PFASs in China's soils: Temporal declines in legacy compounds mask rising threats from substitutes

As a global hotspot for per- and polyfluoroalkyl substances (PFASs) production and use, China faces growing concerns over soil contamination. Understanding the current contamination status can provide a critical reference for assessing the effectiveness of ongoing regulatory efforts. In this study, we synthesized a total of 73 field-based investigations on surface soil PFASs in China, published between 2010 and 2026, to examine their spatiotemporal occurrence patterns using meta-analysis. The results showed that PFOA, PFOS, and PFBA exhibited the highest nationwide occurrence levels, with weighted mean concentrations of 1.217, 0.497, and 0.485 ng/g, respectively. In contrast, 6:2 Cl-PFESA and HFPO-DA showed relatively low nationwide levels but were more sensitive to industrial soils and point-source influences. Spatially, East China, Central China, and Southwest China exhibited relatively elevated PFAS levels. East China was characterized by regional accumulation and multi-source inputs, whereas high concentrations in parts of Central and Southwest China were more strongly influenced by point-source activities. Over the past 17 years, PFOS and PFNA showed weak declining trends, decreasing by 11.0% and 7.4%, respectively, while PFOA exhibited a delayed decline, likely reflecting the influence of the Stockholm Convention. In contrast, 6:2 Cl-PFESA and HFPO-DA showed marked increasing trends. Geodetector analysis indicated that the spatial heterogeneity of soil PFASs was jointly driven by economic and climatic conditions. Compared with tolerable daily intake thresholds, PFOA and HFPO-DA presented relatively higher potential health risks. This study provided insights into PFAS pollution patterns in Chinese soils and supports improved management and safer chemical substitution strategies.