Enantioselective Degradation Behavior and Influencing Factors of Chiral Imazalil in Different Soils

Substantial application of chiral pesticides represented by imazalil in agricultural practices tends to cause significant accumulation of inefficient or ineffective enantiomers in soils. However, the factors affecting the enantioselective degradation of imazalil in soils, such as physicochemical properties and the indigenous microbial community composition, have not been adequately studied. This study characterized the degradation of imazalil in soils from four sites, explored the effects of soil physicochemical properties on the degradation of imazalil by comparing the degradation rate (half-lives) and evaluated the effects of microbial factors on the enantioselective degradation of imazalil by considering the indigenous microbial community composition in different soils. The degradation half-lives of the imazalil enantiomers ranged from 14.15 to 20.81 d. Higher total nitrogen content and organic matter content could promote the degradation rate of imazalil. Significant enantioselectivity was observed in the dissipation process of imazalil in Guangdong soil (acidic soil). Soil fungi exhibited greater impacts on the degradation of imazalil in a richness- and diversity-dependent manner than bacteria. The half-life of (+)-imazalil enantiomer was significantly negatively correlated with the richness and diversity of fungal community. The above results indicated that soil physicochemical properties affect the degradation rate of imazalil, and soil pH and microbial community composition may be the major driving forces for the enantioselective degradation of imazalil enantiomers.