Composition, spatial distribution and sources of plastic litter on the East China Sea floor

Plastics are present in all marine waters around the globe, often at high abundances and they are potentially harmful to marine organisms. In this study, we investigated the regional distribution, composition, and abundance of plastic items on the floor of the East China Sea based on 43 bottom trawl samples collected during 2019. Considerable geographical variation was detected. Polyethylene was the most abundant polymer type where it accounted for 42.83% by weight. The surface areas and lengths of the plastic items ranged from 3.43 to 2842 cm² and from 1.3 cm to 14.23 cm, respectively. The plastic density was 18.94 kg/km² in Sanmen Bay but it was significantly lower at 2.24 kg/km² in Wenzhou Bay. Fishing gear represented 23.87% of the plastic items. The plastic items found on the coastal sea bed were probably transported and moved during upwelling and downwelling processes, and finally deposited on the seafloor due to the effect of biofouling. The accumulation of macro- and mesoplastics could have detrimental impacts on seafloor ecosystems.