Microplastics derived from polymer-coated fertilizer altered soil properties and bacterial community in a Cd-contaminated soil

With the extensive use of polymer-coated fertilizer, microplastics (MPs) pollution in agricultural soil raises worldwide concerns. While very few studies focalized the effects of polymer-coated fertilizer MPs exposure to acid-contaminated soil. Changes in soil properties, enzymatic activity, and microbial community structure were investigated via the addition of 0.1 % and 1 % (w/w) of polyethylene (PE) and polyurethane (PU) in acid soil. The results showed that two types of MPs addition decreased soil pH and MBC contents, stimulated DTPA (cadmium extracted by diethylenetriamine-pentaacetic acid)-Cd (extracted cadmium) contents, beta-glucosidase (BG) and N-acetyl-b-glucosaminidase (NAG) activities significantly. The diversity and richness of fungi was dropped sharply after the addition of 0.1 % PE and PU MPs, but there was the opposite result in fungi. The relative abundance of phylum Mortierellomycota increased significantly in 1 % PE and PU treatments, inferring that the fungus associated with the degradation of recalcitrant carbon source in soil enhanced by the input of MPs. Overall, our research demonstrated that there is still a risk of increased metal bioavailability with the addition of polymer-coated fertilizer MPs, but the fluctuation of soil enzymatic activities and microbial com-munity structure were much more pronounced affected by soil properties via the addition of PE and PU in soil.