Mapping Legacy and Emerging PFAS in China’s Staple Crop Farmlands: Occurrence, Source Tracing, and Risk Prioritization from Paired Soil–Crops

Per- and polyfluoroalkyl substances (PFAS) are increasingly detected in agricultural environments, yet national-scale data on PFAS contamination in paired food crops and soils remain scarce. This study presents the first nationwide investigation of legacy and emerging PFAS in paired soil and grain samples (n = 160) from 11 provinces representing China's major rice, wheat, and maize producing regions. PFAS were ubiquitously found in soils (median: 4.96 ng/g; range: 2.28-33.5 ng/g) and grains (7.74 ng/g; 2.40-25.3 ng/g), with short-chain perfluoroalkyl carboxylic acids being the dominant class. The emerging-to-legacy PFAS ratio was 2.16 in soils and 4.26 in grains, and crop PFAS levels were 1.5 times higher than those in corresponding soils, indicating the greater propensity of emerging PFAS to be transported into crops. Paddy soils exhibited significantly higher PFAS concentrations than dryland soils (p < 0.05), likely due to irrigation-driven accumulation. In addition, intensive anthropogenic activities were found positively related to PFAS concentrations in soils (r = 0.54, p < 0.05). Positive Matrix Factorization (PMF) analysis attributed PFAS sources primarily to food packaging, textile processing, and fluorochemical industries. Risk prioritization based on the ToxPi framework highlighted PFPeA, PFOA, PFOS, and HFPO-DA as priority compounds of concern. This study provides essential baseline data on PFAS contamination in Chinese farmland and paired staple crops, supporting regulatory oversight of both legacy and emerging PFAS in agricultural systems.