Dissertations and Theses of Interest

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    Hydraulic Parameter Estimation Using Aquifer Tests, Specific Capacity, Ocean Tides, and Wave Setup for Hawai'i Aquifers
    (Water Resources Research Center, University of Hawaii at Manoa, 2007-12) Rotzoll, Kolja
    The islands of Hawaii face increasing ground-water demands due to population growth in the last decades. Analytical and numerical models are essential tools for managing sustainable ground-water resources. The models require estimates of hydraulic properties, such as hydraulic conductivity and storage parameters. Four methods were evaluated to estimate hydraulic properties for basalts on the island of Maui. First, unconventional step-drawdown tests were evaluated. The results compare favorably with those from classical aquifer tests with a correlation of 0.81. Hydraulic conductivity is log-normally distributed and ranges from 1 to 2,500 m/d with a geometric mean of 276 m/d and a median of 370 m/d. The second approach developed a simplified parameter-estimation scheme through an empirical relationship between specific capacity and hydraulic parameters that utilized Hawaii's state well database. For Maui's basalts, the analysis yields a geometric-mean and median hydraulic conductivity of 423 and 493 m/d, respectively. Results from aquifer tests and specific-capacity relationships were used to generate island-wide hydraulic-conductivity maps using kriging. The maps are expected to be of great benefit in absence of site-specific field assessments. In the third approach, ocean-tide responses in the central Maui aquifer were used to estimate an effective hydraulic diffusivity of 2.3 x 10^7 m^2/d. The position of the study area necessitated refining the existing analytical solution that considers asynchronous and asymmetric tidal influence from two sides in an aquifer. Finally, measured ground-water responses to wave setup were used to estimate hydraulic parameters. Setup responses were significant as far as 5 km inland and dominated barometric-pressure effects during times of energetic swell events. The effective diffusivity estimated from setup was 2.3 x 10^7 m^2/d, matching that based on tides. Additionally, simple numerical ground-water flow models were developed to assess the accuracy of results from analytical solutions for step-drawdown tests, dual-tides and wave setup, and to evaluate sediment-damping effects on tidal propagation. The estimated mean hydraulic conductivities of the four methods range between 300 and 500 m/d for basalts in Maui. The results of different methods are consistent among each other and match previous estimates for basalts.
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    Fate and Transport of Selected Endocrine Disrupting Chemicals in Recycled Water Through a Tropical Soil
    (Water Resources Research Center, University of Hawaii at Manoa, 2006-08) Mohanty, Sanjay K.
    Endocrine disrupting chemicals (EDCs) are a group of synthetic and natural chemicals that have the potential to mimic the hormone-like activities in the human body. This study was conducted to recognize whether recycled water (a source of EDCs) has the potential to contaminate the environment when such water is used for irrigation purposes. Batch sorption and miscible displacement experiments were conducted to elucidate the fate and transport of four EDCs including estrone, 17β estradiol, octylphenol and nonylphenol in a soil from Hawaii. The sorption capacity of the soil from two depths (2 ft as topsoil and 15 ft as saprolite) was estimated using recycled water and deionized water as the mobile phases. The transport parameters of these contaminants were obtained by using the inverse modeling approaches as provided in the HYDRUS 1D code. All four EDCs sorbed significantly on the soil. Octylphenol and Nonylphenol rapidly degraded during sorption. The Freundlich model was suitable to describe the sorption isotherm. The sorption nonlinearity was relatively higher for saprolite compared to topsoil. Both physical and chemical non-equilibrium processes were found to affect the mobility of the EDCs in the soil. The migration of EDCs in the soil was enhanced in recycled water due to the presence of dissolved organic carbon and elevated salt concentration. The ambient pH had little effect on sorption of EDCs on the soil from either depth.
