Degradation of terbutryn in sediments and water under various redox conditions.

A laboratory study was conducted to examine the degradation of terbutryn [2-(t-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] in sediment and water under different redox conditions. Terbutryn degraded slowly in static aerobic systems (loosely capped flask, 25 degrees C) with half-lives of 240 and 180 days in pond and river sediment, respectively. Degradation products, identified by co-chromatography on TLC and HPLC systems, included hydroxy-terbutryn, terbutryn-sulfoxide and N-deethyl terbutryn. Hydroxyterbutryn was the major degradation product in sediments and water representing 60-70% of the extractable radioactivity after 515 days incubation. Under nitrogen aeration in respirometer flasks (redox potential -46 to +210 mv) degradation of terbutryn was very slow with half lives greater than 650 days.