MP5 Agrochemicals and Pesticides
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(STR-1117-828505) In-use pesticide concentrations in Canadian Areas of Concern of the lower Great Lakes.

Struger, J.¹, Marvin, C.¹, Sverko, E.¹, Dove, A.¹, ¹ Environment Canada, Burlington, ON, Canada

ABSTRACT- Surface water samples were collected in 2002 and 2003 from seven Canadian Areas of Concern (AOCs) in the lower Great Lakes. They include: three sites in the St. Clair River, three sites in the Detroit River, one site in Wheatley Harbour, two sites in the Niagara River, four sites in Hamilton Harbour, three sites in the Toronto AOC and three sites in the Bay of Quinte. Samples were analyzed for triazine, neutral and phenoxy acid herbicides and organophosphorous insecticides. Frequently detected pesticides included atrazine, DEA (desethyl atrazine), metolachlor, 2,4-D and dicamba. Several OP insecticides were also occasionally detected including diazinon and dimethoate. Maximum pesticide concentrations detected were 3060 ng/L for atrazine, 825 ng/L for metolachlor, 580 ng/L for dicamba, 522 ng/L for 2,4-D, 416 ng/L for DEA and 91 ng/L for diazinon. In general, pesticide concentrations increased from AOCs located near Lake Huron to AOCs located in Lake Ontario. Concentrations were highest in AOCs where sampling occurred close to possible pesticide inputs (e.g. Hamilton Harbour, Toronto, and Wheatley Harbour). Concentrations were lower in AOCs that received less direct input such as the St. Clair, Detroit and Niagara rivers and the Bay of Quinte. Aquatic life guidelines were rarely exceeded.

Key words: pesticides, surface waters, Great Lakes, AOCs