Selenium has aroused much interest in the last decade. It is an essential trace element for man and animals and has been found to be the cofactor in two enzyme systems. The first, glutathionine peroxidase, acts as an anti-oxidant by destroying peroxides which attack cellular membranes. The second, iodothyronine 5'-deiodinase, converts thyroxine to triiodothyronine with the release of iodine. Selenium is obtained in the diet from plant and animal products and the amount present is dependent largely on the Se content and the chemical species present in local soils. Soils low in Se can lead to deficiency problems to the grazing ruminants, and have necessitated the use of Se fertilisers or direct Se injection into the livestock. The disposal of sewage sludge onto agricultural land will increase as new EC legislation comes into force in 1998. This may alleviate Se deficiency in soils or result in toxicity problems. The aims of this project were firstly to develop and validate a method to accurately measure Se in plants, soils and sewage sludges, examine which soil fractions Se was associated with and finally to study the uptake of Se by plants grown on sewage sludge amended soils. The Se concentration in samples was determined using isotope dilution - mass spectrometry by gas chromatography - mass spectrometry (GC-MS). This was the first application of the determination of Se in environmental samples and the use of a benchtop GC-MS for those analyses. Samples were spiked with 76-Se isotope solution. Plants were digested using nitric acid and hydrogen peroxide initially on a heating block and latterly by microwave oven digestion techniques. Soils and sewage sludges were digested using nitric acid and hydrofluoric acid. Selenium in the digests was reduced to Se(IV) and derivatised to 5'-nitropiazselenol. Validation of the methodology was achieved by the use of certified reference materials which gave results within the certified range with a low standard deviation. The Se content of four different freely drained acid Scottish soils under grasslands was in the range 0.5-0.8 mg-1 air dried soil and three sewage sludge samples contained between 1.1 and 3.5 mg g-1 dry matter. The ability of the digestion techniques to release organically bound Se as selenomethionine and selenocysteine was found to be around 100% efficient and the use of a microwave oven increased the number of samples which could be processed. A sequential extraction procedure was used to determine the soil fractions with which Se was associated. The four soils and the sewage sludge examined were all found to have less than 5% of the total Se available for plant uptake. The uptake of Se by plants grown in soils to which Se had been added as sodium selenate or sodium selenate was studied using both stable and radio isotopes of Se. Results obtained showed that the uptake of Se by plants grown in soils treated with selenite could be related to the soil characteristics, with ferric oxide levels, clay levels and organic matter content being the important factors. The uptake of Se by plants in the soils treated with selenate were less obviously related to soil properties but pH and P levels both appear to be important factors. Good reproducibility was obtained in all cases. Plants grown on sewage sludge amended soils were not found to contain measurable amounts of Se.

Total mercury (Hg) concentration provides insufficient information to understand Hg behavior in Hg-contaminated soil systems and to seek potential remediation technologies, because the distribution, mobility, bioavailability, and toxicity of Hg are dependent on Hg forms present in soils. The phase association of Hg in soil is investigated to evaluate potential environmental risk through combination of total Hg determination, soil fractionation, and speciation analysis of Hg in a Hg-contaminated DOE site. Besides total Hg concentration analysis, sequential extraction procedures and thermal desorption techniques were employed to study Hg binding forms in soils in this study. Total mercury concentrations ranging from less than 100 ng/g to more than 30,000 ng/g were detected. The highest form of mercury present in the soil is organically-bound mercury, followed by elemental mercury, and mercury sulfide. Bioavailable and mobile mercury is minimal.

Harmful algal blooms caused by eutrophication from fertilizer runoff carrying excess nutrients such as phosphorus have plagued natural water systems for over a century devastating a wide range of ecosystem services such as drinking water supplies, aquatic habitats, aquaculture, and recreational activities. The dissolved oxygen content of water controls many functions of a natural water system and can influence the speciation and bioavailability of phosphorus, particularly at the sediment-water interface. The impact of phosphorus internal loading to a Central Florida lake was examined seasonally using phosphorus speciation data collected. Phosphorus speciation in lake sediment was primarily controlled by sediment type and organic carbon content. Correlations between iron and phosphorus within the sediment indicated that anaerobic respiration and iron reduction was a factor in phosphorus speciation suggesting that oxygen content in the overlying water column was a primary factor in controlling internal loading. To prevent the release of phosphorus from sediments, oxygenation at the sediment-water interface is vital. Collagen, whey protein concentrate, and a composite were fabricated by electrospraying into core-shell micromaterials for the encapsulation of calcium peroxide as an oxygen releasing compound and characterized by SEM, FTIR, UV-Vis, and fluorescence spectroscopy. The micromaterials were soluble in water and released oxygen as a function of time at neutral pH. The micromaterials were used to treat anoxic lake water and sediment spiked with phosphate adsorbed to goethite in order to determine the effects of oxygen on the release of iron-bound phosphorus into the overlying water through controls on reductive iron dissolution. Systems remained oxygenated for 75-100 hours before returning to anoxic conditions. Evidence of iron dissolution was observed, but the reason as to why was indeterminant. Results indicated that multiple mechanisms were controlling phosphorus speciation and that dissolved oxygen was but one factor affecting phosphorus cycling in the benthic sediments.

