Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiii, 104 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 70-73).

University, Diss., 2003--Stuttgart.

Universiẗat, Diss., 2002--Kiel.

The mobility of trace metals and radionuclides released into aquatic and terrestrial environments by mining, industrial processes, and municipal waste disposal practices is an area that deserves significant scientific, public health, and regulatory attention. Indirect microbial interaction offers one potential mechanism for immobilizing these contaminants. For example, many metals, such as uranium and chromium, are less soluble once bound as iron oxide precipitates, thus inhibiting the spread of soluble heavy metals and radionuclides within groundwater and halting them from contaminating additional areas. Microbial iron oxidation is known to contribute to the immobilization of heavy metals and radionuclides in contaminated sites. A safe, cost-effective decontamination method for these materials is the association of radionuclides with iron oxides formed via microbial pathways, thus precipitating them out of solution and providing a promising technique for in situ bioremediation. Nitrate-dependent iron-oxidizing bacteria have been shown to play an important role in the retention of soluble uranium by forming iron oxides that absorb onto soluble U(VI) particles, rendering them immobile as U(VI)-iron oxides. Dechloromonas aromatica strain RCB is a β-proteobacterium that has been cultured and extensively studied in our laboratory and is capable of reducing perchlorate and anaerobically oxidizing benzene, humic acids, and ferrous iron. In addition, a newly-isolated β-proteobacterium, Diaphorobacter sp. strain TPSY, is of interest due to its ability to anaerobically oxidize humic acids, uranium, and ferrous iron. Thus, these two strains have enormous bioremediative potential and are prime candidates for in situ bioremediation. Microarray analysis was used to identify genes induced under iron-oxidizing conditions and RNA dot blotting was used to confirm mRNA expression in D. aromatica. As a follow-up, RNA arbitrarily primed (RAP)-PCR, a method used to randomly reverse-transcribe RNA into cDNA, was also used to identify expression that might not have been observed in the microarray. Genes that were identified from both microarray and RAP-PCR experiments include several hypothetical proteins, lipoproteins, and transmembrane proteins located in major operons, as well as genes annotated as signal transduction enzymes, c-type cytochromes, and proteins involved in chemotaxis, flagellar, and pilus development. Suicide vectors were used to create deletion mutations targeting the genes of interest. Additionally, transposon mutagenesis was used in Diaphorobacter sp. TPSY to identify any potential iron-oxidizing mutants. Out of seven TPSY mutants deficient in iron oxidation, four were identified as genes that encode an inner membrane protein, a signal transduction protein, a putative lipoprotein downstream of a cytochrome c, and a regulatory DNA-binding protein. Mutants were confirmed for their inability to oxidize iron by measuring Fe(II) concentrations over time with a ferrozine assay. The identification of genes involved in microbial anaerobic nitrate-dependent iron oxidation will prove to be a valuable asset when designing and assessing bioremediative strategies.

Agricultural runoff is a major non-point source pollutant in the Midwest and has been documented as a significant contributor to nutrient loads in the Mississippi River and subsequent hypoxic conditions in the Gulf of Mexico. In an attempt to minimize eutrophication, researchers have been collaborating with farmers to improve best management practices targeting nutrient retention. Over the past four decades riparian buffers have proven effective in retaining nutrients and sediment from agricultural runoff. We hypothesize that the addition of biochar to vegetated buffers can further improve nutrient attenuation by enhancing nutrient adsorption and cycling soil physical, chemical, and biological properties. In June 2012, fifteen flumes were established adjacent to fifteen existing flumes that were installed in 2008 for a related study at Southern Illinois University's farms. Each flume was either vegetated and/or amended with one of ten treatments and replicated three times: 1) giant cane (Arundinaria gigantea (Walt.) Muhl) established in 2008; 2) Kentucky bluegrass (Poa pratensis L.); 3) orchardgrass (Dactylis glomerata L.); 4) giant cane and compost (i.e., horse manure and mushroom compost); 5) biochar (i.e., pine and oak feedstock pyrolyzed between 450 °C and 650 °C.); 6) biochar and giant cane; 7) biochar, giant cane, and compost; 8) corn; 9) volunteer herbaceous species; and 10) a non-amended, non-vegetated control. Soil samples were collected prior to the application of soil amendments and nutrients were assessed annually. Surface runoff samples were collected from significant rain events (i.e., precipitation > 2.5 cm) and analyzed for nutrient and sediment levels. Data indicate that various combinations of biochar, compost, and giant cane were successful at reducing the frequency of surface runoff events as well as reducing concentrations of NO3- and NH4+ in agricultural surface runoff. Concentrations of dissolved reactive phosphorus (DRP) were greatly reduced when biochar and giant cane were present in the buffer without the addition of compost. Total phosphorus (TP) concentrations were lowest for the established giant cane treatment. There were no significant differences in the concentrations of total suspended solids (TSS) among the various buffer treatments. Data from this study are promising for the incorporation of biochar, compost, and giant cane into vegetated buffers to reduce the concentration of nutrients in agricultural surface runoff.

