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THE EFFECTS OF SEDIMENT CAPPING ON MERCURY METHYLATION
Impact/Purpose:
My proposed research will evaluate the effect of containment caps on mercury methylation processes in contaminated sediments. In-situ sediment caps are passive barriers that separate contaminated sediment from the overlying water and influence geochemical conditions in the underlying sediment. Mercury methylation occurs primarily in the bottom sediments of aquatic environments and the complex geochemical changes induced by cap placement will impact the mobility and fate of mercury.
The objective of this research is to evaluate the biogeochemical changes induced by cap placement and to examine how these changes will affect mercury methylation. In situ capping physically sequesters contaminated sediments from overlying water, reducing or eliminating the flux of organic matter and nutrients to the underlying sediment and driving the entire sediment layer anaerobic. In order to assess the effectiveness of containment capping strategies, the consequent effects on the complex processes controlling mercury methylation must be evaluated.
Description:
It is widely accepted that sulfate reducing bacteria are responsible for the bulk of mercury methylation in aquatic sediments. Consequently, it is expected that cap-induced changes to the extent and location of sulfate reduction will be directly related to changes in mercury methylation. The results of this research will provide practical information about the effects of capping on methylation processes which can be used to guide remediation efforts.