A Review of Microplastics in Aquatic Sediments: Occurrence, Fate, Transport, and Ecological Impact

Purpose of Review Microplastic (MP) pollution is a global concern due to its prevalence and persistence in the environment. Aquatic sediments, particularly marine sediments, are considered as the potential final sink of this pollution. This review summarizes (1) the fate and transport of microplastics (MPs) in waters and aquatic sediments and (2) the ecological impact of MPs, including the interactions between MPs and microbiome, and the effects of MPs on living organisms in aquatic sediments. Recent Findings Characteristics of MPs, water movement, and weathering conditions determine the fate and transport of MPs. These factors influence MPs' travel and inclination to settle. The interactions of MPs and microbiome can alter bacterial communities, cause MPs' biodegradation, and facilitate biofouling that subsequently changes the fate and transport of MPs. MP presence poses exposure risks to benthic organisms through direct ingestion or trophic transfer, negatively affecting not only individual organisms but also the fauna. Summary The destiny of MPs is affected by many factors, from MPs' characteristics to water movement and weathering. Thus, future research is warranted to develop comprehensive modeling tools that include all the key factors to better understand and predict the fate and transport of MPs in aquatic environments and sediments. The potential impact from the exposure to MPs on the ecosystem of aquatic sediments is relatively less studied. More research is needed in this area, particularly from a systematic level, to understand how different biotic and abiotic factors will interact together and what the consequential impact of these interactions on ecological and human health are.