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LAKE MICHIGAN MASS BALANCE PROJECT: ATRAZINE MODELLING RESULTS
Citation:
Kreis, R G., K R. Rygwelski, AND W. L. Richardson. LAKE MICHIGAN MASS BALANCE PROJECT: ATRAZINE MODELLING RESULTS. Presented at International Association for Great Lakes Research, 2002 Annual Meeting, Winnipeg, Manitoba, Canada, June 2-6, 2002.
Description:
The triazine herbicide, atrazine, is used worldwide to control broadleaf and grassy weeds in agricultural regions. Atrazine is extensively used for corn crops in the midwestern US, the Great Lakes region, and in the Lake Michigan basin and has been cited as an emerging pollutant in the Lake Michigan Lakewide Management Plan. Through the Lake Michigan Mass Balance Project, three models with differing spatial resolutions were developed and applied to investigate the transport, fate, and effects of atrazine. In 1995, the total atrazine load to Lake Michigan was calculated to be 6000 kg/yr and was dominated by tributary inputs (83%). The largest tributary loads were observed from the St. Joseph, Grand, and Fox Rivers. Greatest inputs from tributaries and atmosphere were commonly observed after application during the spring and early summer. Bounding forecasts were computed based upon no further remedial action. 50% and 100% load reduction scenarios. Model forecasted indicated that at present loads, atrazine concentrations in the lake would continue to increase and steady state would be achieved in approximately 200 years. Present and forecasted concentrations will be compared to aquatic life toxicity thresholds for an initial risk characterization. This abstract does not necessarily reflect EPA policy.