First Nationwide Survey of Legacy and Emerging Per- and Polyfluoroalkyl Substances in Japanese Rivers: Spatial Distribution and Riverine Loads

Abstract

Abstract

In Japan, river water quality monitoring for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) was initiated by the government in 2020. However, per- and polyfluoroalkyl substance (PFAS) precursors and alternative PFAS have not been investigated, and their occurrence remains poorly understood. Therefore, a nationwide survey of 30 legacy and emerging PFAS, based on ISO 21675, was conducted at 39 sites across rivers in Japan. Twenty PFAS were detected in Japanese rivers, with ∑PFAS concentrations ranging from <0.50 to 140 ng L −1 . The mean ∑PFAS value was 18 ng L −1 , which is presumed to reflect the average PFAS concentration in Japanese rivers without specific PFAS pollution sources. The detection frequency exceeded 50% for short-chain C 4 perfluoroalkyl sulfonic acids and perfluoroalkyl carboxylic acids. Hexafluoropropylene oxide dimer acid (HFPO-DA) was detected more frequently than other emerging PFAS. Significant differences were found among districts (Kruskal–Wallis test, p < 0.001), with ΣPFAS concentrations in the Kinki district being significantly higher than those in other districts, excluding Kanto (Dunn test, p < 0.05). A weak correlation was observed between river basin population density and ΣPFAS concentrations, indicating that urban activities may be a primary source of PFAS pollution. The estimated ΣPFAS load in the surveyed Japanese rivers was 865 kg per year. These findings provide valuable insights into the current PFAS status in Japanese rivers and offer a scientific basis for future water quality management and PFAS regulations in Japan.