Per- and polyfluoroalkyl substances in a subtropical river-mangrove estuary-bay system

Mangrove estuaries are one of the most economically valuable and biologically diverse coastal ecosystems. However, knowledge of emerging pollutants in mangrove estuaries is limited. This study provided insight into the PFAS in a river (Zhangjiang River, ZR)-mangrove estuary (Zhangjiang River Estuary, ZRE)-bay (Dongshan Bay, DSB) continuous system in Fujian Province, China. The Sigma(25)PFAS (sum of 25 PFAS) concentrations (0.94 similar to 62.44 ng/L) showed a declining trend from the river to bay. The Zhe-Min Coastal Current (ZMCC) can transport an abundance of PFAS, especially PFOA, from the northern sea to southern bays, which can affect the seasonal distribution of PFAS concentrations in the DSB and result in PFOA/Sigma(25)PFAS with a decreasing trend in the DSB (28.08%), ZRE (21.15%), and ZR (14.13%), respectively. The primary PFAS sources in this area determined by the positive matrix factor model mainly contained the effluent of the wastewater treatment plant neighboring the R2 site, discharge of domestic and production wastewater, irregular emissions of aqueous film-forming foams, and fluorochemistry industry wastewater transmitted from the ZMCC. The PFAS pollution in the mangrove creek was mainly affected by the discharge of domestic and production wastewater and presented a significant point source pollution, especially during the rainy season.

Automated summary

Mangrove estuaries are economically valuable and biologically diverse coastal ecosystems. However, knowledge about emerging pollutants in mangrove estuaries is limited. This study investigated PFAS concentrations in a continuous river-mangrove estuary-bay system in China, revealing a declining trend of PFAS concentrations from the river to the bay. The primary sources of PFAS pollution were identified as wastewater treatment plant effluent, domestic and production wastewater discharge, aqueous film-forming foam emissions, and fluorochemistry industry wastewater. PFAS pollution in the mangrove creek was mainly influenced by domestic and production wastewater discharge, particularly during the rainy season.