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Chronic exposure to naturally occurring arsenic (As) in groundwater threatens the health of >150 million villagers in S/SE Asia. In Bangladesh, low As aquifers offer the best hope of reducing the exposure of 35-40 million remain exposed to elevated levels of As in drinking water (>10 μg/L). These low As aquifers could be affected, however, by massive pumping from shallow (<30 m) depths for growing rice and overexploitation of deeper aquifer for municipal water supply. The goal of this dissertation is to assess the impacts of groundwater pumping on the distribution in groundwater of dissolved As, reactive carbon, and redox-sensitive elements in anoxic aquifers of Bangladesh based on long-term hydrologic measurements, geochemical analyses, and numerical flow modeling. In the second chapter, changes in the well-water As concentrations within a 25 sq. km area over a 10+ year timespan are assessed on the basis of continuous time series for 18 monitoring wells, a set of 271 wells resampled three times, and a large dataset obtained from blanket surveys of several thousand wells in the region. The two larger data sets both show a 10% decline in the initial areal mean As of 100 μg/L. This decline can be explained by flushing of As in the shallow aquifer by low-As recharge water, evidently compensated to some extent by the desorption of sediment-bound As. The presence of a large exchangeable pool of As in the sediment therefore seems to buffer changes in the distribution of As in the face of large perturbation in groundwater flow, albeit not enough to prevent some trends indicated by the detailed time series. The third chapter provides a complementary perspective on groundwater-sediment interactions by quantifying the rates of adsorption and desorption of As with column experiments conducted in the field for two different types of sediments: grey reduced Holocene sands and orange oxidized Pleistocene sands. The data show that, contrary to widely held beliefs, retardation of As transport by adsorption is quite similar in Holocene and Pleistocene sediments, even if Holocene sands initially contain a much larger pool of easily mobilizable As. The field column experiments also showed significant changes in solid phase speciation that affected As retention within a timespan of only a few weeks. Detailed field observations and flow modeling in the fourth chapter examine how perturbed flow paths can draw either As or reactive carbon into a Pleistocene aquifer. A groundwater flow model, constrained by head measurements and isotopic tracer data shows that certain portions of the aquifer are becoming increasingly contaminated with As as a result of municipal pumping, but against a background of redox transformation in the aquifer that probably preceded this perturbation. Overall, the research conducted for this thesis shows that alteration of the hydrological system due to local and regional forcing is affecting the distribution of As in groundwater. These changes do not affect all wells yet and, if they do, the increase in As concentrations observed so far are gradual because of the buffering capacity of the sediment. Lowering exposure by targeting low As aquifer should therefore definitely continue in Bangladesh, with particular attention paid to regular monitoring using vulnerability criteria this research has helped to identify.

Arsenic is a prevalent contaminant at a large fraction of US Superfund sites. Therefore, establishing techniques for accelerating As remediation could benefit many contaminated sites. Remediation of As contaminated groundwater by conventional methods, i.e. pump and treat (P&T), can be impeded by slow desorption of As from Fe and Al (hydr)oxides in aquifer solids. Through experimentation at different physical scales (grain, bench, and field scale), the potential for chemical additions to increase As release from sediments and possibly accelerate P&T remediation is examined. The work described here focuses on As contamination and remediation at the Vineland Chemical Co. Superfund site in southern NJ. The site is extensively contaminated with As resulting from decades of poor chemical storage and disposal practices by the Vineland Chemical Co., which manufactured As-based biocides from 1949-1994. Despite significant intervention, including groundwater remediation by P&T and treatment of solids via soil washing, sufficient site clean up could require many decades with current technologies. Chemical amendments that either compete with As for sorption sites or dissolve Fe and Al (hydr)oxides can increase As mobility and potentially improve P&T remediation efficiency. Simple extrapolations from bench scale column experiments based on pore volumes suggest that treatment with 10 mM oxalic acid could lower the time necessary for clean up at the Vineland site from 600 years (with current techniques involving just groundwater) to potentially on the order of 4 years. Small scale (<1 mm2) X-ray fluorescence maps from columns performed within the synchrotron beamline showed As release during oxalic acid treatment that was consistent with the bulk column materials and suggested that microscale processes can be predictive of the larger system. Finally, during a 3-month pilot study at the Vineland site, oxalic acid was injected into a section of the aquifer via an injection manifold system that was designed and built for the experiment. Groundwater samples indicate that introduction of oxalic acid led to increased As release at a sampling well and pump and treat recovery well in the study area. Addition of oxalic acid shows promise for accelerating treatment of a highly contaminated site.

