Pollution Characteristics And Risk Assessment Of Typical POPs In Drinking Water Sources In The Middle And Lower Reaches Of The Yangtze River

The Yangtze River is an important source of drinking water for residents along the coast,and it is one of the most economically dense economic zones and watersheds with the most prominent water environment problems in China,except for coastal open areas.With the development of the local economy and the improvement of people's living standards,trace amounts of persistent organic matter(POPs)in water sources have become a concern of the people.POPs are a class of persistent,highly toxic,difficult-to-degrade and long-distance transmission,which are common in the environment.At present,POPs in sediments have become a source of pollution in water sources.In this study,water samples and sediments were collected at the water intakes of drinking water sources in the middle and lower reaches of the Yangtze River.Polycyclic aromatic hydrocarbons(PAHs),organic chlorine(PAHs),OCPs)and polychlorinated biphenyls(PCBs)pollution characteristics and risk assessment;provide scientific basis for policy formulation to protect and improve the Yangtze River ecological environment and ensure the safety of drinking water.In this paper,the method of isotope dilution HRGC/HRMS established in the laboratory is used to analyze the typical persistent organic pollutants.After the initial precision and recovery of the method reached the quality control requirements,PCBs,OCPs,PAHs in water samples,sediments and suspended particles were analyzed.The results show:PCBs in water,sediment and suspended particulates is 0.04 – 11.0 ng· L-1(median 2.18 ng· L-1,detection rate is 100%),0.33–69 ng·g-1 dry Weight(2.56 ng·g-1,100%),0.72–153 ng· L-1(8.41 ng· L-1,100%).PCB28 and PCB118 showed higher detection rates of PCBs;PCB118 was detected in three phases in dioxin-like PCBs.The PCBs in water are mainly dichloro and tetrachloro PCBs;the sediments are mainly dichloro to hexachloro PCBs;the suspended particles are mainly tetrachloro PCBs.Analysis of its migration and transformation showed that PCBs in the three media did not reach equilibrium.Ecological risk assessment showed that PCBs in water sources in the middle and lower reaches of the Yangtze River had no carcinogenic and non-carcinogenic risks,and the sediments had potential ecological risks.OCPs in water,sediment and suspended particulates are 0.31–5.39 ng· L-1(1.99 ng· L-1,100%),0.52–93.0 ng·g-1 dry weight(2.73 ng·g-1,100%),0.23–11.4 ng· L-1(0.63 ng· L-1,100%).Comparing this area with other watersheds at home and abroad shows that the pollution of OCPs in water sources in the middle and lower reaches of the Yangtze River is at a moderate level.The main pollutions in water and sediment are ?-HCH and ?-HCH,but the detection rate of HCHs in suspended particles is low;HCHs,DDTs,and Pe CB in three phases do not reach equilibrium in the three media.Organochlorine pesticides in water have no carcinogenic or non-carcinogenic risks,and the ecological risks of organochlorine pesticides in sediments are at a low level.PAHs at concentrations of 36.7-151 ng· L-1(82.4 ng· L-1,100%)and 189-7956 ng·g-1 dry weight(761 ng·g-1,100%).Compared with other regions,the level of PAHs pollution in this region is at a moderate level.The 16 types of PAHs differ greatly in water bodies and sediments.The tricyclic and tetracyclic PAHs are the main types of water,and the tetracyclic PAHs are the main types of sediments.The source of pollution is analyzed.The main source of pollution in the water body is the combustion of coal and charcoal,while the main source in the sediment is the pyrolysis of petroleum products.There is no carcinogenic or non-carcinogenic risk in the source water of the lower reaches of the Yangtze River.Polycyclic aromatic hydrocarbons in the sediments have potential ecological risks.