Seasonal Variation And Potential Sources Of PCBs In The Atmosphere In Dalian Areas

Polychlorinated biphenyls (PCBs) are one of the 12 persistent organic pollutants (POPs) targeted by the Stockholm Convention on POPs. PCBs are stable in the environment, undergo long-range atmospheric transport (LRAT) and possess the ability to bioaccumulate through the food chain with the potential of toxic effects to humans and biota. A seasonal field campaign by passive sampling was conducted from February 2008 to February 2009, aiming to measure air concentrations of Polychlorinated Biphenyls (PCBs) in the urban and suburban areas in Dalian. The measured air concentrations of PCB52,44,101,118,153,138,180,206 at the urban site during the campaign were 36.09-314.75,27.30-157.96,4.17-58.87,15.45-93.21,2.50-42.28,1.00-63.00,56.37-212.36,0.48-30.35 pg/m3 respectively, and the suburban site the measured air concentrations of PCB52,44,101,118,153,138,180,206 were 7.34-69.18,4.67-843.73,0.22-29.11,0.84-20.85,1.29-22.86,0.59-33.18,13.84-84.14,0.32-14.05 pg/m3 respectively. The air concentrations of PCB52,44,101,118,153,138,180,206 accounted for of the total air concentrations of PCBs at the urban site 46%,2%,13%, 1%,10%,1%,27%,1%. At the suburban site, the ratio was 9%,55%,4%,4%,4%,5%, 19%,1% respectively.Back trajectory analysis revealed that the air concentration of PCBs increased with the input of air masses from the land whereas decreasing air concentration of PCBs at the urban site was associated with air masses from the sea. Though long-range atmospheric transport from other sources might also contribute to atmospheric levels of this chemical over this coastal city. PCBs in the air in Dalian might result from the atmospheric transport of the air masses from northeast area, Shandong peninsula and Korean peninsula.The PCB homologue composition in air was similar to the technical PCBs in China, which were mainly low chlorinated benzene of tetrachlorobiphenyl,pentachlorobiphenyl, there were no significant difference between the composition of PCBs in air in unban and suburban(P>0.05). The concentrations of PCBs in air had a strong difference between unban and suburban, in spring and winter, the concentration in unban site was 2-3 times higher than that in suburban site, the city might be the mainly source, the PCBs in air was mainly from the second-emission of surface residue, this was coursed by the widely use of PCBs in history in this region, which degraded to the surface.