Investigation of pesticides in rainwater at Isogo Ward of Yokohama

Abstract

Large amounts of various pesticides have been used in farms, rice paddies and gardens. However, few studies on the pesticides in rainwater have been conducted in Japan. Thus, rainwater samples were collected from August 2001 until July 2002 at Isogo Ward of Yokohama, and 51 kinds of pesticides in the 51 samples were investigated. Although sampling point was not located in the agricultural area, dichlorvos (0.33-0.05 μg/l), chlorothalonil (0.27-0.05 μg/l), fenitrothion (0.24-0.05 μg/l), molinate (0.12-0.05 μg/l), diazinon (0.07-0.05 μg/l), and malathion (0.05 μg/l) were detected. Dichlorvos was the most frequently detected (65% of samples) and its highest concentration in rainwater (0.33 μg/l) was found on May 7, 2002. Chlorothalonil was the second most frequently detected (33% of samples) and its highest concentration in rainwater (0.27 μg/l) was found on May 26, 2002.