Mercury in water, sediment and biota in streams (in red) at Oak Ridge Reservation.
Mercury, a pervasive global pollutant, is a contaminant of concern on the Oak Ridge Reservation and at numerous other sites. Mercury in it's common methylated form (monomethyl mercury) bioaccumulates in the food web and is highly toxic to humans and other ecological receptors.
Mercury bioacummulation is a global concern.
Biogeochemical factors controlling methyl mercury production at DOE sites represents a serious knowledge gap. For example, data collected on the Oak Ridge Reservation show that decrease in Hg levels does not necessarily lead to decrease in aqueous methyl mercury or to its bioaccumulation in fish. This observation suggests that at the high Hg levels commonly present in highly contaminated source areas, either methyl mercury production is inhibited or demethylation significantly exceeds methylation.
ORNL is working to close the gaps in our knowledge regarding the biogeochemical transformations of mercury. Specifically we are conducting research to:
- Elucidate the rates, mechanisms and controls of abiotic and microbial processes affecting Hg speciation and transformation, and resolve how and what critical Hg precursors are produced and subsequently methylated at the sediment-water interface.
- Understand the fundamental subcellular mechanisms of Hg methylation and demethylation by obtaining information on structure and dynamics of biological macromolecules involved in acquisition, transport and transformation of major Hg species and methyl mercury.
Basic research needs: Elucidate Hg methylation processes at sediment-water interface and the controls on methyl mercury production.