Effects of polyamide and polymethyl methacrylate microplastics on environmental behaviors of iprodione in soil

Organic pollutants in the environment may be absorbed by microplastics, which may affect the degradation, adsorption and migration of pesticides in soil. The impact is related to the types of microplastics and pesticides. To clarify the effects of microplastics on the environmental behavior of iprodione in soil, the impacts of microplastic of polyamide (PA) and polymethyl methacrylate (PMMA) on the adsorption, migration, leaching and degradation of iprodione in soil were investigated under simulated indoor conditions. The results showed that the soil sorption constants (K_f) of soil with 2% PMMA and soil with 2% PA were 2.9 and 1.2 times higher than those of the control soil, respectively. The adsorption capacity of soil for iprodione increased with the increase of pH in the range of pH 4-7. The R_f values of iprodione in the control soil, soil with 2% PA and soil with 2% PMMA were 0.12, 0.097 and 0.091, respectively. The concentration of iprodione in the first soil column of the control soil, soil with 2% PA and soil with 2% PMMA were 85.4%, 100% and 100%, respectively. The degradation half-lives of iprodione in the control soil, soil with 2% PA and soil with 2% PMMA were 19.8, 26.7 and 40.8 d, respectively. Microplastics reduced the mobility and prolonged the soil degradation half-life of iprodione by enhancing the soil sorption capacity of iprodione, which aggravated the threat of pesticide to the surface soil environment.