Bioavailability of neonicotinoid insecticide paichongding in three typical soils
An in-lab simulation experiment was conducted to investigate the degradation and bioavailability of paichongding,a neonicotinoid insecticide,in three soils.The test model organism was the earthworm(Eisenia foetida),while paichongding served as the target pollutant.Bioaccumulation in earthworms and indirect bioassay were used to assess the bioavailability of paichongding in the three soils.The results indicated that the half-life values of paichongding in brown,red,and black soils were 11.45-12.62,12.42-14.38 days,and 5.19-10.21 days,respectively.The degradation rates of paichongding in the three soils followed this order:black soil>brown soil>red soil.The bioaccumulation of paichongding in earthworms increased in the soil with higher concentrations of paichongding.Under the treatment of 10 mg·kg-1 in brown,red,and black soil,the concentrations of paichongding in earthworms were 190,210 ng·g-1,and 160 ng·g-1,respectively.The bioaccumulation results revealed that the bioavailability of paichongding was low in black soil,while it was relatively high in red and brown soils.Earthworms subjected to paichongding exhibited oxidative stress,resulting in significant differences in protein content,antioxidant enzyme activity,glutathione-S-transferases activity,and malondialdehyde content.The impact was relatively minor in black soil but significant in brown and red soils.The bioavailability was weaker in black soil with higher organic matter content and stronger in brown and red soils.
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