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ROLE OF HUMIC SUBSTANCES ON THE PHOTOCHEMICAL REDUCTION OF MERCURY
Citation:
Ravichandran, M., R Araujo, AND R G. Zepp. ROLE OF HUMIC SUBSTANCES ON THE PHOTOCHEMICAL REDUCTION OF MERCURY. Presented at 220th American Chemical Society National Meeting, Washington, DC, August 20-24, 2000.
Impact/Purpose:
To improve the scientific understanding of the linkage between fish methylmercury and ambient mercury in the environment.
To complete a model for transformation and bioaccumulation of mercury than can be linked with models for atmospheric deposition and hydrology to yield a multimedia integrated modeling system capable of quantifying regional exposure to mercury.
To apply state of the art modeling to assess ecosystem interactions with exposures to mercury for impacted aquatic ecosystems (e.g., wetlands, lakes, rivers, estuaries) including spatially distributed (GIS-based) modeling of watersheds, lakes and rivers.
Description:
Solutions containing mercury and fulvic acids (isolated from the Florida Everglades) were exposed to simulated sunlight from a 1000-W Xenon lamp. In the ensuing reaction, ionic mercury was reduced to elemental mercury, which was collected on a gold trap and measured on a cold vapor atomic fluorescence detector. The amount of reduced mercury increased linearly with time in the absence of organic matter, whereas the rate was log-linear in the presence of organic matter. After 60 minutes of irradiating a solution containing 100 ng/L Hg, 5 mg C/L fulvic acid, and pH 6, about 56% of mercury was reduced to elemental Hg, while only about 7.2% was reduced in the absence of organic matter. The amount of Hg reduced remained nearly constant under varying DOC concentrations (1-40 mg C/L), while elemental Hg production was limited by the total amount of Hg in solution.