From greenhouses to open fields: Multidimensional drivers of per- and polyfluoroalkyl substance (PFAS) residues in farmland soils across China.

Despite increasing concerns regarding the adverse impacts of per- and polyfluoroalkyl substances (PFAS) in agricultural soils on ecosystems, the multidimensional drivers and mechanisms of PFAS residues in different farmland types remain poorly understood. Based on a nationwide field survey in China, the concentrations and source contributions of PFAS were compared in greenhouses, film-mulched farmlands, and naked farmlands, revealing their respective driving mechanisms for the first time. The total concentrations of the 24 PFAS were highest in the greenhouse soils. Plastic products (such as agricultural films) and pesticides are potential sources of PFAS in farmland soils. Irrigation water was the major quantified source of PFAS in greenhouse and open-field farmlands (accounting for 20.1% and 31.4%, respectively). The contributions of irrigation water and wet deposition were positively driven by economic and industrial development. Due to data resolution limits, biosolid contributions were likely underestimated in specific regions. Random forest and structural equation modeling were used to evaluate the drivers of PFAS contamination. The model results indicated that socioeconomic and industrial factors and soil properties emerged as key drivers for the three types of farmlands. Agricultural practices significantly influenced the PFAS contamination in greenhouses, whereas open-field farmlands were more susceptible to climatic factors. These findings provide novel insights for sustainable agricultural practices and long-term soil quality management.