Abstract:In order to find out the concentration and pollution characteristics of polychlorinated biphenyls (PCBs) in topsoil and agricultural products in irrigation district at the southeastern suburb of Beijing, seven kinds of PCBs in 20 topsoil samples and 28 agricultural products samples in the irrigation district were detected by gas chromatographymass spectrometry (GC-MS) in 2015. Results showed that the total concentrations of PCBs in topsoil were ranged from ND (lower than the limits of detection) to 0.711776μg/kg, with average concentration of 0.43μg/kg. The concentration of PCBs was increased with the increase of sewage irrigation history. The concentrations of PCBs in topsoil were relatively lower as compared with those in soil reported in other places. According to soil quality guidelines in Canada and American researcher’s risk assessment report, the concentrations of PCBs in topsoil did not pose a threat to the surrounding ecological environment. The concentrations of PCBs in winter wheat, Chinese spring onion, eggplant, pear, sweet potato and Chinese kale were lower than the detection limit. The concentrations of PCBs in summer maize grain, Chinese flowering cabbage, oil seed raped were 0.17~0.47μg/kg, 1.63μg/kg and 5.91μg/kg, respectively. There was no significant difference for PCBs concentrations in summer maize grain among regions with different sewage irrigation histories. The concentrations of PCBs in agricultural products were relatively lower as compared with other studies. According to the tolerable daily intake (TDI) proposed by the U.S. Department of Health and Human Services, the concentrations of PCBs in agricultural products were less than the corresponding reference limit. For both soil and agricultural products, only the concentrations of 4-PCB were higher than the detection limit, so only 4-PCB could be detected, 1-PCB ~ 3-PCB and 5-PCB ~ 7-PCB could not be detected. The carcinogenic risk of adult and child caused by PCBs were 8.49×10-7 and 4.66×10-7, respectively. The noncarcinogenic hazard index of PCBs for child and adult were 3.88×10-1 and 1.41×10-1, respectively. All of them were lower than the threshold values proposed by US EPA. Dietary intake was the major route of human exposure, which accounted for 99.79%~99.95% of the total carcinogenic risk and 99.81%~99.94% of the total non-carcinogenic hazard index, respectively.