Millions of villagers in Bangladesh drink water which exceeds the Bangladesh arsenic (As) standard of 50 micrograms per liter. Exposure to elevated levels of inorganic As (As) is associated with cancers of the skin, bladder, and lung, developmental effects, cardiovascular disease, skin lesions, and decreased children's intellectual functioning. Arsenic mitigation typically involves an outsider coming into a village to test the well water for As. After the results of the As test are provided this person typically leaves the village without providing the resources to address health concerns or give advice on mitigation options. In this dissertation, in an effort to provide ongoing resources on the health implications of As and to reduce As exposure, we sought to evaluate community level intervention strategies that could be used for successful As mitigation in Bangladesh. In Singair, Bangladesh, we conducted a household drinking water survey of 6649 households. The results of our survey indicated that 80% of wells were untested for As. Furthermore, we demonstrated that testing all of these untested wells would increase the number of households that lived with fifty meters of an As safe drinking water source by nearly 2.5 fold. In a cluster based randomized control trial (RCT) of 1000 households, we evaluated the effectiveness of having community members, compared to outside representatives, disseminate As education and conduct water As (WAs) testing. In 10 villages, a community member disseminated As education and provided WAs testing. In a second set of 10 villages an outside representative performed these tasks. Overall, fifty three percent of respondents with unsafe wells at baseline switched after receiving the As education and WAs testing intervention. There was no significant association observed between the type of As tester and well switching (Odds ratio (OR) =0.77; 95% confidence interval (CI) (0.37-1.61)). At follow-up, the average UAs concentrations for those with unsafe wells at baseline who switched to safe wells significantly decreased. In both intervention groups a significant increase in knowledge of As was observed at follow-up compared to baseline. The unavailability of As-safe drinking water sources in some villages was the most substantial barrier to well switching identified. The Hach EZ As field test kit measurements conducted by the As testers were highly correlated with laboratory results. This finding indicates that the As testers were able to accurately measure the WAs concentration of wells. Furthermore in our pilot study, the performance of the Econo-Quick (EC) kit, a new field WAs testing kit, was comparable to that of the commonly used EZ kit and the Wagtech Arsenator kit. The EC kit has the advantage of a substantially shorter reaction time of only 12 minutes in comparison to the 40 minutes required by these other kits. Through this dissertation, we have demonstrated that As education and WAs testing programs can be used as an effective method to reduce As exposure and increase As awareness in many As affected areas of Bangladesh. Furthermore, our findings indicated that many households are using tubewells that are untested for As therefore demonstrating the urgent need for access to water As testing services.

Arsenic is a known carcinogen, but is persistent in the environment, remaining a popular pesticide. It represents a particular hazard to humans when it stays resident in shallow soils and groundwater. This study of contaminant hydrogeology examined conditions at a former golf course in Florida with known arsenic contamination, and included a detailed examination of existing assessment data for the study area, an experimental pumping test with groundwater sampling, examination of sediment cores, and a preliminary geophysical investigation. The primary purpose was to determine what the existing controls are on As mobility. The primary findings were that redox conditions did have an effect on As concentrations. Groundwater in the study area is generally reducing, but during the pumping test was generally oxidizing. No potential As sources were definitively identified, and the most likely source remains anthropogenic, but interactive conditions with Fe, Mn, NO3-N, and S remain nebulous. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

M.Sc. (Geology) / Most rural communities in developing countries rely on borehole water as their only source of water. Since borehole water comes from underground, it is often considered pure and clean, but this is frequently not the case. Groundwater contains certain amounts of trace elements that may become deleterious to human health. The objectives of this investigation were to assess the concentration levels of Potential Harmful Trace Elements (PHTEs) and their spatial distribution patterns in borehole water in the Greater Giyani area of Limpopo, South Africa, and the potential human health risks associated with this. The method of research comprised two phases: (I) In the first phase, I assessed the occurrence and distribution patterns of PHTEs in the boreholes of the Giyani area. A total of 29 water samples were collected from boreholes (including 15 community boreholes and 14 primary school boreholes) in the Greater Giyani area during the dry season (July/August 2012), and for comparison another 27 samples (including 15 community boreholes and 12 schools boreholes) from the same localities during the wet season (March 2013). The samples were analysed for the trace elements arsenic (As), cadmium (Cd), chromium (Cr), selenium (Se) and lead (Pb) using the Inductively Coupled Plasma Mass-Spectrometry (ICPMS) technique. In order to assess the groundwater quality, PHTEs concentrations were compared with the South African National Standard of Drinking water (SANS 241-1:2011). (II) In the second phase, I evaluated the geographic variation between PHTEs and associated human health effects. This involved acquisition of data on a total of 100 cancer cases recorded during the period 2011-2014 at Nkhensani Hospital. ArcGIS Spatial analyst tool was used to create thematic maps illustrating spatial distribution of clinical data and arsenic concentrations in boreholes.

