Thesis (Ph. D.)--University of Wisconsin--Madison, 1956. / Typescript. Vita. Includes Effects of dietary arsanilic acid on chicks, by O.J. Abbott, H.R. Bird and W.W. Cravens, reprinted from Poultry science, vol. 33 (1954) p. 1245-1253. Includes bibliographical references (leaves 46-53).

Thesis (M.E.)--Worcester Polytechnic Institute. / Keywords: RRKM theory, transition state theory, selenium, kinetics, coal, arsenic. Includes bibliographical references (p.145-146).

No description available.

Thesis (M.S.)--Duquesne University, 2005. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 96-99) and index.

The properties of an element are highly dependent on its chemical form, it’s called elemental speciation. This study evaluates the arsenic species found in a range of food stuffs together with growing environments and toxicity issues. Total arsenic concentrations in fish tissue and vegetable crops were determined by ICP-MS following microwave-assisted acid digestion using nitric acid/hydrogen peroxide, trypsin and cellulase enzymatic extraction procedures. The extracted arsenic species were then quantified using HPLC-ICP-MS. A dilute nitric acid (1 % (v/v)) digestion procedure was also used to extract arsenic species from rice and the different parts (root, skin, stem, leaf and grain) of a range of plant crops. The study was extended to include the aqua-regia extractable arsenic content of the soils collected from the area where the plants had been cultivated in the Kurdistan region of Iraq. Irrigation water was also investigated, but found to contain low levels of arsenic. An anion-exchange HPLC-ICP-MS method was developed, using sulphate and phosphate, for the separation and quantification of AsB, MMA, DMA, InAsIII and InAsV. The results obtained for fish samples were in the range of 3.53-98.80 µg g-1 (dry weight) with non-toxic AsB being the predominant species. The InAsV concentration was in the range of 0.1-1.19 µg g-1 for all fish species except for the John Dory which was below the limit of detection (0.027 µg g-1). Total arsenic, arsenic species, and total multi-elements (including Ag, Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Si, Ti, V and Zn) were determined in rice samples from Kurdistan, Iraq and other regions of geographical origin. The transport of arsenic from the soil and irrigation water into roots, stem, leaf and subsequently into the grain or bean of the plants is important when assessing the potential health risks from food crops. For the soil sample, InAsV was found to be the major species with smaller quantities of InAsIII . After applying a full BCR sequential extraction procedure to the soils, it was found that 7.87 - 21.14 % of the total arsenic was present in an easily acid-soluble extractable form. Finally, a novel method was developed to measure total arsenic and arsenic species associated with vegetative DNA. In rice plant, it was found that InAsV incorporated within the DNA molecule in which it could replace phosphate. It was also found that the concentration of InAsV associated with DNA molecule decreased with decreasing total arsenic in the rice plant from the root to the leaf.

In this work, the optical properties of ZnO doped with arsenic and nitrogen were studied. The ZnO samples were grown by Metalorganic Chemical Vapor Deposition (MOCVD). The solubility of nitrogen in the ZnO films, as well as its activation upon annealing, was also investigated. Hydrogen is known as a major source for passivation of the acceptors in ZnO:N. Therefore, it is crucial to dissociate the complex(es) formed by nitrogen and hydrogen and diffuse out the hydrogen in order to prevent the reformation of such complexes. High temperatures (≥ 600 C) are required for these purposes. In order to effectively remove the hydrogen impurities from the sample, it is important to know the optical fingerprints of hydrogen and its thermal stability. Therefore, the effects of annealing and hydrogen plasma treatment on bulk ZnO (hydrothermally grown) were first studied. The use of bulk material for this purpose was motivated by the well-resolved photoluminescence (PL) lines observed for bulk ZnO, which allow the identification of the different lines related to hydrogen after plasma treatment. Annealing at 850 C was effective for the removal of most of the hydrogen related transitions in the near-band-edge emission. Also, additional transitions at ~3.364 eV and ~3.361 eV were observed after hydrogen plasma treatment, which were ascribed to hydrogen-Zn vacancy complexes. In this work, a comparative study of the annealing ambient and temperature on ZnO films grown on GaAs substrate, using diethyl zinc (DEZn) and tertiary butanol (TBOH), showed that arsenic diffuses in the ZnO films and gives a shallow level in the band gap, which is involved in an acceptor-bound exciton line at 3.35 eV. This shallow level is visible when annealing is performed in oxygen, but not when annealing is performed in nitrogen, and indeed only for annealing temperatures around 550 C. However, annealing in either ambient also causes zinc to diffuse from the ZnO films into the GaAs substrate, rendering the electrical properties deduced from Hall measurements ambiguous. For ZnO:N, NO was used as both oxygen and nitrogen sources. Monitoring the concentration of nitrogen, carbon and hydrogen in the ZnO films, the formation of different complexes from these impurities were deduced. Furthermore, an investigation of the effect of annealing on the concentrations of impurities showed that their out- diffusion was strongly dependent on the crystalline quality of the ZnO films. For porous ZnO films, obtained at low growth temperatures (≤310 C), the out-diffusion of impurities was efficient, whereas for films grown at higher temperatures, which have improved crystalline quality, the out-diffusion was practically nonexistent. The out-diffusion of unwanted impurities may activate the nitrogen dopant in the ZnO films, as was confirmed by the PL measurements on the different samples grown at different temperatures. PL transitions at ~3.24 eV and ~3.17 eV were related to substitutional NO. These transitions were more dominant in the spectra of samples grown at low temperatures. An additional transition at ~3.1 eV was assigned to a donor-acceptor pair transition involving VZn, instead of NO, as previously reported.

