Microplastic-derived dissolved organic matter and its biogeochemical behaviors in aquatic environments: A review

Microplastic-derived dissolved organic matter (MP-DOM) exerts great effects on organic carbon pool and its environmental behaviors in natural waters due to increasing amounts of uncontrolled plastic disposal. However, systematic understanding of chemical composition and environmental impacts of MP-DOM in aquatic systems was limited. In this work, the chemical and molecular structures of MP-DOM derived from diverse characterization methods were examined and synthesized to provide a basis for understanding their environmental processes. Additionally, those factors affecting the quantity and quality of released MP-DOM (e.g., plastic types, water environments, and external weathering conditions) were reviewed. Furthermore, environmental behaviors of MP-DOM including its biological degradation, adsorption on mineral surfaces, and interaction with pollutants, as well as their environmental impacts were comprehensively summarized. Finally, we outlooked the future research directions on MP-DOM studies, aiming to contribute to a deeper understanding of the environmental mechanisms and control of plastic pollution through the analysis of MP-DOM. This review provides information for further understanding the impact of microplastics on natural water, which might have consequences on the fluxes of carbon and biogeochemical behaviors of metal and organic contaminants.