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theses

Mercury (Hg) is a heavy liquid metal with high volatility. Elemental mercury can be transported around the globe and cause environmental and health problems. The primary anthropogenic sources of Hg in our atmosphere are from mining and burning fossil fuels. When Hg from the atmosphere gets deposited on the earth's surface, microorganisms biotransform it into methylmercury. Methylmercury (Me-Hg) is a potent neurotoxin and can bioaccumulate through aquatic food chains. A simulation model that can predict Me-Hg production by microorganisms could improve quantification and potentially aid in developing management strategies. Me-Hg production is carried out by anaerobic microorganisms and the production rate depends on the molecule bound to Hg. Hence working with Hg is challenging and measuring production rates is time consuming and requires the use of sophisticated equipment. Studies have shown that sulfate-reducing bacteria are major contributors in the production of Me-Hg. The sulfate-reducing microorganism Desulfovibrio desulfuricans ND 132 was used to study the rates of Me Hg when exposed to different Hg (II) concentrations. ND 132 is an organism with a hypothesized metabolic pathway for Hg methylation, and it was used to determine Hg methylation kinetics. Based on lab studies with pure cultures of ND 132, a flux balance, a mathematical approach for analyzing the flow of metabolites through a metabolic network, was developed. The resulting simulation model attempts to predict Hg methylation rates for pure culture samples and Me-Hg concentrations for environmental samples. This simplified simulation model could help with rapid quantification and hence faster management and remediation of harmful mercury emissions and depositions.

ETD_8425

M.S.

Includes bibliographical references

by Swetha Kumar Kasetty

doi:10.7282/T3QR5166

ETD graduate

The author owns the copyright to this work.