Study On Distribution Characteristic, Source And Risk Assessment Of OCPs, PAHs And PFCs In Typical Regions Of Hubei, China

Organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs) and perfluorinated compounds (PFCs) are three kinds of typical persistent organic pollutants (POPs) which are ubiquitous in the environment and have caused wide concern in the world. Their existences have posed a threat to the food safety, ecological environment and human health, in terms of their persistence, bioaccumulation and toxicities. Hubei province is a fulcrum and the center of China’s "rise of central China" strategy. In recent years, with the rapid development of Hubei’s urbanization and industrialization, more and more POPs emit into the environment. Thus, the food safety and environmental pollution problems are becoming more and more serious in Hubei province.In this study, the typical regions (Wuhan, Yichang, Xiangyang and Jingzhou) and the key water regions (Danjiangkou reservoir and the Hanjiang River) of Hubei were selected for the main research areas. The spatial distribution characteristics and sources of OCPs, PAHs and PFCs were analyzed in fish, soils and sediments from these specific regions of Hubei. Potential ecological risks and human health risks were assessed based on the distribution of these contaminants. The main issues of this thesis were described as follows:(1)An analytical method was presented for the determination of 20 OCPs in soils by gas chromatography-electron capture detector (GC-ECD) with accelerated solvent extraction (ASE) and florisil solid phase extraction (SPE) purification. The factors such as instrument conditions of ASE, kinds and dosage of eluent for Florisil SPE purification and GC chromatographic separation conditions were optimized. The established method had the advantages of excellent separation efficiency and elimination of disturbance. The limits of detection (LODs) were 0.1-10.5 ng/g. The relative standard deviations (RSDs) of 20 OCPs were all below 20%. Except a higher recovery of Endrin and a lower recovery of Endrin aldehyde, the recoveries of the rest 18 OCPs ranged from 64.5% to 123.4%.(2)An analytical method was presented for the determination of 16 PAHs in soils by high effective liquid chromatography (HPLC) with ASE and Silica SPE cleanup. The established method had the advantages of excellent separation efficiency and elimination of disturbance, with the detection limits as 0.1-2 ng/g. The RSDs for the methods were 1.9%-9.5%, and the recoveries of 16 PAHs ranged from 61.2% to 118.5%. The quantum method was sensitive and accurate, and met determination requirements of trace PAHs in soil samples.(3)Methods for the rapid determination of 8 PFCs in sediment and fish samples were developed by isotope dilution ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sediment and fish samples were extracted respectively with methanol and acetonitrile after addition of eight isotopically labeled internal standards using an ultrasonic bath. The extract was cleaned up by WAX solid phase extraction column. The target compounds were separated on ZORBAX Eclipse plus C18 and analyzed by a triple quadruple tandem mass spectrometer with electrospray ionization source (ESI) in multiple reaction monitoring (MRM) mode. The samples were quantified by the internal standards labeled with stable isotopes. The standard curves were linear in the ranges of 0.1-20.0μg/L for 8 PFCs with correlation coefficients greater than 0.98. The LODs and limit of quantification (LOQs) were 0.001-0.004 ng/g dry weight (dw) and 0.003-0.013 ng/g dw for sediment systems. The average recoveries and the RSDs of PFCs in sediments were in the range of 67%-104% and 1.1%-8.8%, respectively. The LODs and LOQs for PFCs in fish samples were 0.03-0.15 ng/g dw and 0.10-0.45 ng/g dw, respectively. The average recoveries and the RSDs of PFCs in fish samples were in the range of 87.7%-104.4% and 4.1%-10.7%, respectively. The results showed that the methods were sensitive and accurate, and suitable for the qualitative and quantitative determination of PFCs residues in sediment and fish samples. (4)Samples of vegetable soils were collected from three cities (Wuhan, Yichang and Xiangyang) of Hubei. The characteristics, sources, ecological and health risks of OCPs in the soils were investigated and assessed. Results showed that OCPs were detectable in all soil samples, and the residues of OCPs ranged from 21.0 to 592 ng/g. The concentrations of HCHs and DDTs in most soil samples were lower than the two corresponding level standard values of "China’s soil environmental quality standard". Based on the factor analysis, p,p’-DDT and p,p’-DDE were the major pollutants, and which may have potential ecological impact on the study area. By the characteristic ratio method, it is speculated that DDTs residues mainly both came from either early or recently input of traditional industrial DDTs or dicofol, HCHs originated mainly from lindane, and chlordane mainly came from early input. The ecological risk level of HCHs was low, while the residues of DDTs would pose adverse biological effects on the study area. The non-carcinogenic and carcinogenic risks of OCPs were very low in all soil samples.(5)The results showed that the total concentrations of 16 PAHs (∑PAHs) ranged from 4.33 to 876.8 ng/g in agricultural and vegetable soils from typical regions (Wuhan, Yichang, Xiangyang, Jingzhou) of Hubei, with a mean of 72.4 ng/g. The compositions of PAHs in these soils except that of Jingzhou were characterized by the medium-high molecular weight PAHs. The factor analysis and PAHs isomeric ratios indicated that PAHs in soils from all regions originated mainly from combustion. PAHs in some vegetable soils (Yichang, Jingzhou and Xiangyang) had some relationship to traffic pollution. The ecological risk level of PAHs was low. The health risk assessment suggested that the non-carcinogenic and carcinogenic risks of PAHs in soils from the study regions were lower than other areas.(6)Eight perfluorinated compounds (PFCs) were determined based on the upper surface sediments collected from Danjiangkou Reservoir in China. The total PFC concentration ranged between 0.272 and 0.394 ng/g dw in all sampling sites. The concentrations of perfluorooctane sulfonate (PFOS) and perfluoro-n-butanoic acid (PFBA) were higher than those of other PFCs, which ranged between 0.057-0.090 ng/g dw and 0.053-0.083 ng/g dw in surface sediments, respectively. Meanwhile, the concentration of perfluoro-n-octanoic acid was always below the LOD of 0.050 ng/g dw. The order of PFC concentrations in the sediments from Danjiangkou Reservoir was as follows:upstream area<downstream area. The relative abundance of PFOS in the surface sediments was slightly higher than that of PFBA, which accounted for 22.4%±2.2% of the total PFC concentration. The PFC concentrations in the surface sediments from Danjiangkou Reservoir were relatively low compared with the sediment PFCs determined in other regions. The risk quotient method was used for the ecological risk assessment of PFCs in sediment based on the measured concentration of PFCs in environment and the predicted no-effect concentration. The assessment results suggested that PFCs in sediments from Danjiangkou Reservoir had no ecological risk to environment.(7)Residues of eight PFCs were investigated in fifteen fish samples from the Danjiangkou Reservoir and Hanjiang River (Xiangyang and Zhongxiang sections). The total concentrations of PFCs in fish muscles ranged from 2.01 to 43.8 ng/g dw. The mean concentration of total PFCs from related muscles showed the following trend in various regions:Zhongxiang section< Xiangyang section< Danjiangkou Reservoir. PFOS was the dominant PFC in the fish liver samples from the Danjiangkou Reservoir. The calculated hazard ratio (HR) of PFCs for all fish muscle samples was less than 1.0, and could be classified at safe levels for the general population. However, yellow croaker fish from the Danjiangkou Reservoir and Hanjiang River-Xiangyang section had HRs of 0.2, indicating that frequent consumption of this contaminated fish may pose an unacceptable risk to human health.