Use of Membranes and Detailed HYSPLIT Analyses to Understand Atmospheric Particulate, Gaseous Oxidized, and Reactive Mercury Chemistry
Use of Membranes and Detailed HYSPLIT Analyses to Understand Atmospheric Particulate, Gaseous Oxidized, and Reactive Mercury Chemistry
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DOI：
10.1021/acs.est.0c07876
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发表时间：
2021-01-06
影响因子：
11.4
通讯作者：
Castro, Mark
中科院分区：
文献类型：
--
作者：
Gustin, Mae Sexauer;Dunham-Cheatham, Sarrah M.;Castro, Mark
大气是汞进入生态系统的主要途径。尽管大气沉积的重要性，但气态氧化态（GOM）和颗粒结合态（PBM）汞的浓度和化学性质的特征很差。在此，使用三种膜（阳离子交换（CEM）、尼龙和聚（PTFE）膜）作为GOM和PBM的浓度定量和化学鉴别的手段。详细的HYSPLIT分析用于确定形成活性汞的氧化剂的来源（RM = PBM + GOM）。尽管采样分辨率较低（1-2周），但观察到了化学梯度，太平洋上空以卤化化合物为主，内华达州和犹他州的海洋边界层继续影响，马里兰州定期出现。氧化物基RM化合物通过远距离迁移到达大陆。氮，硫和有机RM化合物与区域和当地的空气质量。RM浓度在海洋上最高，在美国从西向东逐渐降低。膜浓度的比较表明，CEM提供了RM浓度的定量测量，PTFE膜可用于收集PBM。尼龙膜在环境空气中不能以相同的效率保留所有化合物，因此需要替代的解吸表面。
The atmosphere is the primary pathway by which mercury enters ecosystems. Despite the importance of atmospheric deposition, concentrations and chemistry of gaseous oxidized (GOM) and particulate-bound (PBM) mercury are poorly characterized. Here, three membranes (cation exchange (CEM), nylon, and poly(tetrafluoroethylene) (PTFE) membranes) were used as a means for quantification of concentrations and identification of the chemistry of GOM and PBM. Detailed HYSPLIT analyses were used to determine sources of oxidants forming reactive mercury (RM = PBM + GOM). Despite the coarse sampling resolution (1-2 weeks), a gradient in chemistry was observed, with halogenated compounds dominating over the Pacific Ocean, and continued influence from the marine boundary layer in Nevada and Utah with a periodic occurrence in Maryland. Oxide-based RM compounds arrived at continental locations via long-range transport. Nitrogen, sulfur, and organic RM compounds correlated with regional and local air masses. RM concentrations were highest over the ocean and decreased moving from west to east across the United States. Comparison of membrane concentrations demonstrated that the CEM provided a quantitative measure of RM concentrations and PTFE membranes were useful for collecting PBM. Nylon membranes do not retain all compounds with equal efficiency in ambient air, and an alternate desorption surface is needed.