|Wu, J - IOWA STATE UNIVERSITY|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 2000
Publication Date: N/A
Technical Abstract: The fate of chlorphyrifors in aquatic environments is largely governed by its degradation and transformation in water. The effects of aqueous solutions with different electrolyte backgrounds and smectitic clays on the degradation of chloryrifos were investigated. Solid phase extraction and HPLC techniques were employed to determine concentrations of chlorpyrifos and its degradation product, TCP (3, 5, 6-trichloro-2- pyridinol), in various chlorpyrifos solutions incubated in amber bottles at 23+/-2C over different time intervals. The results indicate that chlorpyrifos degraded rapidly in aqueous solutions with half-lives ranging from 25 to 150 days, depending on the initial concentration of chlorpyrifos and aqueous solution composition. The rate of degradation of chlorpyrifos was lower in the presence of smectites than in the absence of smectites in 0.01 M CaC12 solutions, suggesting that sorption of chlorphrifos on clays inhibited the degradation process in clay-water systems. This effect implies that sorption on clays may prolong the toxicity of chlorpyrifos in aquatic environments. It was also found that smectites catalyzed transformation of phlorpyrifos to an unknown product in clay-water suspensions while this transformation process was not found in aqueous solution without smectites.