Total alkalinity (TA) is an important parameter in determining the uptake capacity of anthropogenic CO2 by the ocean. So far, oceanic carbon cycle models do not accurately represent TA and its variations. A spectrophotometric method was developed to measure variations of TA during two JGOFS cruises to the Northeast Atlantic in the early summer of 1990 and 1991 and in Emiliania huxleyi batch cultures. Short-term precision averaged around ± 0.1 %. A discrepancy of < 0.5% with coulometric results was observed in Na2COa standards. In natural seawater photometric TA was lower than potentiometric and calculated (pCOl, TC02) TA by about 1 and 2%, respectively. Discrepancies varied with hydrographic and/ or biological regime. Possible reasons for methodological shortcomings were considered, but without certified TA standards for different sample types, it was not possible to make an absolute statement about the accuracy of the methods involved. Combining the cruise results, photometric TA ranged by 90 and 20 p.eq kgSW-l in the surface mixed layer (SML) and at sub-thermocline depths, respectively. Some horizontal variation in the SML was related to salinity, but most of it could be linked to coccolithophorid growth during a bloom in 1991. Associated small-scale changes in TA of up to 40 J.leq kgSW-t occurred over 40 km. Independent estimates of seasonal net production of PlC and its relation to that of particulate organic carbon (POC) were established. Based on preceding investigations, a seasonal and latitudinal sequence of changes in surface TA was proposed which was corroborated by the photometric results from this study. The culture experiments revealed reductions in photometric TA which were half of those expected from parallel changes in measured PlC and nitrate concentrations. Proposed explanations for this included methodological shortcomings of all three methods and increases in final TA due to algal sulphate uptake and/or organic acid release. As the main conclusion, further targeted intercomparisons of TA methods are needed to identify the causes for errors in various TA methods in samples covering realistic hydrographic and biological ranges.