The worldwide natural occurrence of high levels of arsenic (As) in groundwater and its deleterious effects on human health have inspired a great amount of related research in public health and geosciences internationally. With >100 million people in South and Southeast Asia exposed to >10 µg/L As in shallow groundwater that they use for drinking, the installation of deeper, low-As wells has emerged as a major strategy for lowering the exposure. As the magnitude of deep pumping continues to increase, this work focuses on the geochemical and hydrologic questions surrounding the vulnerability and sustainability of low-As aquifers in Bangladesh, the country most affected by As crisis. In an effort to better understand the residence time of groundwater in low-As aquifers at depth, radiocarbon (14C) and 13C in dissolved inorganic carbon, tritium (3H), stable isotopes of hydrogen (2H) and oxygen (18O), and noble gas concentrations were measured across a ~25 km2 area of Araihazar, ~30 km east of Dhaka. Groundwater from >120 m depth is shown to be ~10,000 years old and its isotopic signatures indicate that recharge occurred at the time of changing climate from the late Pleistocene to early Holocene, with little recharge occurring since. In contrast, the intermediate depth low-As aquifers (<120 m) have a heterogeneous distribution of groundwater chemistry and ages, and contain groundwater recharged <60 years ago in certain locations. In one such area surrounding a small village, the effects that subsurface clay layer distribution has on recharge patterns and redox status of the intermediate aquifer was investigated. The relevant hydrogeologic and geochemical processes that led to documented failures of a community well at the site were assessed using a combination of solid and water phase geochemistry with tritium-helium (3H/3He) dating, hydraulic head monitoring, and pumping tests. Organic matter seeping from a compressible clay layer, which is subject to a pumping-induced, downward hydraulic gradient, reduces iron oxides and helps release As in the grey, upper part of the intermediate aquifer. No recent recharge was detected by 3H measurements in the upper, grey sand layer, however a layer of orange sand beneath it contains groundwater that was recharged 10-60 years ago. This groundwater laterally bypasses the confining clay layer to recharge the middle of the aquifer and contains dissolved As levels of <10 µg/L. In this particular case, the pore water that leaches from clay layers contributes to As contamination, whereas the lateral recharge with shallow groundwater coincides with the low-As depth. Thus, clay layers may not always protect the low-As aquifers from As contamination, even if they can block direct vertical recharge with shallow groundwater enriched in As and organics. Finally, the adsorption of As to aquifer sediments, as a natural mechanism of the low-As aquifer defense against contamination, was assessed in the field via a column study. The column experiments were conducted by pumping shallow, high-As groundwater through freshly collected sediment cores to quantify the retardation of As transport through the aquifer. This study demonstrated an elegant method of assessing contaminant transport under nearly in situ conditions that resulted in sorption estimates similar to those made by field studies using more challenging methods or located at hard-to-find sites with convenient flow patterns. My work, therefore, contributed to a better understanding of low-As aquifers in Bangladesh from the perspectives of both the groundwater flow and water-sediment interactions on various scales, and it integrated methods that can be employed elsewhere to characterize aquifers and study contaminant transport.

