Impacts of plastic mulch - derived microplastics on soil carbon cycling: a review

Soil microplastic pollution has become a global environmental issue, among which agricultural soil mulch-derived microplastic pollution is receiving increasing attention. This paper systematically reviews the direct and indirect impact mechanisms of traditional mulch and biodegradable mulch-derived microplastics on the contents of soil organic carbon, inorganic carbon and microbial biomass carbon at home and abroad; explores the regulatory effects of different types of microplastics on soil enzyme activities related to soil carbon cycling; compares the differential impacts of traditional and biodegradable mulch-derived microplastics on the structure of soil carbon cycling -related microbial communities, functional gene abundance and carbon metabolic pathways; reveals the key functional species enriched in the microplastic sphere and their potential role in promoting the conversion of microplastic carbon to soil carbon; and investigates the influence of residual microplastics on soil viral communities and their mediated soil carbon cycle processes. Based on the current research progress, key research avenues on mulch-derived microplastics in agricultural ecosystems are proposed, which provides some research ideas and references for future exploration of the potential impact of microplastic pollution on soil carbon storage in farmland.