Os aquÃferos sedimentares presentes na regiÃo sul do Cearà representam importantes recursos hÃdricos naturais para a populaÃÃo dessa regiÃo, devido as suas boas qualidades e grandes disponibilidades. No entanto, constituem em recursos frÃgeis, sendo susceptÃveis a processos de degradaÃÃo por aÃÃes antrÃpicas. O objetivo dessa pesquisa à aprofundar os conhecimentos sobre a hidrogeoquÃmica do aquÃfero mÃdio presente no municÃpio de Juazeiro do Norte e compreender a dinÃmica do transporte de contaminantes nitrogenados em torno na bacia do riacho dos Macacos. Para isso, o diagrama de Stiff e a anÃlise estatÃstica de agrupamento hierÃrquico foram aplicados em dados de monitoramento hidroquÃmico de 26 poÃos tubulares, totalizando 158 amostras coletadas entre os anos de 2010 e 2014, e dados de testes de bombeamento foram utilizados em simulaÃÃes de fluxo hÃdrico subterrÃneo para modelar-se o transporte de contaminantes em zona vadosa e saturada. Os diagramas de Stiff mostraram a classificaÃÃo das Ãguas quanto à presenÃa dos Ãons dominantes, onde a qualidade das Ãguas mostrou-se sensÃvel Ãs mudanÃas de perÃodos secos e chuvosos e as anÃlises de agrupamentos conseguiram diferenciar grupos de Ãguas com qualidade distintas. Um modelo de fluxo subterrÃneo foi gerado por meio do software Visual MODFLOW Classic, o qual devidamente calibrado e validado permitiu identificar as cargas hidrÃulicas no aquÃfero no ano de 2015 e traÃar a espessura da zona vadosa sujeita a permitir processos de transformaÃÃo biolÃgica de compostos nitrogenados por reaÃÃes de oxidaÃÃo. SimulaÃÃes do software PHREEQC interactive mostraram que a zona vadosa possibilita o aporte de concentraÃÃes significativas de nitrato ao aquÃfero, e que contribuiÃÃes de esgoto por fossas sÃpticas tambÃm sÃo importantes fontes de contaminaÃÃo das Ãguas subterrÃneas. CenÃrios de exploraÃÃo do aquÃfero foram simulados e mostraram que um aumento no lanÃamento de nitrato no aquÃfero pode deteriorar a qualidade da Ãgua da maioria dos poÃos a nÃveis que inviabilizem os seus usos. Por outro lado, uma reduÃÃo gradativa da carga contaminante pode garantir a recuperaÃÃo da qualidade das Ãguas em toda a bateria de poÃos em atà dez anos; enquanto um corte sÃbito de lanÃamentos de esgoto no canal de drenagem e no riacho dos Macacos promove sua reduÃÃo dos teores de nitrato a nÃveis aceitÃveis em atà dois anos em todo o aquÃfero. Palavras-chave: Juazeiro do Norte, MODFLOW, Nitrato, PHREEQC, Riacho dos Macacos / The sedimentary aquifers present in the south of Cearà hold important natural water resources for the population of this region, because of their good quality and great availability. However, they constitute fragile resources being susceptible to degradation processes by human action. The objective of this research is to deepen the knowledge of the hydrogeochemistry of the medium aquifer in Juazeiro do Norte and understand the dynamics of transport of nitrogenous contaminants in the Riacho dos Macacos watershed area. For this purpose, Stiff diagrams and statistical analysis of hierarchical clustering were applied in hydrochemical monitoring data of 26 wells, totaling 158 samples, collected between the years 2010 and 2014, and data from pumping tests were used in groundwater flow simulations for modeling the transport of contaminants in the vadose and saturated zones. Stiff diagrams showed the classification of waters according to the presence of the dominant ions, where water quality showed changes for dry and wet periods: cluster analysis was able to differentiate groups with different water quality. A groundwater flow model was generated using Visual MODFLOW Classic software, which, properly calibrated and validated, identified the hydraulic head in the aquifer in 2015 and map the thickness of the vadose zone where biological transformation processes of nitrogen compounds by oxidation reactions happen. PHREEQC interactive software simulations showed that the vadose zone allows the input of significant concentrations of nitrate to groundwater, and sewage from septic tanks is also an important source of groundwater contamination. Aquifer exploitation scenarios were simulated and showed that an increase in nitrate release into the aquifer can degrade the water quality of most wells reaching levels which impede their use. On the other hand, a gradual reduction of the contaminant load can ensure the recovery of water quality throughout the wellfield in about ten years; while a sudden cut of sewage release into the drainage channel and the Riacho dos Macacos creek promotes a reduction in nitrate concentration to acceptable levels within about two years throughout the aquifer