A. method for the synthesis of S³⁵-BAL has been described S³⁵-sulphate was reduced to the sulphide and converted to NaS³⁵H. The NaS³⁵H was then reacted with 2:3-dibromopropanol to form S³⁵-BAL. The product was characterized by sulphydryl content, preparation of two crystalline dithiolans, sulphur analysis and chromatographic behavior. The metabolism of S³⁵-BAL was studied in the Wistar rat. The isotopic BAL was administered by intraperitoneal injection and the S³⁵ content of the post-inject ion urine was studied. The maximum rate of S³⁵ excretion in the urine was observed in the first 6 hours after injection and was followed by a rapid decrease in S³⁵ excretion. This was true for both neutral S³⁵- sulphur and inorganic S³⁵-sulphate. The amount of neutral sulphur excreted in the urine also reached a maximum in the first 6 hours and returned to normal within 12 hours. The excretion of inorganic sulphate, however, remained abnormally high throughout the experiment. Approximately 4 - 19% of the excreted was S³⁵ in the form of inorganic sulphate while less than 0.5% was present in the ethereal sulphate. Six possible metabolic products were detected by radiochromatographic studies of the post-injection urine. These compounds were found to have the following Rf values when the chromatograms were run in a tertiary butanol-water solvent (70/35): Compound 1 0.07 - 0.10 Compound 2 0.25 - 0.30 Compound 3 0.45 - 0.50 Compound 4 0.60 - 0.65 Compound 5 0.78 - 0.85 Compound 6 0.95 - 0.98 Compound 1 was characterized as inorganic sulphate while compound 5 was found to be a thiol compound which arose following acid hydrolysis of compound 3. Extraction studies showed only compound 2 to be extracted with ether while all but compounds 1 were found to be soluble in n-butanol. Compound 4, the major metabolite, was shown to be only slightly soluble in n-butanol and insoluble in ether. No glucuronide of BAL or its metabolites have been found in the urine and no increase in glucuronic acid excretion was observed following BAL injection. The presence of a large amount of glucose in the post-injection urine was indicated by chromatographic studies. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

