Microplastic pollution in the marine environment: A review

The quantity of plastic materials produced worldwide is progressively increasing. For instance, annual global plastic production has increased from 1.5 to 390.7 million metric tons from 1950 to 2021. Meanwhile, inefficient management strategies have resulted in huge plastic waste disposal (i.e., in the form of macro-, micro-, and nanoplastics) in the environment in a hostile manner. In particular, such uncontrollable waste discarding paves the entrance of plastic pollution into the environment as microplastics (μPs) after the degradation of macroplastics. In this respect, marine environments are the most typical regions prone to μP pollution. These ubiquitous emerging pollutants can also adsorb other pollutants, such as organic materials, toxic heavy metal ions, and pathogens, from the environment and transfer them into living organisms. The main theme of the present study is to compile information on how μP pollution affects the marine ecosystem, with a particular emphasis on the following key factors: (i) the types and sources of μPs, particularly those entering the marine sinks; (ii) the mechanisms leading to μPs' degradation; (iii) the poisonous effects of μPs on marine biota and humans; (iv) the fate of μPs in the marine environment, including their transportation routes and deposition modes, and (v) recent developments in the characterization, separation, and removal of μPs from the marine environment. The information presented here would be practical for developing effective μPs' risk management plans.