Elevated Gaseous Oxidized Mercury Revealed by a Newly Developed Speciated Atmospheric Mercury Monitoring System.
Elevated Gaseous Oxidized Mercury Revealed by a Newly Developed Speciated Atmospheric Mercury Monitoring System.
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新开发的大气汞形态监测系统显示气态氧化汞含量升高。
DOI：
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发表时间：
2022
影响因子：
11.4
通讯作者：
Qingru Wu
中科院分区：
文献类型：
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作者：
Yi Tang;Shuxiao Wang;Guoliang Li;Deming Han;Kaiyun Liu;Zhijian Li;Qingru Wu
气态氧化汞（Hg 2+）监测是汞研究领域面临的最大挑战之一，现有方法无法同时满足准确度和时间精度的测量要求，特别是在高颗粒环境中。在这里，我们验证了双级阳离子交换膜（CEM）采样器是无法气态元素汞（Hg 0）的吸收，即使颗粒物被捕获的CEM，而汞2+捕获效率的采样器是超过90%。通过将双级CEM采样器与商用Tekran 2537/1130/1135系统耦合，并配置新的采样和分析程序，研制了阳离子交换膜耦合大气形态汞监测系统（CSAMS），以提高Hg 2+的监测精度，确保Hg 0、Hg 2+和Hgp在2 h时间分辨率下的同时测量。我们于二零二一年九月在北京市区部署CSAMS，并于日间观测到前所未有的Hg 2+升高，平均幅度为510 pg m-3。使用零维箱模型，升高的Hg 2+生产率归因于高大气氧化剂浓度，Hg 0的非均相和大气颗粒物表面的界面氧化过程，或潜在的未知氧化剂。
Gaseous oxidized mercury (Hg2+) monitoring is one of the largest challenges in the mercury research field, where existing methods cannot simultaneously satisfy the measurement requirements of both accuracy and time precision, especially in high-particulate environments. Here, we verified that dual-stage cation exchange membrane (CEM) sampler is incapable of gaseous elemental mercury (Hg0) uptake even if particulate matter is trapped on CEM, whereas the Hg2+ capture efficiency of the sampler is more than 90%. We then developed a Cation Exchange Membrane-Coupled Speciated Atmospheric Mercury Monitoring System (CSAMS) by coupling the dual-stage CEM sampler with the commercial Tekran 2537/1130/1135 system and configuring a new sampling and analysis procedure, so as to improve the monitoring accuracy of Hg2+ and ensure the simultaneous measurement of Hg0, Hg2+, and Hgp in 2 h time resolution. We deployed the CSAMS in urban Beijing in September 2021 and observed an unprecedented elevated Hg2+ during the daytime with an average amplitude of 510 pg m-3. Using a zero-dimensional box model, the elevated Hg2+ production rate was attributed to high atmospheric oxidant concentrations, Hg0 heterogeneous and interfacial oxidation processes on the surface of atmospheric particles, or potential unknown oxidants.