Simultaneous monitoring of PCB profiles in the urban air of Dalian, China with active and passive samplings

The concentration of polychlorinated biphenyls （PCBs） in the urban air of Dalian, China was monitored from November 2009 to October 2010 with active high-volume sampler and semipermeable membrane device （SPMD） passive sampler. The concentration of PCBs （particle ＋ gas） （∑PCBs） ranged from 18.6 to 91.0 pg/m3, with an average of 50.9 pg/m3, and the most abundant dioxin-like PCB （DL-PCBs） was PCB118. The WHO-TEQ values of DL-PCBs were 3.6--22.1 fg/m3, with an average of 8.5 fg/m3, and PCB126 was the maximum contributor to ZTEQ. There was a much larger amount of PCBs in the gas phase than in the particulate phase. The dominant PCB components were lower and middle molecular weight PCBs. With increasing chlorination level, the concentration of the PCB congeners in the air decreased. The gas-particulate partitioning of PCBs was different for the four seasons. The gas- particulate partitioning coefficients （logKp） vs. subcooled liquid vapor pressures （logPL~） of PCBs had reasonable correlations for different sampling sites and seasons. The absorption mechanism contributed more to the gas-particulate partitioning process than adsorption. Correlation analysis of meteorological parameters with the concentration of PCBs was conducted using SPSS packages. The ambient temperature and atmospheric pressure were important factors influencing the concentration of PCBs in the air. The distribution pattern of the congeners of PCBs and the dominant contributors to DL-PCBs and TEQ in active samples and SPMDs passive samples were similar. SPMD mainly sequestrated gas phase PCBs.