中文摘要：

为了解西安城区大气中多氯联苯（PCBs）的气粒分配规律,于2012年春季对西安城区大气中气态和颗粒态样品进行每周一次的主动采样.结果表明,西安城区大气中PCBs的总浓度（气态和颗粒态）为62.05~454.18pg/m3,主要以气态为主.由Clausius-Clapeyron方程得到的斜率较陡（-5193.24）,表明春季大气中的PCBs主要受西安城区附近地面挥发释放的影响.PCBs的气粒分配系数（KP）与过冷饱和蒸汽压（PoL）高度相关,由logKP和logPoL线性回归得到的斜率mr（-0.46~-0.37）均高于平衡状态理论值-1,说明西安城区大气中的PCBs气粒分配尚未达到平衡状态.采用Junge-Pankow吸附模型和Harner-Bidleman吸收模型对PCBs颗粒态百分比（φ）及KP进行了模拟,结果显示两种模型均较好地预测了PCBs的气粒分配行为,但与实验测得的值相比,两种模型均高估了φ值及KP值.

英文摘要：

In order to study the gas-particle partitioning of polychlorinated biphenyls （PCBs） in ambient air of Xi’an City, China, both gas and particle phases samples were collected using an active air sampler on a weekly base during spring in 2012. The results showed that the total concentration （gas plus particle phases） of PCBs ranged from 62.05 to 454.18 pg/m3, with much higher concentration in gas phase than that in particle phase. The steep slope （-5193.24） obtained from Clausius-Clapeyron equation indicated that PCBs concentration in Xi’an City was mainly influenced by the evaporation from adjacent land surface. Gas-particle partitioning coefficients （KP） of PCBs were well correlated with the sub-cooled vapor pressure （PoL） however, the slopes （-0.46~-0.37） obtained from linear regression between logKP and logPoL were shallower than the theoretical value of-1 at equilibrium condition. The results indicated that partitioning of PCBs between the gas and particle phases in the air in Xi’an City was under non-equilibrium condition. The particle bound fraction （φ） and KP value were estimated using the Junge-Pankow adsorption model and Harner-Bidleman absorption model, the result showed that gas-particle partitioning of PCBs was well simulated by both models, however, both models tended to overestimate the values ofφand KP compared with those obtained from field measurement.