Adsorption-desorption and degradation of insecticides clothianidin and thiamethoxam in agricultural soils

作者：Li Yang^*; Su Peidong; Li Yadong^*; Wen Kejun; Bi Guihong; Cox Michael

来源：Chemosphere, 2018, 207: 708-714.

DOI：10.1016/j.chemosphere.2018.05.139

• Clothianidin
• Thiamethoxam
• Soil
• Adsorption
• Desorption
• Degradation
• Fate
• Transport

Studied were the adsorption-desorption and degradation of two widely used neonicotinoid insecticides clothianidin and thiamethoxam in three different agricultural soils in the state of Mississippi. The adsorptions of both the neonicotinoids fit a linear isotherm model. In different soils at different depths with different moisture contents, the adsorption distribution coefficients of clothianidin and thiamethoxam were found to be 0.62 to 1.94 and 0.59-2.03 L kg(-1), respectively. These distribution coefficients showed strong positive correlations with organic carbon content and pH of the soils. The desorptions of clothianidin and thiamethoxam also followed a linear isotherm, but were irreversible in respect to their adsorption isotherms. The desorption distribution coefficients ranged from 0.14 to 0.62 L kg(-1), increased with the decrease of organic carbon content The degradations of clothianidin and thiamethoxam in the soils were found to be slow with half-lives ranged from 90 to 280 and 65 to 170 d for clothianidin and thiamethoxam respectively. The degradation rates increased with the increase of the organic carbon content in the soils. The moisture content in the soils had a positive effect on the degradation rates. The Groundwater Ubiquity Scores calculated from the adsorption distribution coefficient, organic content, and half-life suggest that clothianidin and thiamethoxam have moderate to high potential to leach to groundwater.

• 出版日期2018-9