VOLATILIZATION OF METOLACHLOR FROM WATER

The volatilization of metolachlor ylphenyl)N-(2-methoxy-1-methylethyl) acetamide]from water was studied in the laboratory and in an outdoor o pen-channel experiment. As expected, volatilization was not significan t at temperatures less than or equal to 25 degrees C. However, at temp eratures greater than or equal to 30 degrees C, there was significant volatilization (e.g., half-life of 20 days at 40 degrees C in unstirre d solutions). This increased volatility reflected the rapid increase o f the Henry's law constant with temperature. Additional experiments in dicated that aeration of water significantly accelerated volatilizatio n losses. Such air-stripping may be important in very turbulent stream s and rivers and when water flows over hydraulic structures such as we irs. The experiments reported here indicate the importance that ecosys tem-specific characteristics can have on the persistence of environmen tal contaminants.