Publication Date

2016

Document Type

Thesis

Committee Members

Marjorie Markopoulos (Committee Member), Chad Hammerschmidt (Advisor), Silvia Newell (Committee Member)

Degree Name

Master of Science (MS)

Abstract

Mercury (Hg) is a toxic metal that, once converted to methylmercury by microorganisms, bioaccumulates in aquatic food webs and poses a health risk to wildlife and humans who eat fish. Wastewater treatment plants (WWTPs) are a source of Hg to surface waters, but little is known about the temporal variability of Hg concentrations in effluent and efflux to aquatic systems. I quantified the concentration of Hg in effluent from the City of Dayton (Ohio) and Ford Road (Xenia, Ohio) WWTPs and examined temporal variability over monthly and hourly time scales as well as efficiency of Hg removal. Over a 13-month sampling period, Hg concentrations in effluent averaged 0.73 ± 0.20 ng/L and 4.18 ± 1.45 ng/L for the Dayton and Xenia plants, respectively. Mercury concentrations in effluent from the Dayton plant did not differ among months, whereas effluent Hg concentrations from the Xenia WWTP decreased significantly over time, suggesting improved efficiency of Hg removal. Monthly averages of Hg concentrations in effluent varied by about a factor of two, similar to the hourly variability observed at the Xenia plant during a diurnal study. Both WWTPs removed ≥ 97% of Hg from wastewater and are estimated to contribute < 5% of the total Hg loadings in their receiving waters. Although the concentrations of Hg in effluent from the Dayton WWTP were consistent over the year, there was significant variation in effluent Hg concentrations from the Xenia WWTP. This emphasizes the importance of systematic sampling and not generalizing results to broader time spans or to other sampling sites.

Page Count

39

Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded

2016

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