Coastal Lakes as a Buffer Zone for the Accumulation and Redistribution of Plastic Particles from Continental to Marine Environment: A Case Study of the Dishui Lake in Shanghai, China

Microplastics, as an emerging environmental contaminant, have attracted increasing attention worldwide. Previous studies have addressed this environmental problem in either the marine or continental environment, but ignored the water bodies in between. Coastal lakes are transitional aquatic systems and may play an important role in transport, reworking and redistribution of plastics across catchment scale. Here, we report results of our investigation of plastic pollution in sediment of a coastal lake, the Dishui Lake, in Shanghai, China. The lake is located in coastal Shanghai and connected to the East China Sea via a 7-km long canal. Sediment samples were collected from around the lake and the canal. Plastic particles were detected in the sediment with various shapes, colors and compositions. The total particle count in the canal sediment was orders of magnitude higher than in the lake sediment. Polypropylene was the dominant polymer in the sediment. Our results suggest that coastal lakes can serve as a reworking zone for accumulation and reworkings of plastic particles, and a buffer zone contributing to plastic pollution in the marine environment. This study addresses the most understudied area of plastic pollution, i.e., reworking and redistribution of plastic debris at catchment scale across the marine and continental environment.