Adsorption Behavior of Microplastics as a Carrier of Various Contaminants and Their Ecotoxicity in Aquatic Environment

Objectives Microplastics are released into the aquatic environment through multiple pathways including runoff, atmospheric sedimentation, aquaculture, and fishing and pose a hazard to organisms. Public concerns regarding microplastics are raising as microplastic pollution increases. A lot of studies have been evaluated the behavior of microplastics in the environment, suggesting that microplastics remain a prolonged period in the environment due to their persistence and can interact with other contaminants. Microplastics as carriers of coexisting contaminants may pose a more severe toxicity to organisms than microplastics alone. In this study, we investigated the behavior of microplastics as carriers of environmental contaminants and introduced a potential ecotoxicity of microplastics carrying other contaminants. Methods The behavior of microplastics as carriers of contaminants were classified as adsorption mechanisms. Research literature regarding ecological risk of microplastics carrying contaminants was reviewed in papers published between October 2003 and August 2023. Results and Discussion Adsorption of contaminants onto microplastics are mainly involved in hydrophobic interaction, electrostatic interaction, hydrogen bond, and Van der Waals forces. The co-exposure of microplastics with contaminants to organisms can induce oxidative stress and bioaccumulation and reduce the survival and reproduction rates, chlorophyll content, and photosynthetic efficiency. On the other hand, a few studies reported that the co-exposure of microplastics with contaminants can decrease the toxicity to organisms. Conclusion This paper provides basic information regarding the adsorption interactions of microplastics with diverse contaminants and their ecological effects on organisms. The contents will help to understand a potential function of microplastics as a carrier of coexisting contaminants in aquatic environment and their biological risk.