Physico-chemical characteristics of dust aerosols deposited during the Soviet-American experiment (Tadzhikistan, 1989)

Andronova, A. V.; Gomès, L.; Смирнов, В. В.; Ivanov, A. V.; Shukurova, L. M.

doi:10.1016/0960-1686(93)90020-y

Cited by 32 publications

(18 citation statements)

References 15 publications

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“…The ART2a sorting algorithm split the dust particles into 23 particle clusters out of the 60 largest clusters, further evidence for the wide range of dust mineralogy at the single particle level. These Asian dust particles represent a complex mixture of numerous different minerals, as reported by previous studies (Andronova et al, 1993;Clarke et al, 2004;Gao and Anderson, 2001;Krueger et al, 2004;Pye, 1987;Trochkine et al, 2003;Yuan et al, 2004). The large fraction (>80%) of particles containing calcium marker ions (m/z +40, +56, +96) agrees with the high calcium carbonate fraction typical of Asian mineral dust (Jeong and Chun, 2006).…”

Section: Mineral Dust Mass Spectrasupporting

confidence: 67%

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Direct observations of the atmospheric processing of Asian mineral dust

et al. 2007

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Abstract. The accumulation of secondary acids and ammonium on individual mineral dust particles during ACEAsia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO 2 (g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing Correspondence to: K. Prather (kprather@ucsd.edu) state of dust with these secondary species validates previous mechanisms of the atmospheric processing of dust and generally agrees with simulated aerosol chemistry from the STEM-2K3 model. This series of novel results has important implications for improving the treatment of dust in global chemistry models and highlights a number of key processes that merit further investigation through laboratory and field studies.

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Section: Mineral Dust Mass Spectrasupporting

confidence: 67%

“…Ca was determined to be mostly from carbonate minerals including calcite (CaCO 3 ) and dolomite (CaMg(CO 3 ) 2 ). The fraction of carbonate in Asian dust has been reported to range from 1-12% by mass (Andronova et al, 1993;Derbyshire et al, 1998;Honda et al, 2004;Nishikawa et al, 2000 (Bruynseels and Van Grieken, 1983).…”

Section: Mineral Dust Mass Spectramentioning

confidence: 99%

Direct observations of the atmospheric processing of Asian mineral dust

et al. 2007

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“…Chemical analysis of the collected dust (Gomes and Gillette, 1993) showed a low iron content for Central Asian dust. A calcareous character and high contents of soluble salts were also observed (Miller-Schulze et al, 2011;Schettler et al, 2014;Groll et al, 2013;Andronova et al, 1993). In general, however, a very high variability lead to considerably different results depending on sampling location.…”

Section: Introductionmentioning

confidence: 88%

Long-term profiling of mineral dust and pollution aerosol with multiwavelength polarization Raman lidar at the Central Asian site of Dushanbe, Tajikistan: case studies

et al. 2017

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Abstract. For the first time, continuous vertically resolved aerosol measurements were performed by lidar in Tajikistan, Central Asia. Observations with the multiwavelength polarization Raman lidar Polly XT were conducted during CADEX (Central Asian Dust EXperiment) in Dushanbe, Tajikistan, from March 2015 to August 2016. Co-located with the lidar, a sun photometer was also operated. The goal of CADEX is to provide an unprecedented data set on vertically resolved aerosol optical properties in Central Asia, an area highly affected by climate change but largely missing vertically resolved aerosol measurements. During the 18-month measurement campaign, mineral dust was detected frequently from ground to the cirrus level height. In this study, an overview of the measurement period is given and four typical but different example measurement cases are discussed in detail. Three of them are dust cases and one is a contrasting pollution aerosol case. Vertical profiles of the measured optical properties and the calculated dust and non-dust mass concentrations are presented. Dust source regions were identified by means of backward trajectory analyses. A lofted layer of Middle Eastern dust with an aerosol optical thickness (AOT) of 0.4 and an extinction-related Ångström exponent of 0.41 was measured. In comparison, two near-ground dust cases have Central Asian sources. One is an extreme dust event with an AOT of 1.5 and Ångström exponent of 0.12 and the other one is a most extreme dust event with an AOT of above 4 (measured by sun photometer) and an Ångström exponent of −0.08. The observed lidar ratios (and particle linear depolarization ratios) in the presented dust cases range from 40.3 to 46.9 sr (and 0.18-0.29) at 355 nm and from 35.7 to 42.9 sr (0.31-0.35) at 532 nm wavelength. The particle linear depolarization ratios indicate almost unpolluted dust in the case of a lofted dust layer and pure dust in the near-ground dust cases. The lidar ratio values are lower than typical lidar ratio values for Saharan dust (50-60 sr) and comparable to Middle Eastern or west-Asian dust lidar ratios (35-45 sr). In contrast, the presented case of pollution aerosol of local origin has an Ångström exponent of 2.07 and a lidar ratio (particle linear depolarization ratio) of 55.8 sr (0.03) at 355 nm and 32.8 sr (0.08) at 532 nm wavelength.

