Large deep-sea debris dumps that were never recorded before on the seafloor worldwide have been discovered in the submarine canyons to the north of Xisha trough in the South China Sea (SCS). The plastics primarily came from fishery and navigation activities, as implied by the categories of plastics in the dumps. The pollution history of microplastics reconstructed by 210Pb dating shows that the microplastics pollution started in the 1980's and it is characterized by the terrestrial input. The continental shelf in the SCS is heavily polluted by microplastics. It is further shown that the deep-sea canyons on the continental slope provide important conduits for carrying the microplastics to the deep-sea basin. The turbidity currents play a critical role in the transportation of plastics in the canyon system. This paper reviews recent progresses of studies of plastics and microplastics using manned submersible in the SCS. For the first time, the concept of the deep-sea plastic dump ecosystem is proposed.
[1] Peng X T, Dasgupta S, Zhong G F, et al. Large debris dumps in the northern South China Sea[J]. Marine Pollution Bulletin, 2019, 142:164-168.
[2] Peng X T, Chen M, Chen S, et al. Microplastics contaminate the deepest part of the world's ocean[J]. Geochemical Perspectives Letters, 2018, 9:1-5.
[3] Chen M, Du M, Jin A, et al. Forty-year pollution history of microplastics in the largest marginal sea of the western Pacific[J]. Geochemical Perspectives Letters, 2020, 13:42-47.
