| The Yangtze River Delta region is China’s eastern coastal Yangtze River into the sea, and it is the largest economic zone in China. However, over the years, the discharge of waste water has been high, making its pollution is becoming increasingly serious, while there are a number of drinking water sources along it. The safety of drinking water has been a people’s livelihood projects, in recent years, with the development of China’s economy and the improvement of living standards, the pollution levels of trace contaminants in drinking water has become the concern of the public. This study collected the different types of water and sediment in the Yangtze River Delta region to study the pollution levels and risks of Volatile organic compounds (VOCs), organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in water and sediment.Firstly, the laboratory analysis methods of VOCs, OCPs and PAHs in water and sediment were established. (1) Method for measurement of purgeable organic compounds in water by capillary column gas chromatography/mass spectrometry (GC-MS):The detection limit ranged from 0.13 to 409 ng·L-1, and the recovery ranged from were from 96.9% to 106% (RSD%=3.8%, n=5), from 97.8% to 107% (RSD%=3.6%, n=5), from 97.7% to 100% (RSD% 1.0%, n=5), with spiked 0.6μg·L-1,6μg·L-1 and 30μg·L-1 of VOCs in water, respectively. (2) Method for pesticides in water and sediment by isotope dilution high resolution gas chromatography high resolution mass spectrometry (HRGC-HRMS):The detection limits of OCPs in the water and sediment ranged from 0.06 to 1.9 pg·L-1, from 0.03 to 0.95pg·g-1, respectively. The recovery ranged from 87 to 99% (RSD%=5.3%, n= 4) in water with spiked 1 ng·L-1 of OCPs, and ranged from 64 to 97% (RSD%=13.6%, n= 4) in sediments with spiked 0.5 ng·g-1 of OCPs. (3) Method for PAHs in water and sediment by isotope dilution high resolution gas chromatography high resolution mass spectrometry (HRGC-HRMS), The detection limit ranged from 1.4 to 3.2 pg·L-1 in water, and from 0.7 to 1.6 pg·g-1 in sediment, respectively. The recovery ranged from 89 to 97% (RSD%=3.6%, n=4) in water with spiked 1 ng·L-1 of PAHs, and ranged from 69 to 98% (RSD%=12.1%, n= 4) in sediments with spiked 0.5 ng·g-1 of PAHs, respectively.On the basis of the method established, in April 2015, we collected the water and sediment of the Yangtze River, Taihu, Qian Tang River, Jiaxing, Huangpu River, to determine VOCs, OCPs, PAHs in water and sediment, respectively. For VOCs, the results show that the concentration of VOCs ranged from 503 to 42317 ng·L-1; the predominant contaminants was dichloromethane, chloroform, benzene,1,2-ichloro ethane, toluene, m-xylene and p-xylene, o-xylene, the detection rate was 100%. The concentrations of VOCs descended in the order: Taihu Lake> Qiantang River, Jiaxing> the Yangtze River. The level of VOCs in water from drinking water sources of Taihu Lake is much higher than that in drinking water sources of rivers. The concentration of VOCs in water from different drinking water sources were lower than that the limits specified in the "standards for drinking water quality" (GB5749-2006), According to the health risk assessment model, the non carcinogenic risk of VOCs in drinking water source is lower than the acceptable level of 1, and the risk of cancer is far lower than the acceptable level of 10"6, The concentration of VOCs in drinking water sources of the Yangtze River Delta region has no carcinogenic risk to human health.For OCPs, the total concentration of OCPs ranged from 1.48 to 341 ng·L-1 in water, and ranged from 0.46 to 93 ng·g-1 dry weight in sediments. The levels of OCPs in water were consisted with those in sediments. In sediments, all of the 22 organochlorine pesticides were detected, and DDTs, hexachlorobenzene, BHCs and pentachlorobenzene were detected in all samples. The concentrations of OCPs descended in the order:Jiaxing river network (ranged from 1.71 to 61 ng·g-1, median:12.4 ng·g-1)> the Yangtze River (ranged from 0.46 to 93 ng·g-1, median:8.59 ng·g-1), Qiantang River (ranged from 1.02 to 69 ng·g-1, median:8.1 ng·g-1) > Taihu (ranged from 1.76 to 8.65 ng·g-1, median:3.53 ng·g-1). The concentration of DDT and its degradation products were comparable with other areas. The sources of OCPs were drawn by principal component analysis and compositional pattern of DDTs, BHCs and chlordane. The dominant OCPs were chlordane, nonachlor and BHCs in sediments from drinking water sources of Jiaxing river network, it suggesting that illegal use of chlordane, and BHCs residue in this region. In drinking water sources of Qiantang River, the dominant OCPs were chlordane, nonachlor and BHCs, there was y-BHC input freshly in this region. The dominant OCPs were DDTs and BHCs in sediments from drinking water sources of Taihu, and there were DDTs and BHCs input freshly. In drinking water sources of the Yangtze River, the dominant OCPs were o, p’-DDT and HCHs, this may be indicative of a new input from the DDT impurity in dicofo and residue of BHCs. The environmental risk assessment results indicated DDTs in sediments pose a potential ecological risk to consumers of bottom feeders, which 74% and 2% sediment samples pose potential ecological risk and ecological risk, respectively.As for PAHs, the concentration of 16 PAHs ranged from 4.26 to 406 ng·L-1 in water, and ranged from 139 to 7955 ng·g-1 dw in sediments. The concentrations of PAHs in water were not consistent with those in sediment. All of the 16 kinds of PAHs were detected in sediments, The concentrations of PAHs descended in the order:Jiaxing (ranged from 139 to 3109 ng·g-1, median:1281 ng·g-1)> Yangtze River (ranged from189 to 7955 ng·g-1, median:747 ng·g-1)> Taihu(ranged from597 to 2467 ng·g-1, median:807 ng·g-1)> Qiantang River(ranged from186 to 2230 ng·g-1, median:500 ng·g-1). Pyrene is the predominant contaminants in sediments from Taihu Lake, while phenanthrene and fluoranthene were dominant in sediments from Yangtze River, Qiantang River and Jiaxing. The sources of PAHs identified showed that PAHs mainly come from the burning of coal in Jiaxing, Taihu, the Yangtze River, the Huangpu River, and mainly from firewood burning in Qian Tang river. The pollution level of PAHs in the Yangtze River Delta region is in medium level compared with other areas. The environmental risk assessment results indicated fluorene in sediments pose a potential ecological risk to consumers of bottom feeders, which 89% sediment samples pose potential ecological risk and ecological risk. |
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