Occurrence of Pesticides in Prairie Lakes in Saskatchewan in Relation to Drought and Salinity
- David B. Donald * and
- Jim Syrgiannis
Prairie lakes are critical breeding, staging, and feeding habitat for a variety of shorebirds and waterfowl, and lower trophic levels in these habitats could be affected by agricultural pesticides. Following the severe drought of 1988 in Saskatchewan, concentration of 11 pesticides were determined in water, sediment, and zooplankton in 10 permanent and nine semipermanent lakes (those lakes that did not have standing water in 1988). The detection frequency for lindane, α-HCH, and 2,4-D in water was 57, 70, and 78%, respectively, with the maximum concentration 0.011, 0.004, and 0.43 µg/L, respectively. Triallate was detected in 39% of sediment samples and 54% of zooplankton samples at a maximum concentration of 31 and 10.2 µg/kg, respectively. When the lakes were grouped by salinity, detection frequencies of these pesticides were significantly higher in brackish lakes, which tended to be semipermanent (N = 6, mean specific conductance 3100 µS/cm) than in saline lakes, which tended to be permanent (N = 6, mean specific conductance 60 900 µS/cm). Other pesticides were detected in <20% of samples (diclofop-methyl, atrazine, MPCA, dicamba, and bromoxynil) or not at all (trifuralin and picloram). With one exception, pesticide concentrations in these lakes were below those levels that might be deleterious to aquatic life, suggesting that these pesticides have not affected the food of avifauna at these lakes.
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