Monitoring Agricultural Drainage Ditches and the Receiving Water (Nicomekl River, Surrey, B.C.) for Toxicity to Ceriodaphnia dubia and Probable Cause Due to Organophosphate Contamination

摘要

The use of organophosphate insecticides on commercial vegetable and blue- berry farmlands bordering the Nicomekl River, Surrey, B.C., creates the poten- tial for toxic effects on the biota within the drainage ditches and the river itself. To investigate the frequency and magnitude of the toxicity of drainage ditch water and the river water in the vicinity of ditch discharge points, together with the probable cause, water samples were collected from six drainage ditches, and four river locations, at 3-week intervals between June and November 1997. For each of the water samples collected, chronic (7 ± 1 day) survival and reproduc- tion of the cladoceran test organism Ceriodaphnia dubia were compared to that of Nicomekl River headland waters beyond the influence of commercial grow- ing operations. Portions of samples proving to be lethally toxic to the toxicity- test organism were analyzed for organophosphate insecticides (OPs) and sub- jected to treatment with piperonyl butoxide to ascertain if OPs were the likely contributing cause of the toxicity.