Study On Occurrence Characteristics And Risk Assessment Of PFASs In Chaohu Lake

Perfluoroalkyl substances(PFASs)are a new type of persistent organic pollutants with strong bioaccumulation,distance migration,environmental persistence and potential toxicity,which exist widely in the world.Domestic water,soil,sediment and other environmental media can be detected.As a new pollutant with both reproductive and developmental toxicity,it is of great significance to explore the component concentration and health risk of PFASs in the environment.In this study,60 water samples,12 fish samples and 4 submerged plant samples were collected from Chaohu Lake,and the contents of 17 PFASs in water samples and fish samples were determined.The PFOS stress test was carried out on 2 submerged plants.The results showed that:(1)PFBA and PFBS in Chaohu Lake water have replaced PFOA and PFOS as the main components of PFASs,it shows that the implementation of Stockholm Convention in Chaohu Lake region has a significant effect on promoting the replacement of long-chain PFASs;(2)Compared with the 2010 s,the total concentration of PFASs in Chaohu Lake decreased by41.7%,and the water phase was not the final trend of PFASs;(3)The distribution of PFASs in Chaohu Lake showed a trend of high distribution in the east and high distribution in the west.PFASs mainly entered Chaohu Lake through rivers,of which Pai River was the main input source.The highest concentration of PFASs was 173.26ng/L in Pai River estuary;(4)Systematic cluster analysis showed that PFOA and PFBS were congener within the 5-step iteration range,and the PFBS content was the lowest in the mouth of the Diangbu River and the South Feihe River,which was 11.67ng/L.The spatial distribution characteristics of PFBS and PFOA were identical,indicating that PFBS and PFOA had certain homology near the mouth of the Diangbu River and the South Feihe River.The replacement of PFOA in the region is relatively lagging behind or a large amount of degradation of PFOA precursor in domestic sewage;(5)The concentration of PFOA near Baishitian River in Chaohu Lake was 17.26 ng/L,decomposition of PFOA precursors by sewage treatment plants may be an important reason for the high concentration of PFOA in this area;(6)PFOS enrichment in Channa argus was very serious among all kinds of fish in Chaohu Lake,although the human daily intake of Channa argus based on PFOS only accounted for 22.37% of the daily intake threshold,due to the important role of Channa argus in the diet of Chinese patients and pregnant women,we should pay more attention to the toxicity risk of PFOS;(7)Compared with Myriophyllum spicatum and Vallisneria natans,Ceratophyllum demersum and Hydrilla verticillate were more sensitive to PFOS stress,in the same concentration of PFOS stress,the changes of physiological and biochemical indexes of the two submerged plants were more drastic;(8)The changes of MDA content in the two plants were different under PFOS stress,and the different trends indicated that the two plants had different effects on PFOS stress;(9)The results of PFOS stress experiment showed that 75mg/L PFOS could produce oxidative stress on submerged plants,POD、SOD、CAT constitute the antioxidant system in plants,they play a protective role in plant growth and development.