Occurrence And Risk Assessment Of PFASs In The Drinking Water Sources Of Beijing

As emerging persistant organic pollutants(POPs),perfluoroalkyl substances(PFASs)have attracted the worldwide attention due to their persistent,bioaccumulative,toxic and long range transport attributes since 2000.At present,their pollution and transportion in the environment and environmental behavior have become the focus of national attention and research,but study about their occurrence in water and fishes from drinking water sources is still scarce.In present study,the PFASs concentrations in the water and fish samples from these two drinking water sources of Beijing(Miyun Reservoir and Guanting Reservoir)were detected in order to explore the connections between their concentrations and human behavior.Isotope technology was used to identify the trophic level of different species of fish,and then identify the relationship concentrations of PFASs with trophic levels.Besides,the biomagnifications of different PFASs in fish were explored and the risk assessment from PFOS and PFOA contaminants in water and human were estimated.1).Totally 45 samples were collected from Miyun Reservoir(include 7 sites)and Guanting Reservoir(include 8 sites),and PFASs were detected in all water samples.The distribution of PFASs in Miyun Reservoir was uniform,ranging from 5.30 to 8.67 ng/L,with a mean value at 6.70 ng/L.The highest concentration was detected in PFBA(1.51～4.25ng/L),and the second was PFOA(N.D.～2.82 ng/L).The concentrations of PFASs in water from Guanting Reservoir(24.80～142.42 ng/L)were higher than in water from Miyun Reservoir.Higher concentrations were showed in site 4、5 and 6 than site 7 and 8.Comparing with PFASs concentrations from different drinking water sources at home and abroad,Beijing was at a relatively low level.2).Totally 15 samples were collected from Miyun Reservoir and Guanting Reservoir,and PFASs were detected in all fish samples.In Miyun Reservoir,the concentrations of fishes were ranging from 1.70～14.32 ng/g wet weight(ww),with a mean value at 7.05 ng/g ww.The highest concentrations of PFASs was in Pseudohemiculter dispar,followed by Siniperca chuatsi、Erythroculter dabryi、Carassius auratus、Hypophthalmichthys molitrix and Cyprinus carpio.PFOS and long-chain perfluorinated carboxylates(PFCAs)including PFOA,PFNA,PFDA,PFUdA and PFDoA were the most frequently detected PFASs,which were detected in all fish samples,while PFUdA、PFDA、PFBA、PFOS and PFOA were predominant in fish samples.In Guanting Reservoir,the concentrations of fishes were ranging from 2.41～13.13 ng/g ww,with a mean value at 6.98 ng/g ww.PFOS and long-chain perfluorinated carboxylates(PFCAs)including PFOA,PFNA,PFDA,PFUdA and PFDoA were the most frequently detected PFASs which was same to Miyun Reservoir.The highest concentrations of PFASs was in Carassius auratus,then followed by Ophiocephalus argus Cantor、Pseudohemiculter disparHemisalanx prognathous Regan、Pelteobagrus fulvidraco、Erythroculter dabryi、Aristichthys nobilis.Hypophthalmichthys molitrix and Cyprinus carpio.Ingestion and metabolism of fish may dramatically affect the concentrations of PFASs in fish.Overall,PFOS and long chain PFCAs were the main pollutant in fish samples.3).Stable carbon and nitrogen isotopes were detected by Isotope technology,with δ15N ranging from 12.21‰～20.50‰ and δ13C ranging from-29.44‰～24.80‰.Trophic levels of fish in study areas were in the range of 2.30 to 4.52.Because most samples are carnivorous fish and omnivorous fish,the trophic level span is not very big and the levels of most carnivorous fish were higher than the omnivorous one.Biomagnifications(BMFs)of fishes were greater than 1(1.71～4.33)in study area which indicating the biomagnification of PFOS,and the BMFs of PFOS and the enrichment of stable-carbon and nitrogen isotope were basically synchronous.4).Entropy evaluation method and the health risk model recommended by US EPA were used to evaluate the risk of PFOA and PFOS in water and fishes.Compared to Criterion Maximum Concentration(CMC)and criteria continuous concentration(CCC),the concentrations of PFOA and PFOS were at a low risk in drinking water sources from Beijing.Based on statistics of consumption amount of fish in Beijing,the human allowable daily intake(ADI)of PFASs were estimated to be 0.51～1.06 ng/kg/d for PFOS and 0.21～0.44 ng/kg/d for PFOA,respectively,which were below the human tolerable daily intake(TDI)recommended by European Union food safety agency.The current findings indicated that the levels of PFOA and PFOS contamination in water sources of Beijing posed no risk to ecology and human health.