| Polychlorinated biphenyls (PCBs) are a class of synthetic organic chloride, which have been widely used in many fields (electric power, plastics processing, chemical engineering, print et al.) as heat exchange liquids, plasticizer, pesticide extenders and carbonless copy paper. Effects attributed to PCBs include changes in the immune system, behavioral alterations, impaired reproduction, teratogenic and carcinogenic effect, PCBs have attracted a great deal of scientific and public attention due to their adverse health effects on the development and reproduction of fish, wildlife and even humans. Distribution characteristics of PCBs in water from China are investigated that is increased continuously. However, the distribution characteristics of PCBs in water from Dianchi Lake have been poorly investigated. In this study we assess the level and distribution characteristics of PCBs in Dianchi Lake, to provide basis for PCBs control.Six indicator PCB congeners (PCB28, PCB52, PCB101, PCB138, PCB153 and PCB180) are assessed contamination levels of PCBs in Global Environment Monitoring System/Food Contamination Monitoring and Assessment Programme (GEMS/Food).The selected targets compounds are six indicator PCB congeners, which range from Trichlorobiphenyl to Heptachlorobiphenyl.The presences of PCBs in selected 10 monitoring points of Dianchi Lake are described, and assess the level and distribution characteristics of PCBs in Dianchi Lake.The optimization conditions of analytical method, GC-MS analysis are studied:Samples are separated on a 30m×0.25um×0.25um of DB-5/MS in GC-MS, the initial temperature is 100℃for 1 min and increased to 260℃/min at 18℃/min, then it is increased to 280℃/min at 20℃/min, and hold for 3min. Solid-phase extraction are also studied, including SPE cartridge, pH, condition of HLB-SPE, extract solvent and flow rate, The main optimized experimental conditions are presented as follows:for an HLB-SPE, pH=7, condition:3x5mL DCM, MeOH, water, the cartridge is sequentially washed with methanol/water (2.5:97.5, v/v) and eluted with 22mL of hexane/DCM (50:50, v/v) mixture. The-water sample and eluent are flowed through at a flow rate of 8.0 to 10ml/min, and 3.0ml/min, respectively. The recoveries were ranged from 77.9% to 85.1% with relative standard deviations (RSD) 3.1-7.8%(n=3).Under the conditions of optimized analytical method, the results confirm that the pollution of PCBs belong to the middle and upper level in Dianchi Lake. The PCBs concentrations in dry and wet season were ranged from 0.3-60.8ng/L and 3.8～35.7ng/L, respectively. Compared with the national surface water environment quality criterion (GB3838-2002) of 20ng/L, the concentration of PCBs in Dianchi Lake is more than the criterion. Therefore, it is urgent time to take actions to control PCBs pollution. |
