INFLUENCE OF PH, TEMPERATURE AND SEDIMENT TYPE ON THE TOXICITY, ACCUMULATION AND DEGRADATION OF PARATHION IN AQUATIC SYSTEMS

The effects of pH, temperature, and sediment on the toxicity and aquatic fate of parathion were investigated. Acute toxicity tests, accumulation and metabolism studies were conducted with midge larvae, Chironomus riparius, at pH values 4, 6, and 8 in water held at 10°C, 20°C, and 30°C, with and without sediment. Abiotic tests were also performed to determine the fate of parathion under various substrate conditions. Without exception, temperature was the most influential parameter tested. It altered both the toxicity and metabolism of parathion, at times increasing toxicity as much as 100-fold when the temperature increased from 10°C to 30°C. Sediment also influenced parathion toxicity and degradation, although to a lesser extent than temperature. Changes in pH had little influence on parathion toxicity or degradation. The results of these studies further emphasize the importance of abiotic factors on the environmental fate of xenobiotics. © 1990.