Occurrence Of Polycyclic Aromatic Hydrocarbons(PAHs) In Water Environment From Hangbu-Fengle River:Pollution Characteristics,Potential Source And Risk Assessment

Due to its ability of long-distance migration,PAHs,a kind of typical organic pollutant with durability,commonly exists in regional and global environment media of a variety:atmosphere,soil,water,etc.It is also featured by mutagenesis,carcinogenesis,teratoeenesis,environmental persistence and biocondensation.Now researchers many countries pay high attention to environmental problems caused by PAHs.Hangbu-Fengle River is the principal tributary of Chaohu and its water quality is favorable in general.But in recent years the quality is on the downgrade since the river has to receive more and-more industrial-effluent,domestic sewage and other pollutants discharged by fuel consumption.For the sake of studying the situation of PAHs in Hangbu-Fengle watershed,we have collected surface water and surface sediment samples in 12 spots and anodonta woodiana samples in 8 spots along the river.For the water samples,they were concentrated with SPE?solid phase extraction?while the other samples were extracted with ASE?accelerated solvent extractor?after cryodesiccation.The extract liquid was then condensed and purified.After that GC-MS?gas chromatograph-mass spectrometer?analyzed the liquid to determine the situation of 16 kinds of precedent-controlled PAHs in it,including-content,The-distribution characteristics and possible sources of PAHs were discussed,and possiable ecological risk was assessed.The purpose is to provide base data and scientific evidence for the regulation and management of organic pollutants in Chaohu and its tributaries.Reaseach contents and conclusions results were surmmarized as following:In the present study,the concentrations of 16 types of PAHs in surface sediments of 12 sites from Hangbu-Fengle River were determined.Sixteen types PAHs all were detected in sediment samples.The concentration of PAHs varied from 71.3±15 to 3372±402 ng g'1 dry weight?dw?and the average was 938 ng·g^-1?dw?,which suggested pollution status was in the medium level compared with other significant rivers and lakes in China.The spectrum of PAHs showed that 4 and 5 ring PAHs were predominant,which accounted for 81%?PAHs.DBA was the most abundant PAH compound in the sediments,with the average concentration of 254 ng·g^-1?dw?.There was a linear correlation between ?PAHs.concentrations and sediment TOC contents.Using characteristic ratio method and principal component analysis,the potential sources of PAHs were analyzed.Results suggested the PAHs in sediments from Hangbu-Fengle River were mainly from coal and wood combustions,gasoline and diesel emissions.The ecological risk and carcinogenic risk of PAHs in sediments from Hangbu-Fengle River were assessed by sediment quality guideline and the total toxic benzo[a]pyrene equivalent?TEQBaP?.Results demonstrated that some of PAHs exceeded ERL several sample sites,which has the potential ecological risk.The calculated TEQBaP were 343 ng·g^-1,suggesting the high potential risk from the sediments.In the present study,the concentration of 16 types of prior controlled polycyclic aromatic hydrocarbons?PAHs?in Anodonta woodiana from Hangbu-Fengle River were determined.In addition,the potential sources of PAHs were discussed and its ecological risk was assessed.It was found that 16 types PAHs all were detected in Anodonta woodiana samples.The concentration of PAHs varied from 707.7 ng·g^-1 to 1614.5 ng·g^-1 dry weight?dw?and the average concentration was 1110.8±254.1 ng·g^-1.Indeno[1,2,3-cd]pyrene was the most abundant PAH compound in Anodonta woodiana,with the average concentration of 209.7±92.1 ng·g^-1,which accounted for 18.9%?PAHs.While the concentration of Acenaphthylene was the lowest,with the average concentration of 9.3±0.7 ng·g^-1,which merely accounted for 0.8%?PAHs.The rings component of PAHs showed that 2?3,4 and 5?6 rings PAHs accounted for 29.8±11.4%,19.5±3.7%,50.7±10.9%?PAHs,respectively,suggesting that high ring PAHs were the dominant congeners.The characteristic ratio was applied to analysis the potential sources of PAHs,and results displayed that the PAHs in Anodonta woodiana from Hangbu-Fengle River were mainly from coal and wood combustions and partial pertroleum pollution.The ecological risk and carcinogenic risk of PAHs were assessed by single pollution index method and the total toxic benzo[a]pyrene equivalent?TEQBaP?.Single pollution index results demonstrated that Benzo[a]pyrene out of limits severely,the maximum value were 3.03 times more than limits.The calculated TEQBaP values were ranged from 53.5 ng g^-1 to 414.5 ng·g^-1,indicated high potential carcinogenic risk in Anodonta woodiana from Hangbu-Fengle River.The conventional indexes of water quality in Hangbu-Fengle River watershed are normal except the indexes of COD of spot No.5 and No.10 are higher.In this watershed,the content of PAHs ranges from 69 ng·L^-1 to 3349 ng·L^-1 with an average of 952 ng L'1,which is at a slight pollution level compared with other watersheds at home with ecological risk to a certain extent.The content of PAHs is highest in midstream which is manufacturing districts and living districts.The content is lower near the entrance to Chaohu Lake and it is lowest in upstream because human activities can make huge influence.PAHs with different cycles have different solubility in water and residents in different district take different activities.Maybe that is why the PAHs found in Hangbu-Fengle River are mainly of two or three cycles in which Nap takes the first place in content.The ecological risk entropy method the results show that the high risk entropy of Nap was greater than 1,serious pollution,Acy,Ace,Flu,Phe,Ant,Fla,Pyr,BaA and BkF low risk entropy is greater than 1,the PAHs in the study area of memory in certain ecological risks.Overall,Hangbu-Fengle River water PAHs ecological risk at a high level,We should pay enough attention to it.