Anaerobic bottom waters and profundal Sediments in lakes are important sites of mercury methylation (MeHg). The principal objective of this project is to better understand how key environmental factors, especially dissolved oxygen (DO), would influence MeHg cycling in lake sediments and bottom waters. The central hypothesis is that DO penetration into profundal sediments controls MeHg cycling by: (1) repressing MeHg bioproduction and release from surficial sediments, and (2) inhibiting the release, and subsequent water column methylation, of organo-Hg complexes bound to metal oxides in surficial sediments. Effects of DO and macrofauna density on Hg cycling in profundal sediments will be investigated based on intact prohundal sediment-water samples to be obtained from South Twin Lake on the Colville Indian Reservation and laboratory samples to be collected in the laboratory chambers.
The proposed research and educational plans are tightly integrated both topically and geographically. The overarching theme of Hg cycling in lakes drives both an ambitions research program and a creative outreach program, with both programs focused on the Colville Indian Reservation in Eastern WA. The integrated programs will advance discovery related to Hg cycling in lakes while promoting learning by American Indian high school students, undergraduates and graduate students. Broadening participation of underrepresented groups is at the core of the project's educational plan. Outreach to American Indian students that shares the thrill of scientific discovery combined with targeted recruitment efforts will ultimately result in increased representation of American Indians in environmental engineering and science.
