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Gas-particle partitioning of polychlorinated biphenyls in air of Xi’an City |
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Abstract 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 of φ and KP compared with those obtained from field measurement.
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Received: 25 December 2013
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