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A case study of Asian dust storm particles: Chemical composition, reactivity to SO₂ and hygroscopic properties

Ma, Qingxin, Liu, Yongchun, Liu, Chang, Ma, Jinzhu, He, Hong
Journal of environmental sciences (China) 2012 v.24 no.1 pp. 62-71
Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, aerosols, air, calcium carbonate, case studies, chemical composition, climate, dust storms, hygroscopicity, nitrates, organic compounds, prediction, silica, sulfur dioxide, uncertainty, China
Mineral dust comprises a great fraction of the global aerosol loading, but remains the largest uncertainty in predictions of the future climate due to its complexity in composition and physico-chemical properties. In this work, a case study characterizing Asian dust storm particles was conducted by multiple analysis methods, including SEM-EDS, XPS, FT-IR, BET, TPD/mass and Knudsen cell/mass. The morphology, elemental fraction, source distribution, true uptake coefficient for SO₂, and hygroscopic behavior were studied. The major components of Asian dust storm particles are aluminosilicate, SiO₂ and CaCO₃, with organic compounds and inorganic nitrate coated on the surface. It has a low reactivity towards SO₂ with a true uptake coefficient, 5.767×10⁻⁶, which limits the conversion of SO₂ to sulfate during dust storm periods. The low reactivity also means that the heterogeneous reactions of SO₂ in both dry and humid air conditions have little effect on the hygroscopic behavior of the dust particles.