An overview of microplastic pollution in the environment over the megacity of Shanghai during 2013-2022

Microplastics (MPs) are emerging pollutants that have been globally found in the environment, and have become a focus of intensive management for the Shanghai government in China. Although there are several studies reporting the abundance of microplastics (MPs) in different matrices in Shanghai city, the general data are still limited. This work comprehensively reviews microplastic (MP) pollution in the water, sediment, atmosphere, and soil of Shanghai during 2013-2022. A summary of characteristics such as the abundance, shape, and polymer composition of MPs is presented. Additionally, the pollution trends, traceability, and ecological risks of MPs are analyzed and evaluated. Based on the analytical results, we find that the inland water in Shanghai city is the most contaminated with the highest abundance of MPs at 14.76 x 103 particles/m3 on average, while the abundances of MPs in the external water, inland sediment, external sediment, indoor atmosphere, outdoor atmosphere, inland soil, and external soil are 2.78 x 103 particles/m3, 0.80 x 103 particles/kg, 1.37 x 103 particles/kg, 0.03 x 103 particles/m3, 0.08 x 103 particles/m3, 0.27 x 103 particles/kg, and 0.18 x 103 particles/kg, respectively. Polyethylene and polypropylene are the top two detected polymer compositions of MPs. Results of ecological risk assessment using risk index and pollution load index models indicate that the risks of MPs in the water and sediment of the Yangtze Estuary are high. It is noteworthy that the abundances of MPs at the junction site of Suzhou Creek and the Huangpu River as well as in the Yangtze Estuary exhibited an increasing trend between 2017 and 2019. This work contributes to a comprehensive overview of MPs in the environment of Shanghai city during 2013-2022 and provides important data for local governments to develop urgent strategies for the management of MP pollution. However, more investigations are increasingly needed for better understand the production, migration, ecological risk, and management of MPs in the environment of Shanghai city.