Characterization of individual submicrometer aerosol particles collected in Incheon, Korea, by quantitative transmission electron microscopy energy‐dispersive X‐ray spectrometry

Abstract

[1] For the last decade the Monte Carlo calculation method has been proven to be an excellent tool for accurately simulating electron-solid interactions in atmospheric individual particles of micrometer size. Although it was designed for application to scanning electron microscopy, in the present study it is demonstrated that the Monte Carlo calculation can also be applied in a quantitative single particle analysis using transmission electron microscopy (TEM) with an ultrathin window energy-dispersive X-ray (EDX) spectrometer with a high accelerating voltage (200 kV). By utilizing an iterative reverse Monte Carlo simulation combined with successive approximation, atomic elemental concentrations (including low-Z elements) of submicrometer standard particles were determined with high accuracy for electron beam refractory particles such as NaCl, KCl, SiO 2 , Fe 2 O 3 , Na 2 SO 4 , K 2 SO 4 , CaCO 3 , and CaSO 4 . On the basis of quantitative X-ray analysis together with morphological information from TEM images, overall 1638 submicrometer individual particles from 10 sets of aerosol samples collected in Incheon, Korea, were identified. The most frequently encountered particle types are carbonaceous and (NH 4 ) 2 SO 4 /NH 4 HSO 4 -containing particles, followed by mineral (e.g., aluminosilicate, SiO 2 , CaCO 3 ), sea salt, K-rich (e.g., K 2 SO 4 and KCl), Fe-rich, fly ash, and transition or heavy-metal-containing (e.g., ZnSO 4 , ZnCl 2 , PbSO 4 ) particles. The relative abundances of the submicrometer particle types vary among samples collected in different seasons and also depend on different air mass transport routes. This study demonstrates that the quantitative TEM-EDX individual particle analysis is a useful and reliable technique in characterizing urban submicrometer aerosol particles.

Mixed Chloride Aerosols and their Atmospheric Implications: A Review

“…A fraction of the particulate chlorides in sea salts is converted into gas-phase compounds (e.g., HCl and ClNO 2 ), with most of the remaining chlorides completely encased within a large quantity of inorganic elements (as shown in Fig. 2(b)) (e.g., Mg and S at Cape Grim , K, Ca, and S in Incheon (Geng et al, 2010), Mg, K, Ca, and S in Antarctica (Hara et al, 2005), and Mg, N, and S in Houston, Macao, and Hong Kong (Laskin et al, 2002;Li et al, 2010Li et al, , 2016a). Amorphous sodium chloride particles were found to be completely bound with sodium nitrates and sodium sulfates in coastal Hong Kong (Li et al, 2016a).…”

“…Electron microscopy and single-particle mass spectrometry have indicated that potassium chlorides in biomass burning smoke mix with soot and organics, and some even acquire an organic surface coating (Silva et al, 1999;Li et al, 2003b). In urban areas, field studies have detected plentiful submicron metal chloride containing particles, which are typically mixed with carbonaceous materials in combustion emissions (Moffet et al, 2008b;Li et al, 2009;Geng et al, 2010;Hu et al, 2015). Additionally, in long-range transport dust plumes over the Pacific, Sullivan et al (2007b) observed that a large amount of secondary particulate chlorides (produced from gas-phase HCl) was internally mixed with dust particles.…”

Ultrafine Particle Events in the Ambient Atmosphere in Korea

“…Morphology and EDS data suggest that the particles were regarded as mixtures of semi and/or less volatile organic species and ammonium sulfate/bisulfate (see Fig. 9c) (Geng et al, 2010). Approximately 12 over 95 particles were identified to be of this type in the photochemical event in urban Gwangju together with industrial Yeosu sites.…”

“…UFP number concentrations, gaseous pollutants, and meteorological data, averaged by the time of day, obtained in urban Gwangju , 2010, 2011, and 2012), coastal Taean (2008), and industrial Yeosu (2008 sites in Korea by continuously measuring particle number size distribution N (13-615 nm) are summarized in Table 1. The variation of UFP number concentrations in three different sampling sites: Gwangju, Taean, and Yeosu, and seasonal and long-term variations in urban Gwangju are described as follows.…”

“…The average UFP number concentrations measured at three sampling sites were compared to the maximum UFP number concentrations in the UFP events, where a significant increase of the concentrations was observed in all the events. The average and maximum concentration of UFP number concentrations in the UFP events were 4.80×10 3 cm A total of 128 days samples were measured during different seasons in urban Gwangju (2007, 2010, 2011, and 2012), industrial Yeosu (2008, and coastal Taean (2008) sites. In this work, UFP events were identified and classified into different types by applying the approach as described above and analyzed the samples.…”