Pollution pathways and release estimation of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in central and eastern China

China has gradually become the most important manufacturing and consumption centre for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in the world, and inadvertently become the world's major contamination hotspots. However, a systematic analysis of pollution pathways for PFOS/PFOA into the different environmental compartments and their quantification in China has yet to be carried out. This study focused on PFOS and PFOA release into the environment in the central and eastern region of China, which accounts for the vast majority of national emission. About 80-90% of PFOS/PFOA contamination in the Chinese environment was estimated to come directly from manufacturing and industrial sites mostly via wastewater discharge from these facilities. The other major contamination sources for PFOS were identified as being linked to aqueous fire-fighting foams (AFFFs), and pesticides including sulfluramid. For PFOA, following some way behind industrial wastewater, were industrial exhaust gas, domestic wastewater and landfill leachate as contamination sources. For surface water contamination, the major pollution contributors after industrial wastewater were AFFF spill runoff for PFOS, and domestic wastewater and precipitation-runoff for PFOA. The majority of PFOS that contaminated soil was considered to be linked with infiltration of AFFF and pesticides, while most PFOA in soil was attributed to atmospheric deposition and landfill leachate. Where groundwater had become contaminated, surface water seepage was estimated to contribute about 50% of PFOS and 40% of PFOA while the remainder was mostly derived from soil leaching. A review of the available monitoring data for PFOS/PFOA in the literature supported the view that industrial wastewater, landfill leachate and AFFF application were the dominant sources. Higher concentrations of PFOA than PFOS found in precipitation also corroborated the prediction of more PFOA release into air. To reduce PFOS/PFOA contamination of the Chinese environment the focus for control should be on industrial wastewater emissions.