This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In collaboration with upcoming monitoring efforts by the U.S. Environmental Protection Agency, we are interested in examining shifts in mercury speciation through lower-trophic levels (e.g., phytoplankton and zooplankton), which typically generate higher (sometimes by 3 to 4 orders of magnitude) bioaccumulation factors for mercury, to upper-trophic levels (e.g., large mouth bass). The upper trophic level game fish has been shown in other mercury-contaminated systems to generate mercury concentrations over an order of magnitude above the USEPA Water Quality Guideline for mercury (currently 0.3 ppm). Because the toxicity of mercury is dependent on its chemical speciation, understanding mercury associations on a molecular level is critical to the effective management of contaminant sources and loads as well as to the development of process-integrated water-quality models for mining-affected aquatic systems. This beam time will be used to assess the feasibility of Hg LIII-edge bulk-XAS measurements in large-mouth bass that has the highest levels of mercurty among different organisms at the study site.
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