Thesis advisor: Rudolph Hon / A groundwater plume beneath a capped landfill in north-central Massachusetts contains dissolved arsenic concentrations exceeding 10,000 ppb at several locations. The landfill closed in the early 1990's and contains minimally documented solid waste materials deposited over the course of nearly a century. The source(s), fate, and transport of arsenic in the landfill aquifer have been studied extensively over the past decade; however, the source and pathways of arsenic are not yet fully defined. The primary source of arsenic likely involves a combination of the landfill waste material, the peat, the underlying overburden sequence, and/or bedrock minerals. Arsenic mobilization is most likely assisted by reducing conditions created by the decomposition of organic materials within the landfill and underlying peat present prior to the initiation of waste disposal. Another possibility is an arsenic-bearing groundwater discharging from the underlying bedrock from the oxidation of naturally occurring sulfides. Aqueous arsenic species, including inorganic arsenite [As(III), As(OH)3] and arsenate [As(V), AsO(OH)3], and organic monomethylarsonic acid [MMA(V), CH3AsO(OH)2] and dimethylarsinic acid [DMA(V), (CH3)2AsO(OH)], provide information as to where the arsenic is primarily originating from and how it is transported through the aquifer. Furthermore, the analysis of major ions, metals, and groundwater parameters from different zones of the landfill with varying arsenic concentrations will aid in the delineation of probable arsenic sources, the mobilization processes, and arsenic transport modes within the aquifer. A more complete conceptual site model with respect to arsenic speciation and groundwater chemistry will lead to a better understanding of geochemical processes within and beneath the landfill waste pile and also assist with future remediation of the aquifer. Using arsenic speciation and groundwater chemistry data, it was determined that although all four potential arsenic sources likely contribute to the total arsenic concentrations, the overall contribution from the landfill material, peat layer, and bedrock is minimal relative to the iron-oxyhydroxides coated on the sands particles throughout the aquifer which acts as the primary arsenic source. Oxidation-reduction potential and dissolved oxygen are the controlling factors in relation to mobilization and transport of arsenic species from aquifer features and an understanding of these processes at the local level can be further applied to global-scale arsenic contamination. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

"The St. Marks River basin encompasses a large portion of Leon, Jefferson and Wakulla counties in northwest Florida, extending from near the Georgia-Florida border to the Gulf of Mexico. Geology and surface topography of the basin is controlled by sediments of Upper Eocene, Oligocene, Miocene, and Quaternary age. In the portion of the basin south of the Cody Scarp, the Middle and Upper Miocene sediments have been eroded and the surface elevations are much lower than the northern upland. The Florida Aquifer is the principal source of ground water for the St. Marks basin. The major producing zone of the aquifer is comprised of limestones of Upper Eocene to Lower Miocene age. Overlying younger sediments serve as confining units throughout the northern half of the basin. Hydrologically, the aquifer is more transmissive near the St. Marks River. Water levels are generally higher in the recharge area in the northern portion of the basin with flow paths generally towards the springs and discharge areas near the Gulf of Mexico. Recharge is predominantly from local rainfall although some ground water is being contributed from the adjacent basin to the north"--Abstract. / Typescript. / "December 1984." / "Submitted to the Department of Geology in partial fulfillment of the requirements for the degree of Master of Science." / Advisor: James B. Cowart, Professor Directing Thesis. / Includes bibliographical references (leaves 163-165).

Yuen Yuk-man. / Bibliography: leaves 117-120 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

"Characterizing the effects of subsurface wastewater effluent discharges remains as a significant challenge impacting both ground-water and surface water resources. Important aspects of this challenge relate to the quantification of the main processes affecting oxygen consumption within a wastewater plume and to the ability of representing these conditions over a range of scales. The goal of this research is to improve our understanding of the relevant processes affecting oxygen consumption and thus, controlling natural attenuation in wastewater contaminated aquifers, and also to characterize and quantify these processes through modeling approaches considering different scales. The analysis included consideration of restoration processes associated with a former sewage disposal discharge in Falmouth, MA. The discharge was removed in 1995, and the site has been experiencing natural restoration since removal. A small-scale natural gradient tracer test, completed 6 years after cessation of sewage disposal, was used in previous research to develop parameters to characterize aerobic respiration and nitrification processes, key oxygen consuming processes for this site. In addition, field monitoring by the United States Geological Survey has provided a series of concentration profiles at different locations along the flowpath associated with the contaminant source. For this research, predictions obtained with the existing model were used in conjunction with these concentration profiles to assess the sensitivity and applicability in the parameters from this small-scale test, as well as their pertinence to the larger scale restoration process. By evaluating the applicability of this model to different scales and the associated variability of key model parameters, the approach provided an improved characterization of the primary processes affecting oxygen consumption."