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“…We explicitly treat the dissolution/precipitation of two carbonate minerals (i.e., calcite and magnesite). The most likely clay minerals for carbonates are calcite (CaCO 3 ) and dolomite (CaMg(CO 3 ) 2 ) (Andronova et al, 1993;Shao et al, 2007). Since the dissolution rate of dolomite is much faster than magnesite (MgCO 3 ), the dissolution rate of magnesium is thus controlled by the latter (Chou et al, 1989).…”

Section: Mineral Aerosol Dissolutionmentioning

confidence: 99%

Role of dust alkalinity in acid mobilization of iron

2010

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Abstract. Atmospheric processing of mineral aerosols by acid gases (e.g., SO 2 , HNO 3 , N 2 O 5 , and HCl) may play a key role in the transformation of insoluble iron (Fe in the oxidized or ferric (III) form) to soluble forms (e.g., Fe(II), inorganic soluble species of Fe(III), and organic complexes of iron). On the other hand, mineral dust particles have a potential of neutralizing the acidic species due to the alkaline buffer ability of carbonate minerals (e.g., CaCO 3 and MgCO 3 ). Here we demonstrate the impact of dust alkalinity on the acid mobilization of iron in a three-dimensional aerosol chemistry transport model that includes a mineral dissolution scheme. In our model simulations, most of the alkaline dust minerals cannot be entirely consumed by inorganic acids during the transport across the North Pacific Ocean. As a result, the inclusion of alkaline compounds in aqueous chemistry substantially limits the iron dissolution during the long-range transport to the North Pacific Ocean: only a small fraction of iron (<0.2%) dissolves from hematite in the coarse-mode dust aerosols with 0.45% soluble iron initially. On the other hand, a significant fraction of iron (1-2%) dissolves in the fine-mode dust aerosols due to the acid mobilization of the iron-containing minerals externally mixed with carbonate minerals. Consequently, the model quantitatively reproduces higher iron solubility in smaller particles as suggested by measurements over the Pacific Ocean. It implies that the buffering effect of alkaline content in dust aerosols might help to explain the inverse relationship between aerosol iron solubility and particle size. We also demonstrate that the iron solubility is sensitive to the chemical specification of iron-containing minerals in dust. Compared with the dust sources, soluble iron from combustion sources contributes to a relatively marginal effect for deCorrespondence to: A. Ito (akinorii@jamstec.go.jp) position of soluble iron over the North Pacific Ocean during springtime. Our results suggest that more comprehensive data for chemical specificity of iron-rich dust is needed to improve the predictive capability for size-segregated soluble iron particles.

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Physico-chemical characteristics of dust aerosols deposited during the Soviet-American experiment (Tadzhikistan, 1989)

Cited by 32 publications

References 15 publications

Direct observations of the atmospheric processing of Asian mineral dust

Direct observations of the atmospheric processing of Asian mineral dust

Long-term profiling of mineral dust and pollution aerosol with multiwavelength polarization Raman lidar at the Central Asian site of Dushanbe, Tajikistan: case studies

Role of dust alkalinity in acid mobilization of iron

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