Uptake, translocation, and metabolism of thiamethoxam in soil by leek plants

Abstract

Thiamethoxam (TMX) is commonly applied on leek plants by root irrigation. It might be taken up by leek plants and thus has lasting dietary risk. In this study, the uptake, translocation, and metabolism of TMX in leek plants were investigated. The results obtained from both the hydroponic and soil experiments indicated that TMX could be easily translocated upward and accumulated in leek shoots after being absorbed by roots. The total absorbed TMX amount (M_total) in leek plants from the tested soils varied greatly with its adsorption governed by soil characteristics. Interestingly, M_total was closely correlated with the concentration of TMX in in situ pore water, indicating that TMX in in situ pore water could be a useful approach to predict uptake of this chemical by leek plants from various soils. Profoundly, clothianidin (CLO) was detected with concentration of 0.07-1.54 mg/kg in roots and 0.27-4.12 mg/kg in shoots at 14 d, respectively, suggesting that TMX is easily converted into CLO in leek plants. The results showed that TMX used in soil is easily absorbed by leek and accumulated in edible parts accompanying with formation of CLO.

Keywords: In situ pore Water; Metabolism; Thiamethoxam; Translocation; Uptake.