Levels, distributions, and sources of legacy and novel per- and perfluoroalkyl substances (PFAS) in the topsoil of Tianjin, China

Soil is a major sink for per- and perfluoroalkyl substances (PFAS), wherein PFAS may be transferred through the food chain to predators at upper trophic levels, which poses a threat to human health. Herein, the concentrations and distributions of legacy and novel PFAS in topsoil samples from different functional areas in Tianjin were comprehensively investigated. Seventeen PFAS congeners were identified, with concentrations ranging from 0.21 ng/g to 5.35 ng/g, with a mean concentration of 1.25 ng/g. The main PFAS in the topsoil was perfluorooctanoic acid (PFOA). 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA; C8) were the major sources (43.4%), followed by food packaging as well as coating materials (25.5%). In addition, Spearman correlation analysis and the structural equation model showed that population density significantly impacted the PFAS distribution in the topsoil of Tianjin.