Affiliations: Institute of Environmental Science, Zhongshan
University, Guangzhou 510275, China. E- mail: eeslsy@ zsu. edu. cn | Department of Environmental Engineering, Osaka
University, Yamada-oka 2-1, Suita, Osaka 565, Japan. E - mail: morioka@env.eng.
osaka-u. ac. jp
Abstract: The risk of drinking water is greatly concerned because of the large
amount of pesticide applied to paddy field and the contamination of drinking
water sources due to the runoff. A mathematical model is developed, based on
the mass balance, to predict the fate of paddy field pesticides from
application, runoff and mixing in a river, taking account of the
physical-chemical properties and processes of volatilization, degradation,
adsorption and desorption. The model is applied to a river basin in Japan to
estimate the contaminant level of several popularly used pesticides at the
water intakes. The health risk in drinking water induced by each pesticide
concerned is estimated and evaluated by comparing with the acceptable daily
intake values (ADI) and with that induced by trihalomethanes. An index to
evaluate the total risk of all pesticides appearing in water is proposed. The
methods for risk management are also discussed.
