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THE LOADINGS, TRANSPORT, AND FATE OF ATRAZINE IN LAKE MICHIGAN
Citation:
Rygwelski, K R. AND W. L. Richardson. THE LOADINGS, TRANSPORT, AND FATE OF ATRAZINE IN LAKE MICHIGAN. Presented at 2001 Annual International Association for Great Lakes Research Conference, Green Bay, WI, June 10-14, 2001.
Description:
A lake wide atrazine model was developed to gain insight into the transport and fate of the herbicide in Lake Michigan. An important part of the analysis was the preparation of historical loading estimates from both tributaries and the atmosphere. Historical tributary loading estimates were made based on a six year record of actual amounts of atrazine applied to corn crops in the basin. Based on those estimates, loads were predicted for other years where only total annual usage of atrazine used in the USA was available. For the period of 1994 and 1995, the statistically-based Stratified Beale comparison of SBRE loads to estimates made based on county-level application of the chemical were made. Loads calculated by the USGS were approximately one-third or less than estimates made by the other method. Atmospheric loading estimates were made based on observed wer desposition fluxes and applied to predict loadings for years when only total annual USA dosage amounts were available. A whole-lake MICHTOX model prediction of atrazine in the lake water suggests that atrazine is decaying at a rate of less than or equal to one percent per year.