Degradation of [ 14 C]Terbuthylazine and [ 14 C]Atrazine in Laboratory Soil Microcosms

✍ Scribed by Dousset, Sylvie; Mouvet, Christophe; Schiavon, Michel

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 236 KB
• Volume: 49
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1096-9063(199701)49:1<9::aid-ps472>3.0.co;2-f

✦ Synopsis

The degradation and formation of major chlorinated metabolites of terbuthylazine and atrazine in three soils (loamy clay, calcareous clay and high clay) were studied in laboratory experiments using molecules labelled with 14C on the s-triazine ring. Soil microcosms were treated with the equivalent of 1 kg ha~1 of herbicide and incubated in the dark for 45 days at 20(^1)¡C. The quantity of [14C]carbon dioxide evolved in the soils treated with atrazine was negligible and could not be attributed to mineralization of the parent molecule. The mineralization of terbuthylazine accounted for 0É9È1É2% of the initial radioactivity. In the soils studied, the extrapolated half-lives varied from 88 to 116 days for terbuthylazine and 66 to 105 days for atrazine, with no signiÐcant di †erences for the three soils and the two molecules. The deethyl metabolites of the two s-triazines and the deisopropyl-atrazine metabolite appeared during the incubation in the three soils. The completely dealkylated metabolite was not detected in any of the soils. After 45 days of incubation, the non-extractable soil residues for the high clay, loamy clay and calcareous clay soils represented for terbuthylazine, 33É5, 38É3 and 43É1% and for atrazine, 19É8, 20É8 and 22É3% of the initial radioactivity.