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    Assessing the Source of Fecal Contamination in Streams on Kaua'i Based on Concentration and Genotypes of FRNA Bacteriophages
    (Water Resources Research Center, University of Hawaii at Manoa, 2005-08) Vithanage, Gayatri
    Extensive data from O'ahu indicate that all streams on this island consistently exceed the USEPA standards (200 fecal coliform/100 ml, 33 enterococci/100 ml) for water quality. Soil was determined to be the source of the elevated counts of these bacteria. In tropical areas, as Hawai'i, these bacteria are able to survive and multiply in the soil. Thus, these bacteria can end up in nearby streams after heavy rains or due to erosion. As a result, the USEPA recommended indicator bacteria (fecal coliform, enterococci) cannot be used to reliably determine when waters in tropical areas are fecally contaminated. Several alternative indicators have been proposed for such areas such as C. perfringens and FRNA coliphages. Extensive monitoring data does not exist for the other islands of Hawai'i. Kaua'i differs from O'ahu in that it is older, wetter and contains an abundance of cesspools. The Nawiliwili Watershed, on the island of Kaua'i, was chosen for this study. Sampling was conducted over a period of one year, and all samples were assayed for the traditional USEPA indicators (fecal, coliform, enterococci) as well as two alternative indicators (C. perfringens, FRNA coliphages). Of the 14 sites sampled, 12 contained levels of fecal coliform and enterococci that exceeded the USEPA standards (200 fecal coliform/100 ml and 33 enterococci/100 ml. This is similar to what has been documented in O'ahu streams. Based on the concentrations of these indicator bacteria, the USEPA would deem these sites as sewage contaminated. However, monitoring of these same sites for C. perfringens indicated that there was no sewage contamination (geometric mean values fell below the proposed standard of 50 CFU/100 ml). FRNA coliphage data indicate that cesspools may be leaching into nearby streams. Two streams (Nawiliwili, Papakōlea) had geometric mean levels greater than the 50 PFU/100 ml (based on O'ahu streams). Other streams in the watershed may be sporadically contaminated by cesspool because elevated FRNA coliphage levels were detected on occasion. Genotyping these FRNA coliphage isolates furthered supported the theory that cesspools were contaminating these sites because 98% of the FRNA isolates were typed as human while only 2% were typed as of animal origin. Current USEPA standards (fecal coliform, enterococci) are not reliable indicators of sewage pollution in tropical areas, thus, alternative indicators such as C. perfringens and FRNA coliphages may prove to be better indicators in these areas.
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    Are Fecal Sterols a Possible Alternative Indicator of Human Waste Contamination in Hawaiian Recreational Waters?
    (Water Resources Research Center, University of Hawaii at Manoa, 2005-08) Brostrom, Kathleen A.
    Many of Hawaii’s recreational streams and beaches contain high fecal indicator bacteria levels that are not indicative of sewage pollution. Instead, this pollution is due to environmental sources of fecal bacteria which reside and multiply in tropical soils. Current EPA fecal indicator bacteria are no longer representative of human fecal contamination in tropical waters. Fecal sterols have been used as chemical indicators of fecal pollution in many parts of the world. The primary sterol found in human feces is coprostanol. Detection and quantification of coprostanol and related sterols using GCMS analysis provides a fingerprint that can be used to characterize fecal contamination. The objective of this study was to assay for fecal sterols as an independent method to determine whether streams in Hawaii are contaminated with sewage. This method was applied to ambient streams, a stream recently contaminated by a sewage spill, and a stream suspected to be affected by a sewage line leak. The results of this study showed that some ambient streams in Hawaii contain high levels of fecal indicator bacteria, but low concentrations of coprostanol (<10 ng/L). A stream contaminated with sewage during a sewage spill event contained high concentrations of coprostanol (18,000 ng/L) in the first 24 hours after contamination, but this level dropped to ≤ 60 mg/L after 72 hours. A stream suspected to be contaminated with sewage contained significant levels of coprostanol (>1000 ng/L) when fecal indicators were also high, confirming a possible sewage line leak. This study demonstrated that coprostanol is a useful and independent measurement of sewage pollution. It is best used in conjunction with other fecal indicators and human fecal markers if confirmation of human fecal pollution is sought.
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    Polyacrylamide (PAM) Effects on Viruses and Bacteria Transport in an Unsaturated Oxisol
    (Water Resources Research Center, University of Hawaii at Manoa, 2001-05) Wong, Tiow P.
    Experiments were to study the effects of anionic polyacrylamide (PAM) on viruses and bacteria movement in soil. A water pollution problem which affects all areas with significant rainfall is soil erosion and subsequent transport of soil and all land-based pollutants. In recent year, high molecular weight polymers, such as anionic polyacrylamides (PAMs), have been used for soil erosion control and subsequent environmental problems. PAM is found to enhance infiltration. Land application of manure, sludge, and wastewater is common in many areas of the world, including the United States. Bacteria, viruses and other pathogens can be found in these waste materials. Studies must be conducts to evaluate if the use of polymers will allow water pollution constituents such as chemicals, pesticides, and microbial pathogens to reach groundwater in aquifer.