. During World War II, U.S. forces occupied the Marshall Islands after heavy fighting on Kwajalein and Enewetak, and in 1947 the Marshall Islands became a U.S. trust territory. Finally, in 1986, under a compact of free association, the Republic of the Marshall Islands became fully self-governing and took control of all its internal and foreign affairs. Today the principal economic activities are still subsistence farming and fishing, with increasing effort being directed toward development of a tourist industry.
Although the Republic encompasses nearly 500,000 km2 of ocean, the total exposed land area is only about 176 km2 (Mink, 1986). Individual atoll islands are seldom larger than a few square kilometers and average only a few meters in elevation. Owing to their very small size, the lack of freshwater, and the danger of overtopping by storm waves, few of the islands are inhabited. The majority of the population lives on four major atolls: Majuro, the capital; Kwajalein, a center of U.S. defense activity; Jaluit; and Arno. The only public water systems in the Marshall Islands exist on several large islands in these atolls. Elsewhere, individual households obtain water from rainfall catchments and shallow dug wells (Mink, 1986). Most of the hydrogeologic information that serves as the basis for this chapter, therefore, comes from investigations conducted on the major atolls. In addition, a considerable body of information, especially geologic information, is from investigations conducted on Bikini and Enewetak Atolls prior to and after nuclear weapons testing during the 1940s and 1950s (Arnow, 1954; Emery et al., 1954; Ladd and Schlanger, 1960; Ristvet et al., 1978; Schlanger, 1963; Tracey and Ladd, 1974) [see also Chaps. 21, 22].
Modelling chemical transport in topsoil with a gamma distribution function.
Liu, Clark C.K., Pengzhi Lin, and Amalia Firman.
In applying the linear systems theory to the mathematical simulation of chemical transport in topsoil, the impulse response function is used to describe the overall effects of hydrodynamic and kinetic mechanisms of the system. The general nature of the impulse response function of a soil transport system can be represented by a gamma distribution function. The multiple regression equations derived in this study can be used to correlate parameters of a gamma distribution function with basic soil and chemical properties. Techniques developed in this study are most suitable for assessing spatial variation of groundwater contamination potential in a large area.
Water pricing and cost data: Getting the right numbers.
Moncur, James E.T., and Yu-Si Fok.
The data presented indicate that a substantial increase in water rates is often justified by real economic costs that are often partially hidden by standard accounting practice. Such a rate hike would provide each individual water consumer with a continuing and pervasive incentive to adjust his water use. The resulting conservation would stretch conventional sources of supply and forestall for many years the eventual necessity of developing desalination or other truly expensive sources.
Tubeworms (Serpulidae, Polychaete) collected from sewage outfalls, coral reefs and deep waters off the Hawaiian islands, including a new Hydroides species.
Bailey-Brock, Julie H.
Quantitative benthic samples collected near sewage outfalls off Oahu contained two species of small, fragile serpulid tubeworms previously unknown from Hawaiian waters. One is a new species of Hydroides without an opercular funnel, the other is Josephella marenzelleri, a broadly distributed but easily overlooked serpulid. Retrieval of these species is attributed to the use of a van Veen grab and elutriation and sieving to separate the polychaetes from the sediment. Another unrecorded small serpulid species, Rhodopsis pusilla, was found growing on a hard foliaceous sponge, in a cave, on a shallow reef off the Kona coast of Hawaii. Lava rocks collected with a submersible off southeast Oahu (330 m depth) have yielded another little known serpulid species, Filogranula gracilis.
Soil: The environmental source of Escherichia coli and Enterococci in Hawaii’s streams.
Hardina, C.M., and R.S. Fujioka
The concentration and sources of Escherichia coli and enterococci in a typical stream in Hawaii were determined. The concentrations of these two sanitary indicator bacteria in Manoa Stream consistently exceeded the new U.S. Environmental Protection Agency recreational water standard in freshwater of 126 E. coli/100 ml or 33 enterococci/100 ml. Escherichia coli but not enterococci was shown to multiply in stream water samples. Soil samples obtained near the stream bank, 10 m from the stream bank, as well as from a grassy area on the university campus, were determined to be sources of both E. coli and enterococci. These indicator bacteria were recovered from the surface of the soil as well as from soil samples at depths down to 36 cm. Soil is considered the most likely source for the high concentrations of indicator bacteria naturally present in the freshwater streams of Hawaii.
The marine Tubificidae (Oligochaeta) of Hawaii
Erasmus, Christer, and Dale Davis
The taxonomy and biogeography of the marine Tubificidae of the Hawaiian islands are studied for the first time. Twenty-three species are reported from largely subtidal habitats at the islands of Oahu and Maui. Eleven species are new to science: Bathydrilus exilis, Phallodrilus ampullarius, P. aquilinus, P. distinctus, Coralliodrilus aequalis, Inanidrilus dutchae, Olavius parapellucidus, O. (Coralliodriloides) strigosus, O. (C.) mokapuensis, Limnodriloides hawaiiensis, and Tubificoides pulvereus. Taxonomic notes are given for most of the other species. At least four of the species recorded from Hawaii have a more or less circumtropical distribution, whereas six others appear to be members of the Indo-West Pacific fauna. Three of the Hawaiian species were previously known only from the Caribbean area, indicating that they may be present in the East Pacific as well.
Hawaii. In Ground Water in the Pacific Region. Natural Resources/Water Series No. 12
A description of the major Hawaiian islands is presented. Conditions of groundwater occurrence, groundwater resources, and groundwater development are discussed.
Urban storm water runoff in Hawaii
Young, Reginald H.F.
Urban storm water pollution in Hawaii has been the subject of serious study for only a very few years. The major impetus for such study has been the need to determine the impact of stormwater or streamflows on coastal water quality. Early studies conducted by the Water Resources Research Center in Hawaii are of limited utility, in large part because of the sparseness of accompanying flow data. These attempts include stream surveys and collection and analysis of street sweepings. More recently published studies include stream surveys where pollutant loading rates have been determined, street sweepings where contaminant loads per length of curbing have been calculated, and direct monitoring in storm sewers. Data to date indicate contaminant hazards exist for receiving waters due to suspended solids, heavy metals, and possibly bacterial pathogens. Further work is necessary to refine loading rates and contaminant levels, especially as related to land-use pathogens.