Microplastics in marine systems: A review of sources and sinks, typical environmental behaviors, and biological effects

Marine microplastics (MPs), whether originating from household and industrial production or stemming from the degradation of larger plastic fragments, have currently attracted significant global attention among the scientific community. The transport and deposition of MPs, characterized by their small size and large quantity, under oceanic hydrodynamics result in the contamination of a wide range of areas. Furthermore, MPs are capable of carrying metals and organic pollutants that constitute composite pollutants. The additives it carries will gradually release harmful substances during the degradation process. Once ingested by aquatic organisms and amplified by the food chain, these pollutants can adversely affect the survival and growth of marine flora and fauna, ultimately posing potential threats to humans. In this review, the major sources and sinks of MPs are described, considering the pollution of marine ecosystems. Additionally, typical environmental behaviors of MPs including their migration and accumulation in the ocean, their combined ability with heavy metals and organic pollutants, their leaching of additives, and their abiotic and biotic degradation pathways are discussed. The adverse effects on marine organisms resulting from ingestion and translocation of MPs are also reviewed herein. Even though the number of studies on MPs-associated environmental impacts is increasing rapidly, this review underscores that there is a pressing necessity to achieve an integrated assessment of MPs' impacts on marine ecology in order to address existing and future knowledge gaps.