Este trabalho descreve o desenvolvimento de um método eletroanalítico para determinação sequencial de nitrito (NO2-) e nitrato (NO3-), utilizando como técnica, a voltametria de pulso diferencial. O método se baseia na redução eletroquímica dos íons nitrato sobre um ultramicroeletrodo de ouro modificado in situ com cádmio depositado em regime de subtensão, e na seqüência, a remoção da monocamada de cádmio e a oxidação eletroquímica dos íons nitritos sobre o ultramicroeletrodo não modificado. Os ensaios voltamétricos para determinação quantitativa de nitrato e nitrito foram realizados em solução de NaClO4 0,1 molL-1 + HClO4 1,0x 10-3 molL-1 (pH = 3,3) preparada com água ultrapura. Utilizando as condições experimentais e os parâmetros voltamétricos otimizados, foram construídas curvas analíticas para determinação de nitrito e nitrato separadamente e também para determinação sequencial dos dois analitos. Para a determinação do NO2-, foi observado uma relação linear entre a corrente de pico e a concentração desse íon dentro do intervalo de concentração de 1,0 x 10-5 molL-1 a 1,1 x 10-4 molL-1, com um limite de detecção igual a 1,151 &plusmn; 0,091 &micro;molL-1 e limite de quantificação igual a 3,838 &plusmn; 0,091 &micro;molL-1. Para a determinação do NO3-, também foi observado uma relação linear entre corrente de pico e concentração desse analito dentro do intervalo estudado, que foi de 2,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1. O limite de detecção encontrado foi 4,839 &plusmn; 0,275 &micro;molL-1 e o limite de quantificação 16,131 &plusmn; 0,275 &micro;molL-1. A determinação sequencial de nitrito e nitrato foi avaliada dentro do intervalo de concentração de 5,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1 para NO3- e 1,00 x 10-5 molL-1 a 4,50 x 10-5 para NO2-. Para ambos os casos, a relação entre corrente de pico versus concentração do analito foi linear. Para a determinação sequencial os limites de detecção são 16,177 &plusmn; 0,794 &micro;molL-1 para NO3- e 2,243 &plusmn; 0,179 &micro;molL-1 para NO2- e os limites de quantificação são 53,922 &plusmn; 0,794 &micro;molL-1 para o NO3- e 7,476 &plusmn; 0,179 &micro;molL-1 para o NO2-. Os limites de detecção, os limites de quantificação e demais parâmetros estatísticos apresentados nesse trabalho, foram obtidos a partir de cálculos baseados em procedimentos descritos em Miller e Miller68 e Silva69. / This work describes the development of an electroanalytical method for sequential determination of nitrite (NO2-) and nitrate (NO3-), using as a technique, differential pulse voltammetry. The method is based on the electrochemical reduction of nitrate ions on a gold ultramicroelectrode modified in situ by underpotential deposition of cadmium, and subsequently, the removal of cadmium monolayer and the electrochemical oxidation of nitrite on ultramicroelectrode unmodified. The voltammetric analysis for quantitative determination of nitrate and nitrite were carried out in NaClO4 0.1 molL-1 + HClO4 1.0 x 10-3 molL-1 (pH = 3.3) prepared with ultrapure water. Using the optimized experimental conditions and voltammetric parameters, analytical curves were constructed for determination of nitrite and nitrate separately and for sequential determination of the two analytes. The relationship between peak current and concentration of NO2- were found to be linear in the concentration range between 1.0 x 10-5 molL-1 and 1.1 x 10-4 molL-1, with a detection limit of 1.151 &plusmn; 0.091 &micro;molL-1 and quantification limit of 3.838 &plusmn; 0.091 &micro;molL-1. For determination of NO3- was also observed a linear relationship between peak current and concentration of analyte within the concentration range studied, which was from 2.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1. The detection limit was 4.839 &plusmn; 0.275 &micro;molL-1 and the quantification limit was 16.131 &plusmn; 0.275 &micro;molL-1. The sequential determination of nitrite and nitrate was assessed within concentration range from 5.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1 for NO3- and from 1.00 x 10-5 molL-1 to 4.50 x 10-5 for NO2-. In both cases, the relationship between peak current versus analyte concentration were found to be linear. The detection limits for sequential determination are 16.177 &plusmn; 0.794 &micro;molL-1 for NO3- and 2.243 &plusmn; 0.179 &micro;molL-1 for NO2- and the quantification limits are 53.922 &plusmn; 0.794 &micro;molL-1 for NO3- and 7.476 &plusmn; 0.179 &micro;molL-1 for NO2-. The detection and quantification limits and other statistical parameters presented in this work were obtained from calculations based on procedures described in Miller and Miller68 and Silva69.

