The Spatial Distribution And Land-sea Migration Characteristics Of Typical Perfluorinated Compounds In The Water And Sedimentary Environment Of The Yellow River Delta Wetland

Perfluorinated compounds?PFCs?,as a new type of global organic pollutants,have attracted great attention due to their environmental persistence,long-distance migration,biological accumulation and potential toxicity.In this study,the concentrations of 15 PFCs and 3 precursors in the water and sedimentary environment of the Yellow River delta wetland?including water and sediment samples from the original wetland,secondary wetland,river wetland and coastal wetland?and the effluents of sewage treatment plants were measured by the ultra-performance liquid chromatography-tandem mass spectrometry?UPLC-MS/MS?,and analyzed the spatial distribution of them.In addition,this study discussed the conversion potential of PFCs precursor in water and its contribution to pollution,revealed the distribution characteristics of PFCs in various wetland water/sediment systems in the Yellow River delta and the land-sea migration characteristics of PFCs in the Yellow River estuary.The main conclusions were as follows:?1?PFCs pollution was widespread in the water and sedimentary environment of the Yellow River delta wetland.The?PFCs concentration was in the range of 4.38-29.77 ng?L^-1and 4.908-13.536 ng?g^-1 in the water and sedimentary environment of original wetland,respectively.The?PFCs concentration was in the range of 4.38-29.77 ng?L^-1 and 4.908-13.536 ng?g^-1 in the water and sedimentary environment of original wetland.The ?PFCs concentration was in the range of 15.36-40.02 ng?L^-1 and 4.827-14.894 ng?g^-1 in the water and sedimentary environment of secondary wetland,respecti vely.The?PFCs concentration was in the range of 30.54-58.74 ng?L^-1 and 4.296-13.899 ng?g^-1 in the water and sedimentary environment of river wetland,respectively.The?PFCs concentration was in the range of 14.71-62.99 ng?L^-1 and 8.178-14.513 ng?g^-1 in the water and sedimentary environment of coastal wetland,respectively.The?PFCs concentration was in the range of54.44-124.40 ng?L^-1 in the effluents of sewage treatment plants.?2?In terms of space distribution,there were obvious spatial differences within some wetland types.The PFCs concentration in river wetland water increased from upstream to downstream,while the PFCs concentration in river wetland sediments decrease d from upstream to downstream.The PFCs concentration was higher in the southern part of the estuary than in the northern part of the estuary.Industrial and agricultural wastewater,municipal sewage and sewage plant drainage are the main pollution sources of PFCs.?3?After the oxidation treatment,the PFCs concentration obviously increased in all the water samples,which indicated that the precursors were ubiquitous in the water environment.The increased concentration of perfluorocarboxylate?PFCA?with 4-8 carbon chains was significantly higher than that of PFCAs with 9-12 carbon chains.The conversion rate of the precursors in wastewater treatment plant was the lowest,while the increment of PFCAs was the highest,which induced by the precursors'degradation during the sewage treatment process.?4?The distribution coefficient?LogK_D?of PFCs ranged from 1.08 to 4.39 L?kg^-1 in the water and sediment system of the Yellow River delta wetland,which was different among different wetlands.The longer the carbon chain length of PFCs,the worse the hydrophilicity.With the same length of carbon chain,PFCAs was more easily dissolved in water than Perfluorosulfonates?PFSAs?.?5?In the water and sediment of the Yellow River estuary,the flux of?PFCs migrating into the sea was 5.7967 t·a^-1,and the proportion of PFCs exporting to the ocean in the sediments reached 71.21%.PFOS,PFOA and perfluoroundecanoic acid?PFUnDA?were the dominant compounds in the sea migration flux,accounted for 67.8%of the total output.This indicates that the land and sea migration of PFCs requires dynamic support and material foundation.