Single-Particle Characterization of Four “Asian Dust” Samples Collected in Korea, Using Low-<i>Z</i> Particle Electron Probe X-ray Microanalysis

Ro, Chul-Un; Hwang, Heejin; Kim, Hyekyeong; Chun, Youngsin; Grieken, R. Van

doi:10.1021/es049772b

Cited by 99 publications

(96 citation statements)

References 35 publications

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“…As presented in Table 2, the ratios range from 0.39 to 0.87, indicating that the remaining carbonate fractions in the dust particles range from 39-87%, respectively, even after the chemical aging times of 24-84 hrs. Several single particle chemical analysis studies with East Asian dust particles reached the same conclusions (Ro et al, 2005;Zhang et al, 2003;Zhang and Iwasaka, 1999). The replaced CO 3 2-fractions of 13-61% are believed to be released from dust particles by nitrate (and/ Surface roughness factor; 3) Values recommended by this study.…”

Section: Research and Theoretical Backgroundsupporting

confidence: 76%

“…HNO 3 levels of 1-3 ppb were frequently observed with high dust concentrations over the downwind areas from the polluted regions in East Asia (this will be discussed in more detail in section 2.4; also refer to Bauer et al (2004)). However, such large amounts of nitrate have never been found in dust particles, particularly in East Asia (Song et al, 2007;Ro et al, 2005;Song et al, 2005;Zhang et al, 2003). In contrast, when γ HNO 3 = = 10 -3 -10 -5 , R HNO 3 become much slower (τ 10 =3.1-91.8 days).…”

Section: Reaction Probability Of Hno 3 (γ γ Hno 3 )mentioning

confidence: 99%

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A Study on Three Factors Influencing Uptake Rates of Nitric Acid onto Dust Particles

Song¹,

Kim²

2011

Asian J. Atmos. Environ

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Recent studies have indicated that the observed nitric acid (HNO 3 ) uptake rates (R HNO 3 ) onto dust particles are much slower than R HNO 3 used in the previous modeling studies. Three factors that possibly affect R HNO 3 onto dust particles are discussed in this study:(1) the magnitude of reaction probability of HNO 3 (γ HNO 3 ), (2) aerosol surface areas, and (3) gas-phase HNO 3 mixing ratio. Through the discussion presented here, it is shown that the use of accurate γ HNO 3 is of primary importance. We suggest that the use of γ HNO 3 values between ~10-3 and ~10 -5 produces more realistic results than the use of γ HNO 3 values betweeñ 10 -1 and ~10 -2 does, more accurately modeling the nitrate formation characteristics on/in dust particles. We also discuss two different types of aerosol surface area, active and geometric, since the use of different aerosol surface areas often leads to an erroneous result in R HNO 3 . In addition, the levels of the gas-phase HNO 3 are investigated with the example cases of TRACE-P DC-8 flights in East Asia. The HNO 3 levels were found to be relatively high, indicating that they can not limit nitrate formation in dust particles.

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Section: Research and Theoretical Backgroundsupporting

confidence: 76%

Section: Reaction Probability Of Hno 3 (γ γ Hno 3 )mentioning

confidence: 99%

A Study on Three Factors Influencing Uptake Rates of Nitric Acid onto Dust Particles

Song¹,

Kim²

2011

Asian J. Atmos. Environ

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“…The net X-ray counts (= total counts -carbon-Formvar blank counts) of elements for each particle analysed were calculated, and their proportions were normalized to 100%. Although the elemental results were semiquantitative, the accuracy is sufficient to identify different particle types and to compare the differences in elemental ratios of the same particle type in different samples (Pósfai et al, 2003;Ebert et al, 2004;Niemi et al, 2005b;Ro et al, 2005;Laskin et al, 2006). The strong vacuum (∼10 −7 torr) and beam exposure causes evaporation of semivolatile compounds from particles, and for that reason, water, ammonium nitrate and organic compounds with high vapour pressure were lost, as is typical in electron microscopy.…”

Section: Tem/edx Individual Particle Analysesmentioning

confidence: 99%

Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

Niemi

Saarikoski

Tervahattu³

et al. 2006

Atmos. Chem. Phys.

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Abstract.Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode (PM 1 ∼16 µg m −3 , backward air mass trajectories from south-east), intermediate period (PM 1 ∼5 µg m −3 , backtrajectories from north-east) and clean period (PM 1 ∼2 µg m −3 , backtrajectories from northwest/north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM 0.2−1 and PM 1−3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM 0.2−1 samples were 1) soot and 2) (ammonium)sulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM 0.2−1 samples were 0-12% and 83-97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high (26-48%) in the PM 1−3.3 and PM 3.3−11 samples, while the PM 0.2−1 and PM 1−3.3 samples contained elevated proportions of silicates (22-33%), metal oxides/hydroxides (1-9%) and tar balls (1-4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM 1−3.3 samples contained mainly sea salt particles (67-89%) with a variable rate of Cl substitution (mainly by NO porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments (probably also biological origin) were highest in the PM 3.3−11 samples (0-81% and 0-22%, respectively). The origin of different particle types and the effect of aging processes on particle composition and their hygroscopic and optical properties are discussed.

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“…Ro et al (2005) reported components such as MgCO 3 , MgSO 4 , K 2 CO 3 , KNO 3 , and K 2 SO 4 in single-particle measurements of Asian dust sampled in Korea. The nitrate and sulfate components may have formed during transport via heterogeneous reactions with carbonates.…”

Section: Introductionmentioning

confidence: 99%

Influence of dust composition on cloud droplet formation

Kelly

Chuang

Wexler

2007

Atmospheric Environment

127

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Previous studies suggest that interactions between dust particles and clouds are significant; yet the conditions where dust particles can serve as cloud condensation nuclei (CCN) are uncertain. Since major dust components are insoluble, the CCN activity of dust strongly depends on the presence of minor components. However, many minor components measured in dust particles are overlooked in cloud modeling studies. Some of these compounds are believed to be products of heterogeneous reactions involving carbonates. In this study, we calculate with diameters between about 0.6 and 2 µm under some conditions. Dust particles > 2 µm often activate regardless of their composition. Only under very specialized conditions does the addition of a dust distribution into a rising parcel containing fine (NH 4 ) 2 SO 4 particles significantly reduce the total number of activated particles via water competition. Effects of dust on cloud saturation and droplet number via water competition are generally smaller than those reported previously for sea salt. Large numbers of fine dust CCN can significantly enhance the number of activated particles under certain conditions. Improved representations of dust mineralogy and reactions in global aerosol models could improve predictions of the effects of aerosol on climate.

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Single-Particle Characterization of Four “Asian Dust” Samples Collected in Korea, Using Low-Z Particle Electron Probe X-ray Microanalysis

Cited by 99 publications

References 35 publications

A Study on Three Factors Influencing Uptake Rates of Nitric Acid onto Dust Particles

A Study on Three Factors Influencing Uptake Rates of Nitric Acid onto Dust Particles

Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

Influence of dust composition on cloud droplet formation

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