This dissertation examines topics related to development, environment and health in developing countries using empirical methods. In the first chapter, I study how developing countries can increase enforcement to reduce subsidy leakage in public programs, by investing in the state capacity to target program beneficiaries. This chapter further attempts to understand how the formal sector and black market respond to a policy that reduces diversion of a subsidized commodity. I explore these questions using the case of a Unique ID-based direct fuel subsidy transfer policy in India. Second chapter focuses on the health and wealth trade off near mineral mining operations in developing countries. Using extensive data on mining, health outcomes and assets from 44 developing countries, this study quantifies the wealth gain and adverse health impact of mineral mining. With a number of empirical strategies, this study shows that, despite high wealth gains, how heavy metal mining significantly increases the level of anemia in women and stunting in children living near mines. In the third chapter, I estimate demand for a water quality diagnostic product -- arsenic testing, when it is offered at a price. I further look into various aspects related to selection, learning and households behavioral response to the information. This study is based on a field experiment in Bihar, India.

Background: In the country of Bangladesh, arsenic (As) exposure and high plasma homocysteine (hyperhomocysteinemia; HHcys) are widely prevalent. An estimated 35-77 million people in Bangladesh are exposed to As above the World Health Organization standard of 10 μg/L, while a cross-sectional study by our group estimated that 63% of men and 26% of women had HHcys. Both As exposure and HHcys are associated with adverse health outcomes. Arsenic exposure is an established cause of skin, lung, and bladder cancer, and cardiovascular disease, while HHcys is a strongly associated with increased risk for cardiovascular disease. Chronic kidney disease is emerging as an As-linked disease outcome. Potential mechanisms for adverse health effects induced by As (e.g. nephrotoxicity) include oxidative stress and inflammation. Inorganic As is metabolized through a series of methylation and reduction reactions which facilitate As excretion in urine; arsenite (AsIII), the primary form of As in Bangladesh drinking water, is converted to monomethylarsonic acid (MMAV), monomethylarsonous acid (MMAIII), and dimethylarsinic acid (DMAV). The methyl donor for these methylation reactions is S-adenosylmethionine (SAM). Because the availability of SAM is modulated by various nutritional parameters, nutritional interventions have the potential to enhance As methylation. Supplementation with folic acid (FA), which increases liver SAM, has been shown by our group to enhance As methylation and lower blood As in folate-deficient Bangladeshi adults. The endogenous synthesis of creatine from guanidinoacetate (GAA) consumes a large proportion of SAM, and creatine supplementation in the diet can downregulate endogenous creatine synthesis by inhibiting GAA production. In this way, creatine supplementation has the potential to spare SAM, enhance As methylation, and also lower homocysteine (Hcys), a by-product of SAM-dependent methylation. The potential for dietary creatine to enhance As methylation may explain the frequently observed associations of urinary creatinine with a decreased proportion of inorganic As in urine out of total urinary As (u%InAs), and an increased proportion of DMA in urine out of total urinary As (u%DMA) in epidemiological studies. Alternatively, it is possible that these associations are due to confounding by renal function, which could influence both As and creatinine excretion. Objectives: Our objectives were to determine (1) whether folic acid and creatine lower blood As in a mixed folate-deficient and replete population, (2) whether creatine lowers plasma total homocysteine (tHcys), (3) whether As exposure is associated with increased inflammation and decreased estimated glomerular filtration rate (eGFR), and whether these effects are greater in those with a more oxidized plasma glutathione redox potential (EhGSH), and (4) whether As metabolite proportions in urine and blood are associated with eGFR, and whether these associations may explain the relationship between As metabolite proportions and urinary creatinine. Methods: We addressed these objectives in five epidemiologic investigations of As-exposed Bangladeshi adults, employing data from a randomized placebo-controlled trial (the Folic Acid and Creatine Trial (FACT)) and two cross-sectional studies (the Nutritional Influences on Arsenic Toxicity (NIAT) study, and the Folate and Oxidative Stress (FOX) study). In the 24-week FACT study, participants were randomized to receive either placebo, 400 μg/day FA (FA400), 800 μg/day FA (FA800), 3 g/day creatine (Cr), or 3 g/day creatine + 400 μg/day FA (Cr+FA400). At week 12, half of the participants in the FA400 and FA800 groups were switched to placebo, while the other half continued their assigned supplements. Additionally, at week 12 participants