Study on the PCDD/Fs in Jiaozhou Bay of Qingdao, China

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in surface sediment and mussel samples from Jiaozhou Bay were analyzed using HRGC-HRMS (High Resolution Gas Chromatograph-High Resolution Mass Spectrometer) technique. The total PCDD/Fs content was in the range of 100 ~ 910 pg/g dw, and that of total 2,3,7,8-substituted PCDD/Fs contents was 4.1 ~ 232.4 pg/g dw. The distribution of the total 2,3,7,8-substituted PCDD/Fs in the sediments formed an east-west pattern under the action of cycle-flow. The highest level occurred near the river mouth was an order of magnitude higher than at other stations which was believed to be pollutant source. Except for the area near the river mouth, the relative contributions of individual 2,3,7,8-substituted congeners at each station were similar, i.e., the lower chlorinated congeners dominated over the higher chlorinated PCDD/Fs., and the source was believed to be the atmospheric deposition from long-range transport. The source of PCDD/Fs was relatively constant as evidenced by the PCDDs/PCDFs ratios and the OCDD %Sigma. The total 2,3,7,8-PCDD/Fs contents in the mussel sample ranged from 5.1 to 2.9 pg/g dw (52.1 ~ 35.4 pg/g lipid). The main sources of TEQ (Toxicity Equivalency Quantity) were 2,3,4,7,8-PeCDF (35%), 2,3,7,8-TCDF (30%), and 2,3,7,8-TCDD (30%).