Occurrence,Fate And Health Risk Assessment Of Persistent Organic Pollutants In The Mussel Mariculture Area In Yangtze Estuary

Persistent organic pollutants（POPs）were widely distributed in nature and have posed a great threat to human health and the ecological environment.Therefore,the detection technology,pollution monitoring and prevention and control of POPs have been a hot spot for research at home and abroad.Hexachlorocyclohexane（HCHs）,dichlorodiphenyltrichloroethane（DDTs）,chlordane（CHLs）and polychlorinated biphenyls（PCBs）are legacy POPs,which are common pollutants in the environment and are of great concern because they are easily transmitted through the food chain to cause harm to living organisms.Dietary intake was one of the main routes of human exposure to legacy POPs,especially through the ingestion of sentinel organisms such as mussels.Conducting the analysis of HCHs,DDTs,CHLs and PCBs in the medium of the mussel mariculture area in the Yangtze estuary can help to understand the current status of legacy POPs contamination in the area and provide scientific and professional guidance and recommendations for safeguarding the dietary health of local residents.To understand the contamination status of legacy POPs in the mussel mariculture area of the Yangtze estuary,samples of water,mussels and nearby soil were collected in this study,and the content and composition of organochlorine pesticides（OCPs）and polychlorinated biphenyls（PCBs）were determined by GC-MS/MS.The source of contamination were analyzed by principal component and factor analysis,and the risk of food exposure to contaminants in mussels was assessed using the USEPA model.The main findings and conclusions are as follows:（1）The water content of mussel samples ranged from 44.07 to 88.34%,and the fat percentage ranged from 0.06 to 5.29%.OCPs and PCBs were detected in all tissues,with OCPs ranging from 0.40 to 8.39,1.39 to 7.13,0.29 to 7.12,14.8 to 74.4 and 1.69to 3.63 ng·g^-1（wet weight,same as below）in muscle,mantle,gill,gonad and byssus traits,respectively,and PCBs ranging from 6.70 to 101,10.5 to 168,50.1 to 389,278to 1.01×10³,and 21.6 to 101 pg·g^-1,respectively.Compared with other studies,the concentrations of mussel OCPs and PCBs in this study were at moderately low levels.（2）From the average concentration of OCPs,gonad(35.3±20.4 ng·g^-1 wet weight,same as below)>gill（4.30±2.06）>mantle（3.94±2.18）>muscle（3.12±1.78）>byssus traits（2.70±0.77）;from the average concentration of PCBs,gonad(619±291 pg·g^-1 wet weight,same as below)>mantle（141±113）>gill（94.9±56.6）>muscle（81.6±42.2）>byssus traits（49.9±27.6）.The gonads are the main tissues enriched with contaminants,and the byssus traits and gills showed different characteristics from other tissues in terms of accumulation of contaminants,the most important congener of HCHs in gill tissues isα-HCH,while the byssus traits DDT and TC were different from other tissues,may due to more contact with the water column or different life activities.There were various reasons for the different concentrations of legacy POPs in mussel tissues;lipid content,tissue enrichment of the compounds,and other differences can cause inter-tissue differences in legacy POPs in mussels,with lipids being an important factor in this study.（3）The detection of OCPs and PCBs in the water and soil revealed that OCPs and PCBs were widely present in the mussel mariculture area of the Yangtze River estuary with moderate levels of occurrence.The concentrations of HCHs,CHLs,DDTs and PCBs in the water ranged from 0.22 to 1.76,0.01 to 0.02,0.07 to 0.29 and 0.01 to 0.05ng·L^-1,respectively,and those in the soil ranged from 0.18 to 10.4,0.03 to 0.14,2.62to 69.6 and 0.40 to 0.69 ng·g^-1.The ratio method and provenance analysis revealed that the pollutants in the environment mainly originated from historical accumulation,but there were also fresh inputs of pollutants,including chlordane,which may originate from atmospheric deposition,DDT,which may originate from ship paints,etc.,and PCBs,which mostly originate from unintentional emissions.There is a correlation of POPs between media,which implies a similar source.There were correlations between OCPs and PCBs in the media,with many significant positive correlations in HCHs,DDTs and PCBs,which responded to the possibility of similar sources of contaminants.The relationship between mussel tissues and abiotic media can be seen in the principal component analysis,with the highest Log BAF for each compound in the gonads.（4）There were correlations between target compounds in the medium,with many significant positive correlations in HCHs,CHLs,DDTs and PCBs,which responded to the possibility of similar sources of contaminants.The relationship between mussel tissues and non-biological medium can be seen in the principal component analysis,with the highest Log BAF for each compound in the gonads.（4）The health risk of population consumption of mussels in the mariculture area of the Yangtze estuary was investigated by the model of USPEA.It was found that the risk of population mussel consumption to target compounds exposure was extremely low,with no long-term non-carcinogenic or carcinogenic risks.