in the Cr and Cr+FA400 groups were switched to placebo. In Chapter 4 (FACT), we examined whether FA400, FA800, Cr, or Cr+FA00 lowered blood As to a greater extent than placebo over the first 12 weeks of the trial, and whether a rebound in blood As occurred from week 12 to 24 related to cessation of FA supplementation. In Chapter 5 (FACT), we examined whether Cr or Cr+FA400 lowered plasma tHcys to a greater extent than placebo or FA400 alone, respectively, over the first 12 weeks of the trial. In Chapter 6 (NIAT), we examined the associations of water and urinary As with eGFR, and whether eGFR confounded the associations between urinary creatinine and the urinary %As metabolites; we also explored the associations of eGFR with the urinary %As metabolites. In Chapter 7 (FOX), we examined the associations of eGFR with the urinary and blood %As metabolites; we also examined whether the relationship between blood and urinary %As metabolites was decreased among those with reduced renal function. In Chapter 8 (FOX), we examined the associations of water, blood, and urinary As with markers of inflammation (C-reactive protein (CRP) and α-1 acid glycoprotein (AGP)), and eGFR, and investigated whether these associations were modified by the plasma EhGSH. Results: FA800 lowered blood As to a significantly greater extent than placebo over the 24 weeks of the FACT study, with no rebound in blood As related to cessation of FA supplementation. FA400, Cr, and Cr+FA400 did not lower blood As to a greater extent than placebo (Chapter 4). Cr and Cr+FA400 did not lower plasma tHcys to a greater extent than placebo or FA400 alone, respectively. However, in the Cr+FA400 group we observed a significant correlation between a decrease in plasma GAA over time and a decrease in plasma tHcys over time (Chapter 5). Total urinary As was marginally associated with a decrease in eGFR in the NIAT study, though water As was not. Additionally in the NIAT study, while eGFR did not confound the relationship between urinary creatinine and urinary %As metabolites, we observed a positive association between eGFR and u%InAs, and a negative association between eGFR and u%DMA (Chapter 6). Likewise in the FOX study, eGFR was positively associated with u%InAs and negatively associated with u%DMA; the associations of eGFR with the blood %As metabolites were in the same direction, although not statistically significant. We additionally observed that for a given increase in blood %InAs, the increase in urinary %InAs tended to be smaller in those with reduced renal function, compared to those with normal renal function (Chaper 7). In the FOX study we also observed the total blood As and urinary As were marginally associated with decreased eGFR, while water As was not. Water As, urinary As, and blood As were significantly positively associated with plasma CRP in those with low plasma GSH or a more oxidized plasma EhGSH (Chapter 8). Conclusions: Strategies to reduce risk for As-induced diseases are sorely needed, particularly due to barriers to As exposure removal and/or persistent elevated risk from past As exposure. Several susceptibility factors which can potentially be intervened upon have been discussed in this dissertation, namely folate nutritional status, redox status, and renal capacity to excrete As. Our finding that folic acid supplementation (800 μg/day) lowered blood As to a greater extent than placebo in a randomized trial indicates that improving the folate status of the general Bangladeshi population may reduce the body burden of As. Folate fortification of food in Bangladesh, in addition to potentially reducing risk for As-induced diseases, would have the additional benefit of substantially lowering the prevalence of HHcys. Our finding in a cross-sectional study that individuals with a more oxidized plasma glutathione redox potential were susceptible to As-induced inflammation may indicate that improving redox status can protect against As-induced inflammation. Randomized trials are needed to confirm a protective effect of antioxidants; upon confirmation, antioxidant dietary recommendations for As-exposed populations could potentially be implemented. Finally, our cross-sectional finding of a positive association between eGFR and urinary %InAs, and that eGFR modified the relationship between blood and urinary %InAs, suggests that InAs excretion may be impaired among individuals with reduced renal function. A decreased renal capacity to excrete InAs may lead to accumulation of InAs in tissues, and related health effects. Potential interventions related to renal function include treatment of risk factors for chronic kidney disease (e.g. blood pressure, blood glucose) in order to prevent onset of renal function deterioration, or to screen for chronic kidney disease in order to identify susceptible individuals and conduct directed interventions. Of these three susceptibility factors, the strongest evidence exists for the potential of folic acid to lower blood As. In Bangladesh, where As exposure and HHcys are widely prevalent, folate fortification should be considered a viable option for reducing risk for As- and Hcys-related diseases.