|Other Abstract||PFASs are widely used in industrial and domestic products owing to their unique physical and chemical properties. At present, PFASs are ubiquitously presented in the atmosphere, water, sediments, organisms and other environmental media all over the world. They can be bioaccumulated and biomagnified through the food chain, posing a great threat to the ecosystem and human health, and hence attracting international attention. As PFOS and PFOA have been included in the Stockholm Convention, the production and use of short-chain PFASs and novel PFASs have gradually increased, and resulted they been frequently detected in the environment, becoming a new research hotspot.
In this study, solid phase extraction (SPE) enrichment combined with ultra-high performance liquid chromatography/mass spectrometry (UPLC-MS/MS) detection methods were used to analyze the distribution characteristics of 21 PFASs in the river-estuary environment. This research includes two parts: 1. To screen the PFAS contamination status and distribution characteristics by analysis riverine surface sediments surrounding three different fluorine industrial parks, i.e., Xihe River in Liaoning province, Xiaoqing River in Shandong province, and Yangtze River in Jiangsu Province; 2. Taking the most polluted Xiaoqing River among the three regions as a case study, to analyze the distribution characteristics of PFASs and the partition coefficients of PFASs between soluble phase/suspended particulate matter (SPM) in the entire river basin. The specific conclusions are as follows:
1. The concentration and composition of PFASs varied largely in the surface sediments among the three rivers near the fluorine industrial parks. Xiaoqing River showed the highest PFASs levels, followed by the Xihe River, and finally the Yangtze River. The dominant compounds were PFOA and HFPO-DA in the Xiaoqing River, PFBS and HFPO-DA in the Xihe Rvier, and PFTeDA and 6:2 FTS in the Yangtze River, respectively. This is mainly attributed to the capacities, technical processes, and production mode in different industrial parks.
The correlation between PFASs and physical and chemical properties of the sediments were complicated among the three regions, indicating that the transfer and enrichment processes of PFASs in the sediments were affected by many factors.
2. Extremely high levels of PFASs were detected in the surface water and SPM of Xiaoqing River. The concentration of PFASs in the surface waters of Xiaoqing River ranges from 94.0 to 444,000 ng/L, and the dominant pollutants are PFOA, PFHpA and HFPO-TA. In SPM, the concentration of PFASs ranges from 34.6 to 94,900 ng/g dw, and HFPO-TA and PFOA are the main pollutants. The concentration of PFASs rose sharply at station X10 on the Dongzhulong tributary, which locates downstream of the fluoride industrial park, indicating that point source emissions are the main cause of PFASs pollution and have an impact on the PFASs pollution of the main stream of the Xiaoqing River. The partition coefficients of PFASs between the SPM and soluble phase were related to the lengths of the carbon chain and the physicochemical properties of the pollutants. Long-chain PFCAs and PFSAs were prone to adsorb to SPM. In addition, the increase in the concentration of SPM in water will affect the distribution behavior of PFASs.
By comparing the concentration and composition of PFASs in the surface sediments of the rivers surrounding different industrial parks, it is found that the factory capacities, chemical processes and production mode of different industrial parks may have different effects on the surrounding environmental media. In different regions, the impact on PFASs of the nature of the compound and the physical and chemical is also different. Among the three regions, Xiaoqing River showed the most serious PFASs contamination, and the concentration of PFASs in the water is directly affected by point source emissions. The distribution of PFASs between the SPM-water phases is affected by the nature of the compound and the concentration of SPM in the water. Therefore, in the follow-up study of the distribution, allocation, migration and transformation of PFASs in the water environment, it is necessary to comprehensively consider factors such as point source characteristics, compound properties, and physical and chemical properties of environmental media, in order to make a more comprehensive and detailed analysis of PFASs in the environment.|