Occurrence, Fate, and Biodegradation of Microplastics in Marine Environments

The ubiquitous and recalcitrant nature of synthetic polymers contributes extensively toward xenobiotic pollutants entering the marine environments. Microplastics (≤5-mm fragments) are extensively distributed emerging contaminants present in the marine ecosystems. In general, microplastics comprise polyvinyl chloride, polyethylene terephthalate, polystyrene, nylon, etc. Due to deficiency of effective treatment technologies, the amount of microplastics is expanding at a dismaying rate, thus causing hazardous impact on the marine ecosystem and raising a global concern. The minute particle size of microplastics enables for its enhanced pathways in the aquatic food web and element cycles. Further, other organic and inorganic pollutants present in the marine environment can readily adhere to microplastics, which then function as active carriers for a wide range of contaminants in aquatic food webs. Processes such as weathering, degradation (microbial, oxidative, and hydrolytic), aggregation, and biofilm production have been reported to impose significant impact on transport of microplastics in the aquatic ecosystem. This chapter provides a deep insight into sources, distribution, fate, and toxic impact of microplastics in the environment. In addition, the role of marine microbes in the degradation of microplastics has also been explored.