The contamination of groundwater by naturally occurring arsenic (As) in South and South East Asia has resulted in the exposure of an estimated 100 million people to hazardously high concentrations of this known carcinogen. Whilst the biogeochemical processes and mechanisms responsible for releasing As to groundwater are now understood, the fundamental controls on these processes have yet to be resolved. In particular, the role of different sources of organic matter (OM) in controlling the rate and extent of As release and how the contributions of these different sources may be influenced by groundwater abstraction practices, remains poorly constrained. Indeed, it is the absence of such key information which currently limits our capability to accurately predict both where and when As will be released in to the groundwaters of this region. Elucidation of the controls of these processes is therefore of vital importance for aiding policy makers and those responsible for mitigating the effects of the current catastrophe in providing a sustainable source of As free drinking water to millions of people in the countries impacted.We conducted investigations at two known As hotspots in West Bengal and Cambodia to assess the impact of groundwater abstraction practices on the composition of dissolved organic carbon (DOC) and As release. The radiocarbon age of DOC at both sites requires a contribution of young surface or near surface derived OM as well as contributions from older, sedimentary sourced OM. Mixing profiles at the Cambodian study site suggest this subsurface OM end member to have an age of between 1000 and 6000 years. A clear association is observed between high As concentrations in shallow groundwaters containing young DOC, with lower concentrations of As being associated with older DOC in deeper groundwater. This provides the first direct confirmation that younger, more labile sources of OM are able to support more extensive As release in these aquifers. Perhaps more importantly, it is shown that modern surface derived OM can be drawn into As contaminated groundwaters. Comparison of the residence times of groundwaters suggests that the extent of ground-surface water interaction is more extensive and extends to greater depths in aquifers that have been subjected to massive groundwater abstraction. Indeed, it is suggested thatgroundwater abstraction practices may be responsible for driving the downward transport of As contaminated shallow groundwater into deeper groundwater, and may potentially be driving changes in the composition of organic carbon within the groundwater. This could give rise to a more reactive, bioavailable organic carbon pool which has the potential to further influence As mobility in these groundwaters. The potential for secular changes in the groundwater As hazard in these regions must therefore consider the impact that changes in the DOC composition may have on the biogeochemical evolution of these aquifers.

Billions of people rely solely on groundwater for drinking and daily use. In the last few decades, groundwater was shown to be contaminated with arsenic in high concentrations, especially in Asian countries such as Bangladesh. Arsenic (As) is ranked the first among 20 toxic substances by the Agency for Toxic Substances and Disease Registry (ATSDR) and United States Environmental Protection Agency (USEPA). Because many diseases and deaths were linked to consumption of arsenic-contaminated groundwater, the world health organization (WHO) reduced the arsenic standard level for drinking water from 50 to 10 µg L-1. Urgent demands for safe drinking water lead to developing potential technologies for removal of arsenic from groundwater. Arsenic is mainly present as uncharged As(III) in groundwater, which makes it difficult to be efficiently removed by conventional treatment methods. Therefore, membrane technology could be a promising potential solution. Because membrane technology has not been widely tested for arsenic removal, a novel in-house defect-free interfacially-polymerized (IP) cross-linked polyamide thin-film composite (TFC) nanofiltration membrane, namely, PIP-KRO1, was tested in this research. Two commercial TFC membranes, namely Dow NF270 and Sepro RO4, were also tested and compared to PIP-KRO1. The membranes were tested at four different pH conditions (4, 6, 8, and 10) in a cross-flow flat sheet membrane unit. The experiments were divided into two parts: (i) the membranes were tested for water permeance and salt (NaCl) removal and (ii) tested for As(III) removal in the presence of 250 ppm NaCl. The results in this study showed strong size sieving rejection for RO4 and a combination of size sieving and charge exclusion mechanisms for PIP-KRO1 and NF270. In general, the rejection trend was RO4 > PIP-KRO1 > NF270 for both NaCl and As(III). In contrast, the trend for water permeance was NF270 > PIP-KRO1 > RO4. The minimum and maximum salt rejection at pH 4 and pH 10, respectively, were 85 and 98.8% for RO4, 57 and 89% for PIP-KRO1, and 34 and 76.8% for NF270. In addition, the TFC membranes demonstrated a maximum As(III) rejection of 98.7, 69.5, and 46.3% for RO4, PIP-KRO1, and NF270, respectively. Based on the characterizations of the membranes, PIP-KRO1 had the highest cross-linking (N/O ratio) followed by RO4 and NF270, respectively. The same trend was observed for the thickness of the polyamide selective layer (PIP-KRO1 > RO4 > NF270). The zeta potential for NF270 was slightly higher than that for PIP-KRO1; RO4 had much lower membrane surface charge. In terms of surface roughness, the following trend was observed: RO4 > PIP-KRO1 > NF270.

The legacy of monosodium methanearsenate (MSMA) application to golf courses is often arsenic concentrations above the EPA’s maximum contaminant level of 10 μg/L for drinking water and the FDEP soil cleanup target level of 2.1 mg/kg for residential areas. These concentrations pose a health risk and must be remediated for residential development. The objective of this study was to determine how arsenic concentrations vary spatially at a closed golf course poised for residential development. Groundwater and sediment arsenic concentrations were quantified and the controls on arsenic (As) mobility were characterized. The presence of nitrates and iron-(hydr)oxides at the studied golf course largely influenced putting greens having the least As in groundwater whereas roughs contained the most. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection