Prince Amy Preszler, Kleiber Paul D, Grassian Vicki H, Young Mark A
Departments of Chemistry, The University of Iowa, Iowa City, IA 52242, USA.
Phys Chem Chem Phys. 2008 Jan 7;10(1):142-52. doi: 10.1039/b712915g. Epub 2007 Nov 21.
The heterogeneous chemistry of gas-phase acetic acid with CaCO(3)(calcite) aerosol was studied under varying conditions of relative humidity (RH) in an environmental reaction chamber. Infrared spectroscopy showed the loss of gas-phase reactant and the appearance of a gaseous product species, CO(2). The acetic acid is observed to adsorb onto the calcite aerosol through both a fast and a slow uptake channel. While the fast channel is relatively independent of RH, the slow channel exhibits enhanced uptake and reaction as the RH is increased. In additional experiments, the calcite aerosol was exposed to both nitric and acetic acids in the presence of water vapor. The rapid conversion of the particulate carbonate to nitrate and subsequent deliquescence significantly enhances the uptake and reaction of acetic acid. These results suggest a possible mechanism for observed correlations between particulate nitrate and organic acids in the atmosphere. Calcium rich mineral dust may be an important sink for simple organic acids.
在环境反应室中，研究了气相乙酸与碳酸钙（方解石）气溶胶在不同相对湿度（RH）条件下的非均相化学反应。红外光谱显示气相反应物的损失和气态产物二氧化碳的出现。观察到乙酸通过快速和缓慢吸收通道吸附到方解石气溶胶上。快速通道相对独立于相对湿度，而缓慢通道随着相对湿度的增加表现出增强的吸收和反应。在额外的实验中，方解石气溶胶在有水蒸气存在的情况下同时暴露于硝酸和乙酸中。颗粒状碳酸盐迅速转化为硝酸盐并随后潮解，显著增强了乙酸的吸收和反应。这些结果表明了一种可能的机制，用于解释大气中颗粒硝酸盐与有机酸之间观察到的相关性。富含钙的矿物尘埃可能是简单有机酸的重要汇。
