Eco-Corona of Microplastics in Soil Inhibits Their Role as a Contaminant Vector While Enhancing Their Role as a Microorganism Vector

Microplastics are an environmental vector for both chemical contaminants and microorganisms. Key to this role is the formation of an eco-corona on microplastic surfaces, which influences surface interactions with the surrounding environment. To better understand this, we investigated the composition and formation mechanism of the eco-corona on the surface of microplastics from soil metabolites, and how this affected the sorption of organic contaminants and the colonization of early biofilms. Soil metabolites formed an eco-corona on microplastics primarily through van der Waals interactions, resulting in hard and soft eco-corona layers via multilayer adsorption. The eco-corona not only acted as a barrier, partially preventing exogenous organic contaminants sorbing onto microplastics, but also functioned as a novel sorption layer for organic contaminants. Through this combined effect, the eco-corona reduced organic contaminant sorption by 14.4-19.8%. Additionally, the eco-corona accelerated and enhanced the biotic vector role of microplastics by regulating their initial microbial colonization, thereby enhancing deterministic processes in community assembly. Our findings demonstrate that the eco-corona, a surficial component of microplastics, serves as a "second surface" in governing the environmental behavior of microplastics, necessitating its incorporation in risk assessments of microplastics in terrestrial environments.