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ST. LAWRENCE INFO
Lake Ontario: The Main Source of Herbicides in the St. Lawrence River
The Great Lakes are far and away the greatest source of contamination by herbicides (atrazine, simazine and cyanazine) in the St. Lawrence River. The analytic results of a team of scientists from Environment Canada found that Lake Ontario was the source of 90% of the triazines measured in the St. Lawrence River in the 1990s.
In general, herbicide concentrations in the St. Lawrence are higher in summer, corresponding with the period of pesticide application. The origin of these sporadic increases in herbicide concentrations, however, are the St. Lawrence tributary rivers that flow through farming areas. These rivers are responsible for 10% of the quantities measured during the summer.
To find out more, consult the following paper at NRC Research Press:
Pham, T. T., B. Rondeau, H. Sabik, S. Proulx, and D. Cossa. 2000. Lake Ontario: The predominant source of triazine herbicides in the St. Lawrence River. Canadian Journal of Fisheries and Aquatic Sciences 57: 78-85.
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