Impact of biosolids, ZnO, ZnO/biosolids on bacterial community and enantioselective transformation of racemic-quizalofop-ethyl in agricultural soil.

The effects of biosolids, ZnO, and ZnO/biosolids on soil microorganism and the environmental fate of coexisting racemic-quizalofop-ethyl (rac-QE) were investigated. Microbial biomass carbon in native soil, soil/biosolids decreased by 62% and 52% in the presence of ZnO (2‰, weight ratio). The soil bacterial community structure differed significantly among native soil, soil/biosolids, soil/ZnO, and soil/biosolids/ZnO based on a principal co-ordinate analysis (PCoA) of OTUs and one-way ANOVA test of bacterial genera. Chemical transformation caused by ZnO only contributed 4% and 3% of the overall transformation of R-quizalofop-ethyl (R-QE) and S-quizalofop-ethyl (S-QE) in soil/ZnO. The inhibition effect of ZnO on the initial transformation rate of R-QE (r) and S-QE (r) in soil only observed when enantiomer concentration was larger than 10 mg/kg. Biosolids embedded with ZnO (biosolids/ZnO) caused a 17%-42% and 22%-38% decrease of r and r, although r and r increased by 0%-17% and 22%-58% by the addition of biosolids. The results also demonstrated that the effects of biosolids on agricultural soil microorganism and enantioselective transformation of chiral pesticide was altered by the embedded nanoparticles.