Degradation of Plastic Waste in the Marine Environment

Annual global plastic production reached 360 million tonnes in 2018, with only 20% of the plastic waste being recycled. It has been predicted that production will double in the next 20 years. This review summarizes the occurrence, effects, and pathways as well as the degradation mechanisms and rates of different types of plastic waste in the marine environment. Approximately 75% of the litter found in the marine environment is mainly plastic, including polyethylene, polypropylene, polyethylene terephthalate, and polymers. Marine plastic waste has been found to accumulate in the open sea and deep sea and on beaches and shorelines of most remote areas, even in Arctic sea ice. Because of its durable and corrosion-resistant properties, plastic waste tends to accumulate and persist in the marine environment. The interaction of plastic waste with environmental conditions results in chemical, physicochemical, and biological degradation of the plastic waste and thus changes in its surface properties. Thus, both physical and chemical impacts from the degradation of plastic waste threaten marine organisms and even human health. Finally, some sustainable practices are suggested for the bioremediation of plastic waste.