Pesticides in Water and Sediment from Littoral Area of Lake Biwa

A survey of 29 pesticides was performed for water and sediment from two littoral areas of Lake Biwa in 2007. Two insecticides, 5 fungicides and 13 herbicides in the water and an insecticide, 4 fungicides and 7 herbicides in the sediment were detected from the present survey. Pesticide accumulation potential in the sediment was calculated as Pesticide concentration ratio from the results of the survey on water and sediment in Lake Biwa. Correlation was investigated for each of the detected pesticides between sediment ignition loss and pesticide concentration ratio or between sediment particle size and pesticide concentration ratio. The ignition loss correlated well with the pesticide concentration ratio for pyrokiron, simetryn, and isoprothiolane (p < 0.01 to p < 0.001) but did not for molinate, bromobutide and pretilachlor. Further, the < 0.025 mm particle size ratio correlated well with the pesticide concentration ratio for pyrokiron, simetryn, flutolanil, isoprothiolane and mefenacet (p < 0.01 to p < 0.001) but did not for bromobutide and pretilachlor. The correlation between < 0.025 mm particle size ratio and pesticide concentration ratio had almost the same tendency as that between ignition loss and pesticide concentration ratio, suggesting sediment with higher < 0.025 mm particle size ratio had higher weight (%) of ignition loss.