SS3.17 Global Mercury Cycling: From Natural to Anthropogenic Sources
Date: Tuesday, June 11, 2002
Time: 11:45:00 AM
Location: Carson C
ManolopoulosH, Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, USA,
Hurley, J, P, Water Resources Institute, University of Wisconsin-Madison, Madison, USA, 
Rolfhus, K, R, Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, USA, 
Back, R, C, Department of Biology, Lake Superior State University, Sault. Ste. Marie, USA, 
Previous work on Lake Superior revealed very low concentrations (0 to 65 fM) of methyl mercury (MeHg) in the offshore waters using direct ethylation techniques. The highest levels were measured in the western arm of Lake Superior, more specifically at sites close to Duluth-Superior (Rolfhus et al., in preparation). Furthermore, other work on tributaries within the Lake Superior Basin showed riverine concentrations of MeHg to be much higher ranging from 0.25 to 1.1 pM, depending on the individual watershed characteristics (Hurley et al., 2001; Babiarz, 2001). These observations prompted us to investigate the occurrence of mercury species in Lake Superior to determine the sources and pathways of MeHg to the nearshore waters of the lake. We hypothesize that riverine mixing zones represent the key regions for MeHg bioaccumulation in the lake.