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LAKE MICHIGAN MASS BALANCE STUDY: PROGNOSIS FOR PCBS
Citation:
Kreis, R G., G. Gerstner, D D. Endicott, M. C. Warren, K R. Rygwelski, X. Zhang, P. Horvatin, K. WissingTaunt, AND W. Melendez. LAKE MICHIGAN MASS BALANCE STUDY: PROGNOSIS FOR PCBS. Presented at Lake Michigan State-of-the-Lake Conference, Muskegon, Michigan, October 21-22, 2003.
Description:
The Lake Michigan Mass Balance Study was conducted to measure and model nutrients, atrazine, PCBs, trans-nonachlor, and mercury to gain a better understanding of the transport and fate of these substances within the system and to aid managers in the environmental decision-making process. --- The mass balance results demonstrate the importance of contaminant cycling and the dynamic interactions between air, water, and sediments. These interactions, with present PCB inventories already in the lake, will continue to control PCB concentrations in the system.
The MICHTOX model was also used to forecast future concentrations of PCBs in lake trout at Saugatuck, MI, under different loading scenarios. Scenarios included no further remedial action, virtual elimination, and various combinations of reduced atmospheric and tributary loadings. Forecasts predicted that PCB concentrations in lake trout will continue to decrease. The target level for the unrestricted consumption of fish was forecasted to be achieved for 5/6 year old lake trout between the years 2020 and 2030 in all load reduction scenarios. The narrow forecast range for scenarios, past actions, the long-term decrease in loads, and decreasing PCB concentrations in the system indicate that PCB concentrations are presently controlled by dynamic interactions among media and PCBs presently in the system. MICHTOX results will be compared to higher-resolution models in the future for agreement. It is anticipated that the higher resolution models will further delineate nearshore processes, interactions with tributary inputs, and will allow a more resolute assessment of PCBs in lake trout pupulations.