Spatial distribution, sources and risk assessment of perfluoroalkyl substances in surface soils of a representative densely urbanized and industrialized city of China
By Tang, Li, Xuran Liu, Guojing Yang, Jingfen Xia, Ni Zhang, Dongbo Wang, Hengwei Deng, Min Mao, Xiaoming Li, and Bing-Jie Ni
December 1, 2020
As a representative densely urbanized and industrialized city of China, Ningbo has experienced extremely rapid development, with a wide variety of chemical, electronic, pharmaceutical, and paper manufacturing industries. However, limited data and researches are available regarding the levels and profiles of perfluoroalkyl substances (PFASs) in surface soils of Ningbo. The present study was launched to address the knowledge gap through analyzing 27 sites in five functional regions for 9 PFASs types. Results showed that concentrations of the total PFASs (∑PFASs) ranged from 0.63 to 25.6 ng·g−1, with an average of 10.1 ng·g−1. The concentrations of ∑PFASs in different functional regions were in the order of landfill sites > industrial areas > farmlands > residential communities > animal farms. Correlation analyses between soil physicochemical properties and PFASs content revealed that concentrations of ∑PFASs were negatively correlated with soil pH but positively correlated with soil organic matter. Principal component analysis indicated that fluorochemical industrial discharge, daily life discharge, atmospheric precipitation, and electrochemical fluorination process dominated factor loadings. In addition, the ecological risk assessment based on the risk quotient demonstrated that although the risk of PFOA contamination in landfill sites was highest, there are no risk of PFOA and PFOS contamination in the surface soil environment, but needs more supervision for the neighborhood of landfill sites to avoid additional risk. This work provides new data on the different PFAS profiles in soils impacted by different contamination sources within a densely urbanized and industrialized area, and the results obtained should be useful for delineating priority sites for remediation and restauration of polluted soils.
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