Fate of major degradation products of Atrazine in Iowa soils

Abstract

Five Iowa soils, sampled at two depths each were treated with ¹⁴C‐deethylatrazine (DEA) and ¹⁴C‐hydroxyatrazine (HYA) and incubated for nine and 17 weeks. ¹⁴CO₂ evolution was monitored over this period. The degradation of DEA was influenced by both soil type and soil depth. For each soil studied, the degradation of DEA was much higher in the surface layer compared to the respective subsurface layer. The major degradation products from DEA included CO₂, soil bound residues, and polar metabolites. Deethylhydroxyatrazine (DEHYA) and didealkylatrazine (DAA) were detected in minor quantities. Increased mineralization of DEA in the extended incubations confirmed the susceptibility of DEA to microbial degradation. In the complete metabolism studies with HYA, the major components identified included HYA, soil bound residues, and CO₂. Deethylhydroxyatrazine deisopropylhydroxyatrazine and ammeline were found in smaller quantities. The relatively long persistence (45 to 69% remaining) of HYA was observed in 3 of the topsoils. HYA persisted well in all of the subsurface layer. There was no evidence of HYA forming significant amounts of bound residues.

Key words:

• ¹⁴C‐deethylatrazine
• ¹⁴C‐hydroxyatrazine
• fate
• degradation
• mineralization