Highly concentrated ammonium nitrate emulsions are extensively used as an explosive in the mining industry. The emulsion is made from a supercooled aqueous salt solution with various stabilisers and an organic hydrocarbon phase under vigorous stirring to room temperature. The resulting emulsion is thermodynamically unstable and tends to crystallise over time. This is not suitable for the transportation or pumping of the emulsion in its application. This study showed that the crystallisation process of highly concentrated ammonium nitrate emulsions can be influenced by varying the emulsion droplet size as well as the types and ratios of surfactants used during the preparation stage. The results showed that there were significant differences in the rheological properties of the freshly-prepared emulsion, based on both the emulsion droplet size, and the type of surfactant and ratio of surfactants used. A decrease of the emulsion droplet size resulted in the increase of the elastic character, which can be explained by more compact network organisation of droplets. In terms of the different surfactants, it was shown that the Pibsa-Imide stabilised emulsions resulted in an emulsion with the highest storage modulus over the entire strain amplitude regions as well as the highest shear stresses over the whole shear rate region. The study showed that the relatively slow emulsion crystallisation process can be studied by using powder X-ray diffraction (PXRD). The amount of amorphous and crystalline phases present in the sample can be effectively quantified by using the Partial Or No Known Crystal Structural (PONKCS) method which can model accurately the contributions of the amorphous halo. An external standard calibration method, which used a different amorphous material with the crystalline material to obtain a suitable calibration constant, was employed. The results showed that the method would quantify the amount of the fully crystallised emulsion to be between 80 and 90 percent, which was in agreement with the solid content added during sample preparation and confirmed by Thermal Gravimetric Analysis (TGA). The simultaneous TGA / DSC results were able to show the number of solid/solid peak transitions as well as the total moisture content to be around 20 percent by mass in various emulsion samples studied. The study was able to model the crystallisation by using the Avrami and Tobin kinetic relationships which are commonly used for the crystallisation processes of polymers. The Avrami relationship proved to be useful in describing the type of crystallisation that occurred. This was based on literature where the exponent parameter (n) which was between 1 and 4 would relate to different types of crystallisation models. The results of this study showed that the crystallisation process would change for the samples that had shown a longer crystallisation process. The results indicated that the samples prepared with the lower Pibsa-Urea ratio showed a more sporadic crystallisation process, whereas the samples with the higher ratio of Pibsa-Urea showed a more controlled crystallisation process. The study also considered the rheological properties of the fresh emulsion, which showed that droplet size also had an influence on the stress strain relationship of the emulsion droplets.

abstract: In the United States, two-thirds of adults are considered hypertensive orprehypertensive. In addition, chronic illness, such as hypertension, cardiovascular disease, and type II diabetes, results in $3.5 trillion in annual healthcare cost and is the primary cause of disability and death. As a result, many individuals seek cheaper and simpler alternatives to combat their conditions. In this exploratory analysis, a study assessing nitrate intake and its effects on vascular function in 39 young adult males was investigated for underlying metabolic variations through a liquid chromatography – mass spectrometry-based large-scale targeted metabolomics approach. A two-way repeated measures ANOVA was used, and 18 significant metabolites were discovered across the time, treatment, and time & treatment groups, including prostaglandin E2 (p<0.001), stearic acid (p=0.002), caprylic acid (p=0.016), pentadecanoic acid (p=0.027), and heptadecanoic acid (p=0.005). In addition, log-transformed principal component analysis and orthogonal partial least squares – discriminant analysis models demonstrated distinct separation among the treatment, control, and time variables. Moreover, pathway and enrichment analyses validated the effect of nitrate intake on the metabolite sets and its possible function in fatty acid oxidation. This better understanding of altered metabolic pathways may help explicate the benefits of nitrate on vascular function and reveal any unknown mechanisms of its supplementation. / Dissertation/Thesis / Masters Thesis Nutrition 2020