Pollution Characteristics Of Per-and Polyfluoroalkyl Substances In A Fluorochemical Manufactory And Surrounding Water Environment

Perfluorooctane sulfonate(PFOS)and perfluorooctanoic acid(PFOA)with eight carbon chains,which are persistent and difficult to degrade in the environment.They have high accumulation and toxicity in organisms,and have been included in the list of persistent organic pollutants(POPs).Governments around the world have introduced a series of relevant management measures and legal policies to control the production and use of PFOS and PFOA.However,in order to meet industrial demand,some PFAS substitutes are still being developed and put into use.The widespread use of these substitute products has led to the continuous emergence of novel PFAS in the environment.Although some studies have identified various novel PFAS in aquatic environments based on non target recognition strategies using high-resolution mass spectrometry,their sources are still unclear.This study used high-performance liquid chromatography-high-resolution mass spectrometry and non-target screening technology to study the fingerprints of traditional and novel PFAS in wastewater and sewage treatment systems of various workshops in a fluorochemical manufactory,and to explore the pollution levels and sources of novel PFAS in the upstream and downstream rivers and surrounding tap water of fluorochemical manufactory;Using the fluorochemical manufactory pollution fingerprints,further trace the source of novel PFAS in Tangshan Lake which is a typical PFAS polluted water area.The main research findings are divided into three parts:Based on the analysis of PFAS by lliquid chromatography-electrospray ionization tandem mass-spectrometry(HPLC ESI MS/MS),using high reselution mass spectrometry to optimize the conditions of chromatography and mass spectrometry.37 kinds of four classes were completed.The compounds have good separation,with a minimum detection limit of0.1 ng/m L and a linear range of 1-20 ng/m L.We investigated the extraction and purification performance of various solid phase extraction(WAX,HLB,and ENV+)columns,and found that most of the long chain PFCA and PFSA spiked recoveries performed well in all three small columns(83%～112%),while HLB small columns performed poorly in long chain alkyl acids and sulfonamide compounds.ENV+columns exhibit poor performance in short chain PFAS and some PFOS precursor substances(Pre FOSs).The WAX column performs well on most compounds,with recovery rates ranging from 80% to 118%.Finally,WAX column was selected for enrichment analysis of various PFAS in water samples.The detection limit,repeatability,blank matrix spiked recovery rate and other indicators of the method meet the analysis of actual samples.Collecting samples of wastewater from the fluorochemical manufactory,wastewater from various stages of the sewage treatment plant,upstream and downstream river water from the fluorochemical manufactory,and surrounding tap water.Using non-target screening methods to qualitatively and quantitatively analyze PFAS in the water samples.The results showed that 73 PFAS from 16 classes were detected in the wastewater from the manufactory workshop and various links of the sewage treatment plant.56 PFAS from 14 classes were detected in the upstream river of the factory and 76 PFAS from 17 classes were detected in the downstream river.54 PFAS from 12 classes were detected in tap water.Analysis of the perfluorinated products produced by the factory revealed that some products contained a small amount of impurities from other products,ranging from 0.20% to 18.5%.By comparing the detection of PFAS in wastewater and sewage,it was found that a large number of carboxylic acid by-products,including C3-C7 perfluorocarbonic acid and hydrogenated substituted PFCA(Hn PFCA).The wastewater produced more sulfonic acid compounds after treating the sewage,including perfluoroether sulfonic acid,perfluorosulfonic acid,and hydrosubstituted PFSA(Hn PFSA).The spatial distribution results of the upstream and downstream river water indicated that the discharge of the factory effluent significantly affects the downstream river water.PFAS in the upstream river water is mainly composed of PFBA and perfluorohexanesulfonic acid(PFBS).The type and concentrations of PFAS in the downstream river have significantly increased,such as PFBS,perfluorohexanesulfonic acid(PFHx S),PFSCA,and Hn PFSA.In addition,PFAS in the surrounding tap water is mainly composed of PFBA,PFBS,and PFOS,but the proportion of main pollutants varies at each point,indicating that the pollution sources are different.Moreover,the PFAS pollution fingerprints in some tap water are similar to those of river water contaminated by the manufactory,suggesting that the tap water in this area may have been affected by the manufactory.However,there are still other pollution sources that require further investigation and research.A typical PFAS polluted water area,Tangxun Lake,was selected to analyze and study its PFAS pollution source using the fluorochemical manufactory pollution fingerprints.18 surface water samples from the Tangxun Lake inlet and lake area was collected and analyzed by using non-target screening methods The results showed that 57 PFAS from 13 classes were detected in the water samples of Tangshan Lake,among which the target PFAS mainly includes PFBS,PFBA,PFOS,and PFOA,with concentrations accounting for 15% to 57%,10% to 26%,7% to 20%,and 1% to 10%,respectively.The total concentration of non-target compounds is equivalent to the total concentration of target compounds,mainly composed of Hn-PFCA,PFPr A,and perfluorodicarboxylic acid(PFDCA),with concentrations accounting for 43% to 85%,8% to 36%,and 2% to 18%,respectively.Compared with studies conducted ten years ago,the concentrations of PFBS and PFBA in water samples have significantly decreased,with PFBS concentrations decreasing from 3720 ng/L to 465 ng/L and PFBA concentrations decreasing from 4580 ng/L to 137 ng/L.Compared with previous studies on the Tangxun Lake water area,this study screened new PFAS species that were different from the past and had a higher content.The PFAS in the water sample of Tangshan Lake is mainly composed of carboxylic acid compounds,which have similar characteristics to the by-products of the electrochemical fluorination factory.It is speculated that there is an industrial pollution source upstream.Further research are needed on the upstream sewage outlets and surrounding factories.