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Model Forecasts of Atrazine in Lake Michigan in Response to Various Sensitivity and Potential Management Scenarios
Citation:
RYGWELSKI, K. R., X. ZHANG, AND R. G. KREIS. Model Forecasts of Atrazine in Lake Michigan in Response to Various Sensitivity and Potential Management Scenarios. JOURNAL OF GREAT LAKES RESEARCH. International Association for Great Lakes Research, Ann Arbor, MI, 38(1):1-10, (2012).
Impact/Purpose:
To document research results.
Description:
For more than forty years, the herbicide atrazine has been used on corn crops in the Lake Michigan basin to control weeds. It is usually applied to farm fields in the spring before or after the corn crop emerges. A version of the WASP4 mass balance model, LM2-Atrazine, was used to assess the impact of the historical and future usage of this chemical on lake water concentrations. The greatest atrazine loads to the lake are from the watershed. Model results indicate that net volatilization is negligible, and the greatest loss from the lake is due to export to Lake Huron. Long-term model forecasts were performed under various sensitivity and potential management scenarios. Model results indicate that atrazine, under average conditions, is decaying very slowly in the lake (0.009/yr). This kinetic decay translates into a half-life estimate of 77 years. If the average condition scenario were assumed to remain constant into the future and reflective of conditions in January 1, 2005, it is expected that the lake would eventually reach an average atrazine concentration of approximately 66 ng/L. That forecast would increase to an estimate between 75 and 84 ng/L if increased atrazine usage results from higher corn production associated with the ethanol biofuel program. All of these average lake-wide forecasted concentrations are below known water quality criteria for the protection of aquatic ecosystems
URLs/Downloads:
Model Forecasts of Atrazine in Lake Michigan in Response to Various Sensitivity and Potential Management Scenarios