Polycyclic aromatic sulfur heterocycles (PASHs) are sulfur analogues of polycyclic aromatic hydrocarbons (PAHs) commonly found in environmental samples exposed to oil contamination. The determination of PASHs in complex samples is far more difficult than PAHs because of the sulfur atom in the heterocyclic ring, which increases the total number of possible isomeric compounds. Since their toxicological properties vary considerably from isomer to isomer, the unambiguous determination of specific isomers in environmental samples is crucial for ecotoxicological purposes and human safety. GC-MS has been the primary analytical technique for the determination of PASHs in environmental samples. Unfortunately, as the number of aromatic rings increases, the increasing number of possible isomers with similar retention times and nearly identical mass fragmentation patterns makes separation and identification difficult. Recent developments in our group have shown that the analysis of PASHs in complex environmental extracts is best accomplished with sample fractionation via normal phase liquid chromatography (NPLC) and subsequent analysis of NPLC fractions via GC-MS. Specific PASHs are then identified on the bases of NPLC retention times, GC retention times and mass spectra. The first part of this dissertation investigates the analytical potential of low-temperature photoluminescence spectroscopy for the analysis of phenanthrothiophenes with molecular mass – 234 Da in NPLC fractions. Excitation and emission spectra recorded from n-alkane solutions at 77K and 4.2K showed strong phosphorescence from all the studied isomers at cryogenic temperatures. The analytical figures of merit obtained under steady state (fluorescence) and time-resolved (phosphorescence) conditions provided limits of detection at the parts-per-billion (ng mL-1) concentration levels. Processing 77K and 4.2K phosphorescence data with parallel factor analysis showed to be a robust approach that requires no further separation of NPLC fractions. The second part of this dissertation studies the adsorption of PASHs on microplastics (MPs); i.e., plastic particulates with dimensions ranging from 0.1 to 5000 µm. Once released into aquatic environments, PASHs have the potential to bioaccumulate and cause toxic effects in aquatic organisms. Since MPs can be accidently ingested by biota, the adsorption of PASHs on the surface of MPs might be a credible route by which PASHs enter the marine food web. To the extent of our literature search, there are no reports on the interaction of PASHs with MPs.

The large volume of crude oil released into the Gulf of Mexico by the Deepwater Horizon (DWH) accident has raised considerable concerns over potential ecosystem impacts. The dispersion of harmful oil components into the ocean waters could pose long term risks to flora and fauna. Due to the complexity of oil contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). A classic example is the analysis of the sixteen polycyclic aromatic hydrocarbons included in the priority pollutants list of the U.S. Environmental Protection Agency (EPA-PAHs). This dissertation tackles a different aspect of environmental analysis as is focuses on the photoluminescence spectroscopy of polycyclic aromatic sulfur heterocycles (PASHs). Since considering the EPA-PAHs alone can lead to drastic underestimations of potential toxic effects of oil spills, a strong case can be made for including hetero-aromatic compounds in risk assessments of contaminated sites. PASHs exist in an even greater variety of chemical structures than PAHs and, because of the asymmetry imposed by the heteroatom, the number of PASHs isomers is usually large. The existence of numerous isomers of the same molecular weight increases the difficulty of separation and identification by chromatographic methods. This dissertation demonstrates the capability to differentiate individual PASHs isomers of MW 234 g mol-1 via vibrational spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2K) temperatures. Fluorescence and phosphorescence spectra are presented for isomer determination at the parts-per-billion (ng. mL-1) concentration levels. It is demonstrated that the relatively long phosphorescence decays of PASHs facilitate the time discrimination of strong fluorescence. interference from PAHs and methylated-PAHs often present in Normal-Phase HPLC fractions. The spectral and lifetime databases compiled in this dissertation have paved the road to explore the full dimensionality of photoluminescence spectroscopy.

