Size-resolved chemical composition of Australian dust aerosol during winter

Radhi, M.; Box, Michael A.; Box, G. P.; Keywood, Melita; Cohen, David D.; Stelcer, Eduard; Mitchell, Rosalind

doi:10.1071/en10134

Cited by 16 publications

(12 citation statements)

References 36 publications

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“…[38] According to the literature, a ratio of more than 0.3 indicates a desert origin. [44,45] A previous study on the Lake Eyre Basin [39,40,46] supports the hypothesis of the dust origin. This suggests that the particles originated from the inland of Australia and travelled a long distance.…”

Section: Resultssupporting

confidence: 68%

Unusual Sydney dust storm and its mineralogical and organic characteristics

et al. 2012

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Environmental context. In 2009, at the end of the longest drought period ever recorded in Australia, a major dust storm blanketed the cities of Sydney and Brisbane for more than 24 h. The source of the dust was inner New South Wales and South Australia, where large scale open-cut mining occurs together with agricultural practices. We report results of extensive mineralogical and chemical analyses of the dust, and discuss their significance in terms of the dust origins and potential human health risks.Abstract. In a 24-h period from 23 to 24 September 2009, a dust storm passed over Sydney, Australia that produced a red sky and reduced the visibility to a few metres. It was Sydney's worst dust storm since 1942. During this period, the PM 10 (particles measuring 10 mm or less) value jumped from 50 to 11 800 mg m À3 . The dust storm was sampled and its mineralogical and organic contents were analysed. Four major particle sizes (0.6, 4.5, 9.3 and 20 mm) were observed in the dust. A multimodal particle distribution indicated a long range of dust transport. Mineralogical analysis showed that the particles were mainly composed of crustal elemental oxides of Al and Si. The ratio of Al/Si was 0.39 and the organic content was 10.6 %, which was found to be enriched with humic-type substances. The high Al/Si ratio (.0.3) indicated that the dust originated from desert land whereas the high organic content indicated that the particles were also derived from eroded agricultural land. A fluorescence spectroscopic study on the organic matter at excitation and emission wavelengths of 245-265 and 330-350 nm indicated that biohazardous substances were unlikely to be present in the dust.

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Section: Resultssupporting

confidence: 68%

Unusual Sydney dust storm and its mineralogical and organic characteristics

et al. 2012

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“…Being further from the coast, Lake Argyle is less likely to be noticeably affected by sea salt. However, it should be noted that Radhi et al (2011) found significant sea salt levels in one of their Daily and monthly mean values of AOT 500 .…”

Section: Daily and Monthly Datamentioning

confidence: 89%

Biomass-burning aerosol over northern Australia

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Box²,

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et al. 2012

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“…For samples from areas other than northern Africa, the largest variability is observed for the Fe / Ca values, ranging from 0.1 to 8, whereas the Si / Al ratio varied only between 2.5 and 4.8. In this case, values are available in the literature for comparison (e.g., Cornille et al, 1990;Reid et al, 1994;Eltayeb et al, 2001;Lafon et al, 2006;Shen et al, 2007;Radhi et al, 2010Radhi et al, , 2011Formenti et al, 2011Formenti et al, , 2014aScheuvens et al, 2013, and references within). Values in the PM 2.5 fraction are very consistent with those obtained in the PM 10.6 : their linear correlation has a slope of 1.03 (±0.05) and a R 2 equal to 0.97, suggesting that the elemental composition is relatively size independent.…”

Section: Elemental Composition and Iron Oxide Contentmentioning

confidence: 99%

Spectral- and size-resolved mass absorption efficiency of mineral dust aerosols in the shortwave spectrum: a simulation chamber study

et al. 2017

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Abstract. This paper presents new laboratory measurements of the mass absorption efficiency (MAE) between 375 and 850 nm for 12 individual samples of mineral dust from different source areas worldwide and in two size classes: PM 10.6 (mass fraction of particles of aerodynamic diameter lower than 10.6 µm) and PM 2.5 (mass fraction of particles of aerodynamic diameter lower than 2.5 µm). The experiments were performed in the CESAM simulation chamber using mineral dust generated from natural parent soils and included optical and gravimetric analyses.The results show that the MAE values are lower for the PM 10.6 mass fraction (range 37-135 × 10 −3 m 2 g −1 at 375 nm) than for the PM 2.5 (range 95-711 × 10 −3 m 2 g −1 at 375 nm) and decrease with increasing wavelength as λ −AAE , where the Ångström absorption exponent (AAE) averages between 3.3 and 3.5, regardless of size. The size independence of AAE suggests that, for a given size distribution, the dust composition did not vary with size for this set of samples. Because of its high atmospheric concentration, light absorption by mineral dust can be competitive with black and brown carbon even during atmospheric transport over heavy polluted regions, when dust concentrations are significantly lower than at emission. The AAE values of mineral dust are higher than for black carbon (∼ 1) but in the same range as light-absorbing organic (brown) carbon. As a result, depending on the environment, there can be some ambiguity in apportioning the aerosol absorption optical depth (AAOD) based on spectral dependence, which is relevant to the development of remote sensing of light-absorbing aerosols and their assimilation in climate models. We suggest that the sample-to-sample variability in our dataset of MAE values is related to regional differences in the mineralogical composition of the parent soils. Particularly in the PM 2.5 fraction, we found a strong linear correlation between the dust lightPublished by Copernicus Publications on behalf of the European Geosciences Union. 7176 L. Caponi et al.: Spectral-and size-resolved mass absorption efficiency of mineral dust aerosols absorption properties and elemental iron rather than the iron oxide fraction, which could ease the application and the validation of climate models that now start to include the representation of the dust composition, as well as for remote sensing of dust absorption in the UV-vis spectral region.

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Size-resolved chemical composition of Australian dust aerosol during winter

Cited by 16 publications

References 36 publications

Unusual Sydney dust storm and its mineralogical and organic characteristics

Unusual Sydney dust storm and its mineralogical and organic characteristics

Biomass-burning aerosol over northern Australia

Spectral- and size-resolved mass absorption efficiency of mineral dust aerosols in the shortwave spectrum: a simulation chamber study

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