Asian dust particles converted into aqueous droplets under remote marine atmospheric conditions
Asian dust particles converted into aqueous droplets under remote marine atmospheric conditions
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DOI：
10.1073/pnas.1008235107
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发表时间：
2010-10
期刊：
影响因子：
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通讯作者：
Y. Tobo;Daizhou Zhang;A. Matsuki;Y. Iwasaka
中科院分区：
文献类型：
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作者：
Y. Tobo;Daizhou Zhang;A. Matsuki;Y. Iwasaka
尘埃颗粒在大气中的化学历史对于评估其对地球气候和生态系统的影响至关重要。到目前为止，许多研究表明，在强人为排放源附近，富钙尘埃颗粒主要通过与气态HNO 3反应生成Ca（NO3）2而转化为含水液滴。在这里，我们表明，其他类似的过程有可能在典型的远程海洋大气条件下被激活。根据在东亚几个地点的现场测量和热力学预测，我们研究了两种高溶解性钙盐，Ca（NO3）2和CaCl 2，这可以潮解在低相对湿度的形成的可能性。结果表明，在亚洲大陆的城市和工业化地区，不溶性CaCO_3向Ca（NO_3）_2的转化倾向于占主导地位，在这些地区，HNO_3的浓度超过HCl的浓度（[HNO_3/HCl] > 1）。在这种情况下，很难从尘埃颗粒中检测到CaCl 2。但是，在日本列岛附近，可以检测到CaCl 2的生成，因为HCl的浓度远高于HNO 3的浓度（[HNO 3/HCl] <0.3）。我们建议，在遥远的海洋边界层中的HCl浓度升高足以修改沙尘暴中的富钙颗粒，并可以发挥更重要的作用，在颗粒表面上形成潮解层，因为它们被运往遥远的海洋地区。
The chemical history of dust particles in the atmosphere is crucial for assessing their impact on both the Earth’s climate and ecosystem. So far, a number of studies have shown that, in the vicinity of strong anthropogenic emission sources, Ca-rich dust particles can be converted into aqueous droplets mainly by the reaction with gaseous HNO3 to form Ca(NO3)2. Here we show that other similar processes have the potential to be activated under typical remote marine atmospheric conditions. Based on field measurements at several sites in East Asia and thermodynamic predictions, we examined the possibility for the formation of two highly soluble calcium salts, Ca(NO3)2 and CaCl2, which can deliquesce at low relative humidity. According to the results, the conversion of insoluble CaCO3 to Ca(NO3)2 tends to be dominated over urban and industrialized areas of the Asian continent, where the concentrations of HNO3 exceed those of HCl ([HNO3/HCl] > ∼ 1). In this regime, CaCl2 is hardly detected from dust particles. However, the generation of CaCl2 becomes detectable around the Japan Islands, where the concentrations of HCl are much higher than those of HNO3 ([HNO3/HCl] < ∼ 0.3). We suggest that elevated concentrations of HCl in the remote marine boundary layer are sufficient to modify Ca-rich particles in dust storms and can play a more important role in forming a deliquescent layer on the particle surfaces as they are transported toward remote ocean regions.