| PCBs (Polychlorinated biphenyls) and PBDEs (Polybrominated diphenyl ethers), are a class of POPs which have been detected in various environmental media (air, sediment, soil, water) and biological samples. At present, there is no report about DL-PCBs and PBDEs exchange in air-water-sediment in Taihu Lake environmental media. Therefore, the DL-PCBs and PBDEs level in surface sediments core, atmosphere, water from Taihu Lake were studied to discuss the distribution trend of DL-PCBs and PBDEs in Taihu Lake, combined with the level of DL-PCBs and PBDEs in atmosphere and water, a preliminary investigation of the exchange flux of DL-PCBs and PBDEs in Taihu Lake region will be carried out.Gas chromatography-negative chemical ionization-mass spectro-metry method was to determinate DL-PCBs. It revealed that the distribution trends of∑DL-PCBs and∑8PBDEs in surface sediments from Taihu Lake in the north shore were higher than the south. The level of the∑DL-PCBs ranged from7.1to354.6pg·g-1dw (dry weight), the mean level was91pg·g-1dw, PCB-118was the most abundant congener, followed by PCB-77and PCB-105. The level of∑8PBDEs were ranged from0.56to213.2ng·g-1dw, the mean level was20.2ng·g-1, BDE-209level were ranged from0.20to212.9ng·g-1dw, which meadia and mean values were9.9ng·g-1dw, the19.9ng·g-1dw, respectively. BDE-209in the sediment were ranged from76.2%to99.9%in the∑8PBDEs, it was the main PBDEs congener.The level of∑8DL-PCBs in core sediment of Taihu Lake ranged from33.9to99.3pg·g-1dw, with a mean level43.44pg·g-1dw, PCB-77,-105and-118were main DL-PCBs congeners. The level of∑8PBDEs ranged from2.02to167.60ng·g-1dw, with a mean level23.14ng·g-1dw. The level of BDE-209contributed to47.6-99.8%(mean:89.3%) to∑8PBDEs, which was the main PBDEs homologues. The highest PBDEs levels were found in Zhushan Bay, followed by Mei Liang Bay and South Taihu Lake. The level of DL-PCBs in Meiliang Bay were the highest, followed by Zhu Shan Bay and South Taihu Lake. In the upper sediment (0-15cm), the level of PCB-77,-118and-105decrease obviously with increasing depth, but it did not change significantly in the lower sediments (15-30cm). PBDEs level increased exponentially in the upper sediment (0-15cm) of the three sampling sites, BDE-209was the major PBDEs congener, but there were some differences of PBDEs patterns distribution in the vertical sediments, this may imply the degradation of BDE-209in sediment burial.Based on the establishment of air-water exchange and water sediment exchange model, the exchange trends and exchange fluxes of DL-PCBs and PBDEs in Taihu Lake region have been estimated. The exchange trends of DL-PCBs were mainly generally volatilization, and ∑DL-PCBs’volatilization flux was3183.2pg·m-2·day-1, the major exchange congeners were PCB-77,-105,-118and-123. The trends of sediment-water exchange of DL-PCBs were deposited from the sediment to the water. The deposition flux of∑DL-PCBs was5225.7pg·m-2·day-1, and the major exchange congeners were PCB-77,-105and-118.The air-water exchange of BDE-28,-47,-100,-153and-209were evaporated from the water to the atmosphere, with a flux of16.59-121.82ng·m-2day-1while the transport trend of BDE-99,-154,-183were from the atmosphere into the water and with a deposition flux of3.26-4.46ng·m-2·day-1,∑8PBDEs volatilization flux was253.5ng·m-2·day-1. The total exchange flux were mainly impacted by BDE-209. The sediment-water exchange flux of PBDEs were deposited from the sediment into the water with a flux of501.7ng·m-2day-1, BDE-209was the main contributor. |
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