Levels of selected pesticides in farm ditches leading to rivers in the lower mainland of British Columbia

Abstract

A monitoring survey was conducted from 1985 to 1987 to determine the levels of agricultural pesticides azinphosmethyl, diazinon, dinoseb, endosulfan, and fensul fothion in selected farm ditches leading to the Lower Fraser, Nicomekl, and Sumas rivers in British Columbia, Canada. In ditch water, azinphosmethyl, diazinon, endosulfan, and fensulfothion were not detected (limit of detection, 1 μg/L). However, dinoseb was consistently found in ditch water for one year after the spray season at levels varying from 0.3 ‐ 18.6 μg/L, averaging 4.9 μg/L. The endosulfan level in ditch water of one farm reached 1530 μg/L shortly after a spray application, even though it was not found at other times of the year. In ditch sediments, low levels, i.e., 2.7, 4.0, 22.9 and 10.3 μg/kg respectively of azinphosmethyl, diazinon, dinoseb, and fensulfothion were sporadically found. Endosulfan was, however, consistently found in sediments at all study sites at levels varying from 2 ‐ 150 μg/kg, averaging 18.8 μg/kg.