Investigation of aged Asian dust particles by the combined use of quantitative ED-EPMA and ATR-FTIR imaging

Abstract

Abstract. In our previous works, it was demonstrated that the combined use of quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), which is also known as low-Z particle EPMA, and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) imaging has great potential for a detailed characterization of individual aerosol particles. In this study, extensively chemically modified (aged) individual Asian dust particles collected during an Asian dust storm event on 11 November 2002 in Korea were characterized by the combined use of low-Z particle EPMA and ATR-FTIR imaging. Overall, 109 individual particles were classified into four particle types based on their morphology, elemental concentrations, and molecular species and/or functional groups of individual particles available from the two analytical techniques: Ca-containing (38%), NaNO3-containing (30%), silicate (22%), and miscellaneous particles (10%). Among the 41 Ca-containing particles, 10, 8, and 14 particles contained nitrate, sulfate, and both, respectively, whereas only two particles contained unreacted CaCO3. Airborne amorphous calcium carbonate (ACC) particles were observed in this Asian dust sample for the first time, where their IR peaks for the insufficient symmetric environment of CO32− ions of ACC were clearly differentiated from those of crystalline CaCO3. This paper also reports the first inland field observation of CaCl2 particles probably converted from CaCO3 through the reaction with HCl(g). HCl(g) was likely released from the reaction of sea salt with NOx/HNO3, as all 33 particles of marine origin contained NaNO3 (no genuine sea salt particle was encountered). Some silicate particles with minor amounts of calcium were observed to be mixed with nitrate, sulfate, and water. Among 24 silicate particles, 10 particles are mixed with water, the presence of which could facilitate atmospheric heterogeneous reactions of silicate particles including swelling minerals, such as montmorillonite and vermiculite, and nonswelling ones, such as feldspar and quartz. This paper provides detailed information on the physicochemical characteristics of these aged individual Asia dust particles through the combined use of the two single-particle analytical techniques, and using this analytical methodology it is clearly shown that internal mixing states of the aged particles are highly complicated.

Isolation of a wide range of minerals from a thermally treated plant: Equisetum arvense, a Mare’s tale

“…The peak at ~1115 cm −1 (peak b) was attributed to sulphate groups as in CaSO 4 , corroborating the crystalline phase detected by XRD in Fig. 7a [60]. At higher temperatures (1100 °C), the peaks observed in the region of 800–1100 cm −1 were attributed to the silicate tetrahedral vibration commonly observed for wollastonite [57].…”

A review of single aerosol particle studies in the atmosphere of East Asia: morphology, mixing state, source, and heterogeneous reactions

“…Recently, Prather et al (2013) successfully revealed size resolved associations between inorganic and organic species within individual sea spray aerosols (i.e., chemical mixing state), covering two orders of magnitude in size from 30 nm to 3 mm, by integrating the results from several single particle techniques, including ATOFMS, STXM, and TEM. For the same particles on the substrate, the combined use of quantitative electron probe X-ray microanalysis (EPMA) with n aerosol mass spectrometer total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) imaging and Roman microspectrometry (RMS) were successfully applied to characterize the complex internal structure and physicochemical properties of the same ensemble of Asian dust particles (Sobanska et al, 2012;Song et al, 2013). NanoSIMS combined with TEM can determine even better the mixing state of organic aerosols in individual particles (e.g., Fig.…”

Evolution of aerosol chemistry in Xi'an, inland China, during the dust storm period of 2013 – Part 1: Sources, chemical forms and formation mechanisms of nitrate and sulfate

“…The Gobi desert of northern China and Mongolia and the Taklamakan desert of western China are the major source regions of East Asian dust (McNaughton et al, 2009;Mochida et al, 2007). Modeling results indicate that around 100−460 Tg yr −1 of dust is emitted annually from the East Asia source regions (Laurent et al, 2006) and transported eastwardly, exerting a significant impact on the atmosphere over the downwind regions, including eastern coastal China (Arimoto et al, 2006;Kim et al, 2004;Li et al, 2014;Li and Shao, 2009;Sun et al, 2010;, Korea (Geng et al, 2014;Song et al, 2013;Sullivian et al, 2007), Japan (Takahashi et al, 2011;Tobo et al, 2010;Uno et al, 2009) and western North America (Huebert et al, 2003;Leaitch et al, 2009;McNaughton et al, 2009;Parrington et al, 1983;Singh et al, 2009). A recent study found that dust from the Sahara and Asia is transported over the Pacific Ocean and increases the snow precipitation in mountainous areas of Nevada, USA (Creamean et al, 2013).…”

“…Due to the chemical affinity of nitrogen oxides and nitric acid with dust particles (Hanisch and Crowley, 2001;Mogili et al, 2006;Saliba and Chamseddine, 2012;Song et al, 2013;Usher et al, 2003), such a change in the atmospheric environment of China suggests that dust particle behavior might also be changing compared to the situations 10 years ago. Therefore, it is necessary to investigate the present physicochemical properties of airborne particles in the country during dusty periods.…”