Investigation of Increased Mercury Levels in the Fisheries of Lower East Fork Poplar Creek (LEFPC), Oak Ridge Reservation, Tennessee

The DOE Western Environmental Technology Office (WETO) is supporting remediation efforts on the U.S. Department of Energy Oak Ridge Reservation in Oak Ridge, Tennessee by performing this study. MSE Technology Applications, Inc. (MSE) has performed a series of literature reviews and bench-scale testing to further evaluate the mercury problem in the Lower East Fork Poplar Creek (LEFPC) at Oak Ridge. The primary problem is that total mercury (HgT) levels in LEFPC water decrease, while HgT levels in sunfish muscle tissue increase, with distance away from the National Security Complex (NSC), despite extensive source control efforts at the facility and within downstream riparian zones. Furthermore, dissolved methylmercury (d-MeHg) levels increase downstream from the NSC, especially during warm weather and/or high flow events. MSE performed four test series that focused on conversion of aqueous phase elemental mercury (Hg deg. A) to methyl mercury (MeHg) by algal-bacterial bio-films (periphyton) present in the stream-bed of LEFPC. Small (mg/L) quantities of un-sulphured molasses and peptone were added to some of the Hinds Creek samples to stimulate initial bacterial growth. Other Hinds Creek samples either were dosed with glutaraldehyde to preclude microbial growth, or were wrapped in aluminum foil to preclude Hg photochemical redox effects. Themore » bench-scale testing for Phase II was completed August 2006. The final reporting and the planning for Phase III testing are in progress. (authors)« less