MONITORING MANOOMIN (WILD RICE) USING GEOCHEMICAL ANALYSES AT BIG RICE LAKE, MINNESOTA

Manoomin (Ojibwe for wild rice) is a culturally significant plant for Native American communities in the Great Lakes Region. Manoomin is threatened by anthropogenic activities such as mining. Tribal resource managers and University of Minnesota researchers are collaborating to restore manoomin populations at historically robust ricing lakes, including Big Rice Lake (BRL) in northeast Minnesota. Despite ideal hydrological conditions, manoomin has been sparse, possibly due to the presence of sulfide, which has been found to be toxic to manoomin. Sulfide is a product of anoxic sulfate reduction by bacteria. Sulfate is an oxidation product of iron sulfide, which is released by regional mining activity. We hypothesize that sulfate is entering the lake via atmospheric dust transported from local mining basins. To test this and improve existing monitoring practices, this study determined baseline geochemical conditions at BRL for porewater and surface water (sulfide and major anions and cations), and sediment (acid volatile sulfide and iron). These measurements were then compared to existing data from other Minnesota manoomin lakes to contextualize our results. Preliminary results indicate presence of sulfide at BRL, so we propose to deploy dust traps, as a way for tribal resource managers to better monitor sulfate transport.