A coupled hydrological multimedia model used to simulate PFASs transport and fate in the river network of megacity Shanghai

Per- and polyfluoroalkyl substances (PFASs), as the “Forever Chemicals”, are ubiquitous in environments, showing serious threaten to ecological safety and human health. Urban river networks are critical systems for PFASs behaviors. However, the mechanisms of discharge and multimedia transports of PFASs remain unclear, which hinder effective management in megacity. In this study, based on the field measurement and discharge estimation, we developed a dynamic model accounting for the hydrology and multimedia processes to simulate the transport and fate of PFASs in river networks of Shanghai. Results showed that PFASs were widely detected in the river networks. The discharge of representative PFASs (PFOA and PFOS) increased from 1990 to 2022, and high concentrations were observed at upstream basin, local industrial zones and intense human activities areas. The coupled model revealed dynamic distribution of PFOA and PFOS in the water and sediment. The concentration in water and sediment showed an upward trend before 2005 and remained stable until 2022. Land use types, population densities, GDP values and water flow were proven to be significant factors and should be considered when constructing the model. The research provides new insights for accurate simulation of urban multi-media environmental processes and a scientific basis for PFASs management and control in megacity.