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You searched for +publisher:"University of Colorado" +contributor:("Richard Smith"). Showing records 1 – 2 of 2 total matches.

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University of Colorado

1. Legg, Teresa Marie. An Ecological Approach to Geogenic Arsenic Contamination in Bangladesh.

Degree: PhD, Ecology & Evolutionary Biology, 2013, University of Colorado

Bacterial communities can exert significant influence on the biogeochemical cycling of groundwater arsenic (As). This has globally important implications since As in drinking water affects the health of over 100 million people worldwide, including in the Ganges-Brahmaputra Delta region of Bangladesh where geogenic arsenic in groundwater can reach concentrations of more than 10 times the World Health Organization's limit. The overall goal of this dissertation research was to examine the relative effects of sediment geochemistry versus DOM chemistry on the structure of bacterial communities across groundwater gradients in an aquifer affected by geogenic arsenic contamination in Araihazar, Bangladesh. To this end, I employed interdisciplinary methods including analytical chemistry, 16S rRNA gene sequencing to characterize the composition and diversity of bacterial communities, and fluorescence spectroscopy and PARAFAC modeling in order to describe the chemistry and source of DOM in high As aquifers. My results indicate that differences in sediment grain size and geochemistry between sites significantly influenced the structure of bacterial communities, and the relative abundances of Deltaproteobacteria and Chloroflexi. However, my research also revealed that the supply and chemistry of groundwater DOM might have a greater effect on the composition of bacterial communities in aquifer sediments than site-specific differences in sediment geochemistry. While higher DOM concentrations in incubation experiments corresponded to a greater proportion of Deltaproteobacteria, Chloroflexi comprised a greater proportion of bacterial communities in environmental samples. Also, this research provided evidence suggesting that Chloroflexi, Epsilonproteobacteria and Deltaproteobacteria may influence groundwater As cycling through the respiratory reduction of quinone moieties in the high As aquifer environment. The combination of fluorescence spectroscopy and PARAFAC modeling, and 16S rRNA gene pyrosequencing was useful in deciphering novel relationships between bacterial taxa and DOM chemistry in the environment. Future research on geogenic As contamination should investigate the metabolic activities of Deltaproteobacteria, Chloroflexi, Epsilonproteobacteria under environmental conditions in high As aquifer environments. Advisors/Committee Members: Diana Nemergut, Diane McKnight, Steve Schmidt, William Lewis, Richard Smith.

Subjects/Keywords: geochemistry; DOM chemistry; groundwater; Biochemistry; Ecology and Evolutionary Biology; Environmental Microbiology and Microbial Ecology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Legg, T. M. (2013). An Ecological Approach to Geogenic Arsenic Contamination in Bangladesh. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/ebio_gradetds/44

Chicago Manual of Style (16th Edition):

Legg, Teresa Marie. “An Ecological Approach to Geogenic Arsenic Contamination in Bangladesh.” 2013. Doctoral Dissertation, University of Colorado. Accessed December 13, 2019. http://scholar.colorado.edu/ebio_gradetds/44.

MLA Handbook (7th Edition):

Legg, Teresa Marie. “An Ecological Approach to Geogenic Arsenic Contamination in Bangladesh.” 2013. Web. 13 Dec 2019.

Vancouver:

Legg TM. An Ecological Approach to Geogenic Arsenic Contamination in Bangladesh. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2019 Dec 13]. Available from: http://scholar.colorado.edu/ebio_gradetds/44.

Council of Science Editors:

Legg TM. An Ecological Approach to Geogenic Arsenic Contamination in Bangladesh. [Doctoral Dissertation]. University of Colorado; 2013. Available from: http://scholar.colorado.edu/ebio_gradetds/44


University of Colorado

2. Yacob, Tesfayohanes W. Multiscale Investigation of Acid Mine Drainage: the Effect of Organic Carbon Cycling on Microbial Activity and Pyrite Oxidation.

Degree: PhD, 2012, University of Colorado

Acid mine drainage (AMD) generation from abandoned waste rock piles is a serious environmental problem. One proposed solution is the use of organic carbon to bring about biogeochemical changes that can slow down AMD. The growth of mine waste rock enrichments on a glucose substrate was studied in batch cultures and a monod kinetic model was developed. Various concentrations of soluble microbial products (SMPs) of these enrichments were studied for their interaction with ferric iron and the resulting effect on pyrite oxidation. Four Waste rock packed columns were run in series and the chemical and biological indicators of interest measured for the rock pore liquid and column bulk liquid effluent. The growth experiment results gave a maximum specific growth rate of 0.13 ± 0.01 (1/hr). The enrichments were able to grow from pH 1.6 to 6.0 and had a pH optimum between 2.5 and 3.0. A dissolved oxygen half saturation constant of 0.11 ± 0.05 mg/l was obtained indicating the high sensitivity of the organisms to oxygen. SMPs were able to reduce the pyrite oxidation rate by up to 90% with lysis derived SMPs having a much higher impact than growth derived SMPs for an equivalent SMP-DOC (dissolved organic carbon). A mathematical relationship was developed to predict the rate of pyrite oxidation given an SMP-DOC concentration. The column experiments showed that rock pores contain up to 16 times higher iron and sulfate concentrations compared to column bulk liquid effluents. These and other microbial evidence suggest high pyrite oxidation rate is maintained at rock pores and that bulk liquid effluent concentrations are controlled by diffusional exchange with rock pores as indicated by a tracer test. Results of the growth and SMP-ferric iron interaction study can be incorporated to AMD models and used to predict remediation effects of carbon addition. Waste rock AMD generation results can be used as preliminary guides to design efficient carbon delivery schemes to reactive sites of waste rock piles. Advisors/Committee Members: JoAnn Silverstein, Harihar Rajaram, Mark Hernandez, Diane McKnight, Richard Smith.

Subjects/Keywords: acid mine drainage; acidophilic heterotrophs; pyrite oxidation; rock pore; soluble microbial products; waste rock; Civil Engineering; Environmental Engineering; Environmental Sciences

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Yacob, T. W. (2012). Multiscale Investigation of Acid Mine Drainage: the Effect of Organic Carbon Cycling on Microbial Activity and Pyrite Oxidation. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/327

Chicago Manual of Style (16th Edition):

Yacob, Tesfayohanes W. “Multiscale Investigation of Acid Mine Drainage: the Effect of Organic Carbon Cycling on Microbial Activity and Pyrite Oxidation.” 2012. Doctoral Dissertation, University of Colorado. Accessed December 13, 2019. https://scholar.colorado.edu/cven_gradetds/327.

MLA Handbook (7th Edition):

Yacob, Tesfayohanes W. “Multiscale Investigation of Acid Mine Drainage: the Effect of Organic Carbon Cycling on Microbial Activity and Pyrite Oxidation.” 2012. Web. 13 Dec 2019.

Vancouver:

Yacob TW. Multiscale Investigation of Acid Mine Drainage: the Effect of Organic Carbon Cycling on Microbial Activity and Pyrite Oxidation. [Internet] [Doctoral dissertation]. University of Colorado; 2012. [cited 2019 Dec 13]. Available from: https://scholar.colorado.edu/cven_gradetds/327.

Council of Science Editors:

Yacob TW. Multiscale Investigation of Acid Mine Drainage: the Effect of Organic Carbon Cycling on Microbial Activity and Pyrite Oxidation. [Doctoral Dissertation]. University of Colorado; 2012. Available from: https://scholar.colorado.edu/cven_gradetds/327

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