Contamination of Lake Water by Pesticides via Atmospheric Transport

Abstract

High altitude lakes cannot be contaminated by a direct introduction of xenobiotic chemical compounds such as pesticides. Nevertheless they can be contaminated by these compounds after meso scale atmospheric transport. Laboratory experiments were carried out to determine the life time of pesticides in the atmosphere. Simulation of atmospheric degradation by UV and/or atmospheric oxidants of pesticides absorbed on terrigenic aerosols (kaolin) or anthropic aerosols (fly ash) shows that some pesticides such as atrazine, simazine or trifluraline have sufficient life times to be transported over several hundred miles from the source areas to the receptor sites and then contaminate the water after wet or dry deposition, while other pesticides such as diuron, carbaryl or fenitrothion are rapidly destroyed during atmospheric transport and cannot reach remote areas. Simultaneously, field measurements were carried out in the Savoy region in France to see if these pesticides were present in the troposphere and in the Alpine lake water. Significant amounts of atrazine, simazine, pendimethalin, and trifluralin were found both in the air and in the water, while no trace of isoproturon, diuron and fenitrothion were detected in the atmosphere in accordance with their expected life times. The presence of carbaryl, however, in lake water is strange since this compound has a short life time. These preliminary results will be used to keep track of the water in parallel with ecotoxicological tests and biochemical assays.