Digitized by Kansas Correctional Industries

This dissertation combines field data, laboratory experiments, and mathematic models to (1) predict the probability of groundwater arsenic (As) contamination caused by geogenic sources and processes in shallow aquifers of the Mississippi Delta in southern Louisiana, (2) study the role microbes play in controlling As mobilization from sediments to groundwaters, and (3) simulate As mobilization and transport caused by changing redox conditions and groundwater geochemistry along a flow path within the southeastern Chicot aquifer in southern Louisiana. A model based on surface hydrology, soil properties, geology, and sedimentary deposition environments predicts that the Holocene shallow aquifers in southern Louisiana are at high risk of As contamination. Sediment incubation and pore-water chemistry suggest that microbes play a key role in mobilizing As from sediments by reductive dissolution of As-bearing Fe(III) oxides/oxyhydroxides. Finally, groundwater samples were collected along a 10 km flow path in the southeastern Chicot aquifer to determine groundwater geochemical parameters and to simulate reactive transport of Fe and As species along the studied flow path. The model well captures the general trends of Fe(II) and As(III) concentrations along the studied flow path and the close correspondence between Fe(II) and As(III) of the both measured and model predicted As(III) and Fe(II) concentrations support the hypothesis that microbially mediated reductive dissolution of As-bearing Fe(III) oxides/oxyhydroxides is the primary mechanism causing As mobilization from sediments to the shallow reducing groundwaters of the Mississippi Delta in southern Louisiana. / 1 / NINGFANG YANG

The purpose of this research has been to evaluate the potential contamination impact of cemeteries on groundwater. A comprehensive study of the groundwaters in the unsaturated and saturated zones of nine Australian cemeteries has been made, with most sampling between October 1996 and August 1998. Periodic sampling from 83 wells or ponds yielded 305 complete samples which were tested for at least 38 inorganic and 5 bacterial analytes. Other, partially complete samples were used for metals and bacterial analyses. The soils of all sites were tested for a range of analytes that might reflect or affect the presence of human decomposition products. The within-cemetery sampling has allowed inorganic chemical characterisation of cemetery groundwaters to an amount of detail not previously attained. In the past 100 years there have been fewer than 12 sampling-based studies published on any of these matters. The forms of nitrogen feature most prominently, but three groupings of analytes are recognised as major contributors, including Na, Mg, Sr, Cl, SO4 and forms of P; these outcomes are similar in each hydrogeological zone. This study is unique in that it has a broad focus on the environmental impacts in respect of bacterial presence and transmission, heavy metals and nutrients, and has put these into the context of cemetery management and operational practices. Cemetery functions are best understood conceptually as a special kind of landfill but they are strongly influenced by the temporal and spatial variability of cemetery practices. Human decomposition mechanisms and products are considered in detail. This information was used to model the impacts for a large municipal cemetery over a twenty year time-frame. The previously unquantified relationship of cemetery proximity to drinking water wells has been determined and guiding principles for cemetery location and operation have been prepared including separation distances from watertables and specification of buffer zones in different hydrogeological settings. The related issue of the disposition of cremated remains is also considered and guidelines developed for scattering of these within buffer zones. The amounts of decomposition products leaving cemeteries are very small, and well sited and managed cemeteries have a low impact on the environment. Cemeteries should not be regarded as a detrimental landuse and the in-soil interment of human remains and re-use of graves are sustainable activities. However, almost all cemeteries have some potential for pollution. The most serious situation is the escape of pathogenic bacteria or viruses into the environment at large. The answer to the question as to ‘whether any one cemetery pollutes?’ depends on the location and operation of the site in adherence to the affecting parameters. The question can only be resolved by a comprehensive geoscientific investigation with a focus on the hydrogeological setting. Such assessment needs to consider the effects if the practices and/or usage patterns within the cemetery change, or if there are unaccounted changes in impacting natural phenomena like floods.

Thesis (doctoral)--University of Tartu, 2007. / Vita. Includes bibliographical references. Also available on the Internet.

Thesis (M.S. in biological and agricultural engineering)--Washington State University, December 2007. / Includes bibliographical references (p. 53-57).

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.