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Contributed Papers |
Note that this page is constantly under revision, and the more recent abstracts are not online yet. Some of the more recent articles are still in preparation and have not yet been published. | back to publications main page |
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.
Abstract coming soon.
in preparation - not yet available - do not cite
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 hydrolgy.
Fares, A., and A. I. El-Kadi.
Abstract coming soon.
in preparation - not yet available - do not cite
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.
Abstract coming soon.
in preparation - not yet available - do not cite
Use of dissolved helium as an environmental water tracer.
Ritcher, F., and A. I. El-Kadi.
Abstract coming soon.
Analysis of an unconfined aquifer subject to asynchronous dual-tide propagation.
Rotzoll, Kolja, Aly I. El-Kadi, and Stephen B. Gingerich.
Abstract coming soon.
Analysis of an unconfined aquifer subject to asynchronous dual-tide propagation
Rotzoll, Kolja, 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.
in preparation - not yet available - do not cite
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 stepdrawdown 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.
in preparation - not yet available - do not cite
Micro-genetic algorithms and artificial neural networks to assess minimum data requirements for prediction of pesticide concentrations in shallow groundwater on regional scale
Sahoo, Goloka B., and Chittaranjan Ray.
in preparation - not yet available - do not cite
Flow forecasting using artificial neural network and a distributed hydrological model, MIKE SHE
Sahoo, Goloka B., and Chittaranjan Ray.
in preparation - not yet available - do not cite
Optimization of artificial neural networks using genetic algorithms
Sahoo, Goloka B., and Chittaranjan Ray.
in preparation - not yet available - do not cite
Effect of recycled water on transport of estrone and 178 estradiol in a tropical soil
Mohanty, Sanjay K., and Chittaranjan Ray.
in preparation - not yet available - do not cite
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.
in preparation - not yet available - do not cite
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.
in preparation - not yet available - do not cite
Monitoring strategy using FRNA coliphages and Clostridium perfringens to detect sewage contamination of recreational waters by subsurface cesspool discharges and surface sewage spill
Vithanage, G., G. Ueunten, and R. Fujioka.
Conclusions on the microbial quality of environmental waters in the state of
Hawaii are based primarily on data collected on the most urbanized and populated
island of Oahu and applied to the other six islands in the state. The objective
of this study was to assess the reliability of monitoring environmental waters
on the Hawaiian Island of Kauai for FIB or faecal indicator bacteria (faecal
coliforms, enterococci) as well as for alternative faecal indicators (C.
perfringens, F+ coliphages). The island of Kauai differs from Oahu in being
less urbanized, having higher rainfall and where sewage is primarily treated
by on-site cesspools. The monitoring data from this study confirmed data obtained
on Oahu that under ambient conditions, faecal coliforms and enterococci are
naturally present in high concentrations in soil, that soil rather than sewage
is the primary source for the high concentrations in all streams and therefore
FIB are unreliable indicators of sewage contamination. This study resulted in
new findings that monitoring for F+ coliphages but not C. perfringens
can detect stream contamination by subsurface cesspool wastes. Moreover, by
identifying and genotyping FRNA coliphages, additional evidence was obtained
to show that cesspool wastes are contaminating streams on Kauai.
in preparation - not yet available - do not cite
Distribution of discharge intensity along collector well laterals in a model of riverbed filtration
Kim, Seung-Hyun, Kyu-Hong Ahn, and Chittaranjan Ray.
ABSTRACT
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.
in preparation - not yet available - do not cite
Analytical groundwater modeling for estimating sustainable yield of lao Aquifer, Maui, Hawaii.
Liu, C. C. K., and X. Li. 2007.
in preparation - not yet available - do not cite
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 Mãnoa 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 Mãnoa Watershed) that contains the university campus.
Use of dissolved helium as an environmental open-water tracer.
Richter, Florian, Robert B. Whittier, and Aly I. El-Kadi. 2006.
in preparation - not yet available - do not cite
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.
Analytical groundwater modeling for estimating sustainable yield of a basal freshwater lens.
Liu, Clark C. K., John F. Mink, and John Dai.
in preparation - not yet available - do not cite
Restoration and protection plan for the Nawiliwili Watershed, Kauai, Hawaii, USA.
El-Kadi, Aly I., Monica Mira, James E. T. Moncur, and Roger S. Fujioka.
in preparation - not yet available - do not cite
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.
in preparation - not yet available - do not cite
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. in preparation - not yet available - do not citeDetermination 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
Liu, C.C.K., W. Xia, J.W. Park
A wind-driven reverse osmosis system for aquaculture wastewater treatment, developed at the University of Hawaii at Manoa, was tested at the experimental facilities on Coconut Island, Oahu, Hawaii. With this technology, a fish tank becomes a closed aquaculture production system with zero waste discharge. The permeate (freshwater) from the system can be used as the freshwater supply for fish culture, while the brine (concentrated wastewater) can be further processed into fish feed by a duckweed-covered reactor.Use of neural network to predict flash flood and attendant water qualities of a mountainous stream on Oahu, Hawaii
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.Unconfined Groundwater
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/eowWater 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.
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
No AbstractPrediction of permeate flux decline in crossflow membrane filtration of colloidal suspension: A radial basis funcion neural network approach
Chen, Huaiqu, and Albert S. Kim
No AbstractUse 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.
Progoniada 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
No AbstractValidity 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.
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.
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
Ray, Chittaranjan
Riverbank filtration (RBF) offers several advantages over the direct use of surface water. A number of dissolved and suspended contaminants of surface water—including pathogens and microscopic particles—are removed during passage of surface water through the river sediment–aquifer 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.
Male-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 O‘ahu, Hawai‘i
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 im¬portant source of organic enrichment in nutrient-poor sandy sediments within oligotrophic tropical waters. Five polychaete species, however, appeared partic¬ularly 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 pres¬ent 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 sed¬iment 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 sedi¬ments. 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 sen¬sitive to the community differences present near the outfall. The ZID commu¬nity 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 ob¬servation 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 mod¬erate 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 desig¬nated 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 wa¬ters 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 rec¬reational 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
Fujioka, R.S.
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.
Wastewater reuse
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 characteris¬tics 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. coliand 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 concen¬trations 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, O‘ahu, Hawai‘i
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