Distribution patterns and influencing factors of PFAS in soils: A meta-analysis

Due to their high emission and persistence, per- and polyfluoroalkyl substances (PFAS) are ubiquitously distributed in the environment, with soil increasingly serving as a major medium for PFAS. Currently, research on the environmental distribution of PFAS primarily focuses on surface water and groundwater, while systematic global investigations into PFAS distribution in soil remain limited. In this study, we collected PFAS concentrations data from literatures published in 2006-2024 and Map of Forever Pollution in Europe. PFAS concentrations in global soil exhibited spatial heterogeneity (n.d. - 1838 ng/g), with relatively higher levels in Europe, the U.S., and Eastern China. For temporal trend, PFOA, PFHxS, and PFOS generally decreased in the time span of 2005-2019, but the declining trend was relatively sharper in the U.S. compared with China. The meta-analysis indicated that soil properties, including soil texture, organic carbon content, total nitrogen content, and pH, as well as socioeconomic levels such as GDP per capita, per capita consumption expenditure, population density, and industrial proportions, were key factors affecting the distribution of PFAS in soil. Emerging PFAS showed regional differences in detection frequencies, with HFPO-DA (63.84 %-100 %) and 6:2 Cl-PFESA (69.38 %-100 %) predominating in China, 6:2 FTAB (78 %) in the U.S, PreFOSs and PAPs (90 %-100 %) in Europe. This study provides information on the current status of PFAS pollution in soil and key factors affecting its regional distribution, which is beneficial for strengthening the investigation of PFAS soil pollution in areas with less research and developing control and management strategies for high pollution areas.