Two decades of spatiotemporal distribution of per- and polyfluoroalkyl substances in the Yangtze River: A meta-analysis.

In this study, we conducted a meta-analysis of data from the past two decades to examine the composition, temporal and spatial distributions, and ecological risks of per- and polyfluoroalkyl substances (PFAS) in the Yangtze River, the longest river in China and the third longest river worldwide. A total of 2248 PFAS concentration records from 206 sampling points were analyzed, revealing that ∑PFAS concentrations in surface water were higher downstream (6.9-3700 ng/L) than midstream (1.8-65 ng/L). Limited data from seven upstream sampling points showed the lowest average concentration of 6.4 ng/L. Since 2016, ether and cyclic PFAS have emerged, with concentrations ranging from 0.05 to 2.1 ng/L, likely due to the transition from perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) to new fluorinated replacements. Among the five most frequently detected PFAS in surface water, perfluorohexanoic acid (PFHxA) and PFOS showed significant increases from 2005 to 2021. Seasonal differences were noted for PFOA and PFOS, with higher levels observed in autumn (Sep-Nov). Risk quotient analysis across three trophic levels indicated that the detected PFAS posed risks below the threshold for high concern. Given the Yangtze River's dense population and numerous fluorinated industries, expanding targeted and non-targeted screening for contaminants beyond the 27 PFAS studied here is critical. This study provides essential insights into the spatial distribution and ecological risks of PFAS contamination along the Yangtze River, highlighting the need for targeted monitoring and regulatory strategies to mitigate PFAS pollution in China and globally.