Based on a Ph. D. Thesis--ETH Zürich, 1996. / Includes bibliographical references and index.

Thesis (M.Eng.). / Written for the Dept. of Chemical Engineering. Title from title page of PDF (viewed 2008/03/12). Includes bibliographical references.

Thesis, (M.S.)--Oregon Graduate Institute, 2000.

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Orientador: Mary Rosa Rodrigues De Marchi / Banca: Mario Sergio Galhiane / Banca: Sonia Claudia do Nascimento de Queiroz / Banca: Antônio Augusto Neves / Banca: Maria Eliana Lopes Ribeiro de Queiroz / Resumo: Esta tese apresenta o desenvolvimento e a validação de um procedimento analítico, que permite a quantificação simultânea de sete fitoestrógenos (alteradores endócrinos - AEs) em água de rio e água sub-superficial em uma área rural com grande produção de soja. Os compostos selecionados para este estudo foram (genistina - GENIS, daidzina - DAID, equol - EQ, daidzeína - DAI, a genisteína - GEN, formononetina - FOR e biochanina - A - BIO). Este método consiste na préconcentração de amostras de água (1 L) em cartuchos Strata X de 200 mg, seguido por análise de todos as AEs por cromatografia líquida de alta eficiência com detecção por ultra - violeta (CLAE-UV). Do ponto de vista analítico, estabeleceu-se um método simples e de confiabilidade conhecida (exatidão, precisão, seletividade e robustez) para análise de sete fitoestrógenos de soja em água de rio e subsuperficial. Os limites de detecção e quantificação do método validado foram de 3,5 ng L-1 e 10 ng L-1 respectivamente para todas as moléculas estudadas e em ambas as matrizes. O método foi aplicado a amostras de água da região de Dourados (MS). Foram coletadas 92 amostras de água de rio e 16 de água subsuperficial, em quatro campanhas de amostragem ao longo de 1 ano. GENIS e DAID não foram detectadas em nenhuma das amostras. GEN e FOR foram os fitoestrógenos mais detectados, estando presentes em 50 e 34% das amostras, respectivamente. As concentrações individuais de fitoestrógenos situaram-se entre 12 e 1957 ng L-1, sendo que as maiores concentrações foram obtidas para o EQ e GEN para amostras coletadas em meses chuvosos na região de estudo. Amostras de água do rio Dourados e de água sub-superficial foram testadas para o efeito de alteração endócrina com o ensaio de levedura recombinante (RYA). O ponto de coleta de água sub-superficial (afloramento do lençol freático) apresentou... (resumo completo, clicar acesso eletrônico abaixo) / Abstract: This thesis presents the development and validation of an analytical procedure that allows the simultaneous measurement of seven phytoestrogens (endocrine disrupters - EDs) in river water and water sub-surface in a rural area with large soybean production. The compounds selected for this study were (genistin - GENIS, daidzin - DAID, equol - EQ, daidzein - DAI, genistein - GEN, formononetin - FOR and biochanin - A - BIO). This method consists of preconcentration of water samples (1 L) on Strata X cartridges of 200 mg, followed by analysis of all EDs by high performance liquid chromatography with detection by ultra - violet (HPLC-UV). From the analytical point of view, it was established a simple and known for reliability (accuracy, precision, selectivity and robustness) for consideration of seven phytoestrogens in soy and river water sub-surface. The limits of detection and quantification of the validated method were 3.5 ng L-1 and 10 ng L-1 respectively for all the molecules studied on both matrices. The method was applied to water samples from the region of Dourados (MS). We collected 92 samples of river water and 16 sub-surface water in four sampling campaigns over 1 year. GENIS and DAID were not detected in any sample. The phytoestrogens FOR and GEN were detected in most cases, present in 50 and 34% of samples respectively. Individual concentrations of phytoestrogens were between 12 and 1957 ng L-1, and the highest concentrations were obtained EQ and GEN for samples collected in the rainy months in the study area. Samples of river water Dourados and sub-surface water were tested for the presence of endocrine changes with recombinant yeast assay (RYA). The point of collecting subsurface water (groundwater upwelling) showed high estrogenicity values of 0.35 and 0.50 ng L-1 equivalent of estradiol in the months of April and August 2009 respectively. Chemometric methods of analysis... (Complete abstract click electronic access below) / Doutor