Microplastic occurrence and hydrodynamic-sedimentary driving effects in the Bohai Strait region of China

The ubiquity of microplastics in oceans has led to an increased interest in microplastics in society. The Bohai Strait is in a key position in the Yellow and Bohai Seas and plays a key role in the exchange of materials and environmental changes in these waters. In this study, seawater, surface sediments, and column sediments, were collected from the Bohai Strait region. Among all seawater samples, the abundance of microplastics in the Bohai Strait region ranged between 0.38 and 3.20 items/L, and that of microplastics in surface sediments was between 15.80 and 94.41 items/kg d.w.. The average microplastics abundance in columnar sediments was 72.62 ± 29.86 items/kg d.w., which provided key information on the spatial distribution of microplastics and sedimentation phenomena in the Bohai Strait region. The abundance of microplastics was higher in regions where currents flowed more slowly, which suggests that ocean currents exert a crucial effect on microplastic distribution. In addition, the abundance of microplastics in sediments showed a close relation to the deposition rate, which implies that the deposition rate contribute to the deposition process of microplastics on the seafloor. The type of microplastics in seawater influences the kind of microplastics in sediments, which further emphasizes the importance of microplastics in seawater during microplastic transport and the deposition process. The results of this research contribute to the in-depth understanding of the behavior and propagation pathways of microplastics in oceans and provide a valuable reference for the reduction of microplastic pollution.