Direct observation of completely processed calcium carbonate dust particles
Direct observation of completely processed calcium carbonate dust particles
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DOI：
10.1039/b417366j
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发表时间：
2005-01-01
影响因子：
3.4
通讯作者：
Rudich, Y
中科院分区：
文献类型：
--
作者：
Laskin, A;Iedema, MJ;Rudich, Y
本研究提出，第一次，现场证据的完整的，不可逆的处理固体碳酸钙（方解石）含颗粒和定量形成的液体硝酸钙颗粒显然是由于含碳酸钙的矿物粉尘颗粒与气态硝酸的非均相反应。在以色列Shoresh收集的气溶胶样品中，个别方解石和海盐颗粒的硝酸盐形成随时间的变化。使用传统的扫描电子显微镜与X射线能量色散分析（SEM/EDX）和计算机控制的SEM/EDX观察单个颗粒的形态和组成变化。利用环境扫描电子显微镜（ESEM）来确定和证明在一些样品中发现的硝酸钙颗粒的吸湿行为。硝酸钙颗粒即使在低于典型大气环境的9- 11%的非常低的相对湿度（RH）下也是异常吸湿和潮解的。非吸湿的干矿物粉尘颗粒转化为吸湿的湿气溶胶可能对光散射特性、改变云的能力和非均质化学产生重大影响。
This study presents, for the first time, field evidence of complete, irreversible processing of solid calcium carbonate (calcite)-containing particles and quantitative formation of liquid calcium nitrate particles apparently as a result of heterogeneous reaction of calcium carbonate-containing mineral dust particles with gaseous nitric acid. Formation of nitrates from individual calcite and sea salt particles was followed as a function of time in aerosol samples collected at Shoresh, Israel. Morphology and compositional changes of individual particles were observed using conventional scanning electron microscopy with energy dispersive analysis of X-rays (SEM/EDX) and computer controlled SEM/EDX. Environmental scanning electron microscopy (ESEM) was utilized to determine and demonstrate the hygroscopic behavior of calcium nitrate particles found in some of the samples. Calcium nitrate particles are exceptionally hygroscopic and deliquesce even at very low relative humidity (RH) of 9-11 % which is lower than typical atmospheric environments. Transformation of non-hygroscopic dry mineral dust particles into hygroscopic wet aerosol may have substantial impacts on light scattering properties, the ability to modify clouds and heterogeneous chemistry.