Uptake and Mobilization of Organic Chemicals with Clouds: Evidence from a Hail Sample

详细信息    查看全文

• 作者：Jianmin Ma ; Ed Sverko ; Yushan Su ; Junhua Zhang ; Hong Gao
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：September 3, 2013
• 年：2013
• 卷：47
• 期：17
• 页码：9715-9721
• 全文大小：342K
• 年卷期：v.47,no.17(September 3, 2013)
• ISSN：1520-5851

文摘

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in hail samples collected during a storm that occurred on a spring morning in Toronto, Canada. The presence of these organic chemicals in hail suggests that clouds likely provide an atmospheric transport pathway for these substances in the free atmosphere. Results reported here may carry significant implications for atmospheric transport, mass balance, tropospheric cold trapping, and environmental fate of organic chemicals. Backward trajectories along with measured and modeled cloud cover show that clouds causing the hail event were formed and advected from the midwestern and southeastern United States. After being emitted to the atmosphere, the organic chemicals were likely lifted by atmospheric ascending motions to a higher atmospheric elevation and partitioned onto clouds. These clouds then carry the organic chemicals to a downwind location where they are deposited to the ground surface via precipitation. We found that the organic chemicals with high solubility and vapor pressure tend to partition into clouds through sorption to cloudwater droplets and ice particles. It was found that approximately 7鈥?0% of pyrene could be sorbed into cloudwater droplets and ice particles in this hail event at the expense of reduced gas-phase concentrations.