Quantification of iron oxides in desert aerosol

Lafon, S.; Rajot, Jean-Louis; Alfaro, Stéphane C.; Gaudichet, A.

doi:10.1016/j.atmosenv.2003.11.006

Cited by 139 publications

(135 citation statements)

References 32 publications

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“…While Alfaro et al (2004) found in their dust samples comparable total iron contents in the range of 3.0 to 6.5 wt-%, they assigned the significant amount of 2.8 to 5.8 wt-% of this iron to be present in iron oxide phases. However their iron oxide content was determined with the method by Lafon et al (2004) as the difference between total iron and its structural fraction. Structural fraction in this case quantifies the remaining iron content after applying an adapted reductive extraction method as commonly used in soil science .…”

Section: Discussionmentioning

confidence: 99%

Optical properties and mineralogical composition of different Saharan mineral dust samples: a laboratory study

Linke¹,

Möhler²,

et al. 2006

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Abstract. In aerosol chamber experiments optical properties of resuspended mineral dust samples of defined size distributions were measured. Extinction coefficients (b ext ) and mass specific extinction cross sections (σ ext ) were determined for Saharan dust samples from different locations. The results for σ ext were not very sensitive to the type of dust and varied at λ=550 nm between 3.3±0.4 m 2 g −1 and 3.7±0.4 m 2 g −1 .The absorption coefficients (b abs ) and mass specific absorption cross sections (σ abs ) were determined with a novel multiwavelength photo-acoustic absorption spectrometer (PAS). The single scattering albedo was close to 1 (0.98 to 0.99) at 532 nm and 1064 nm, but significantly lower (0.63 to 0.76) at 266 nm. Additionally the chemical and mineralogical composition of the dust samples were analysed with special regard to the iron oxide phases hematite and goethite. At λ=266 nm the mineral dust sample without any detectable iron oxides showed a significantly higher SSA compared to the sample with a hematite content of 0.6 wt-%.

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Section: Discussionmentioning

confidence: 99%

Optical properties and mineralogical composition of different Saharan mineral dust samples: a laboratory study

Linke¹,

Möhler²,

et al. 2006

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“…The iron oxides-to-total iron ratio for the analysed samples varied between 0.4 and 0.61, accounting for between 1% and 3% of the total gravimetric mass. According to Lafon et al (2004Lafon et al ( , 2006, iron oxides were considered in internal mixing with clays. The volume fractions of the iron oxides into the clay-iron oxide aggregates are reported in Table V.…”

Section: Characterization Of Mineral Dust: Physicochemical and Opticamentioning

confidence: 99%

“…Iron oxide content relevant to light-absorption in the visible spectrum (Sokolik and Toon, 1999) was measured with the adapted CBD method developed by Lafon et al (2004). This method is an adaptation for aerosol filters (mass smaller than 500 µg) of the classical method of Mehra and Jackson (1960) for soil analysis.…”

Section: Iron Oxide Contentmentioning

confidence: 99%

Physico‐chemical and optical properties of Sahelian and Saharan mineral dust: in situ measurements during the GERBILS campaign

Klaver

Formenti

Caquineau

et al. 2011

Quart J Royal Meteoro Soc

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Regardless of origin, clays (illite, kaolinite) dominated the total volume (79-90%); the remainder was composed of quartz, calcium-rich minerals (calcite, dolomite, gypsum) and alkali feldspars. Iron oxides, measured using a selective chemical extraction method, accounted for 1-3% of the total dust mass. The dependence of particle number size and shape distribution on the origin of dust seems minor too, although our results might be slightly misleading due to the fact that those kinds of data have been gathered on flights when dust had comparable origins and residence time.Mineral dust is only weakly absorbing in the mid-visible wavelengths (single scattering albedo ω 0 > 0.95 at 550 nm), and ω 0 measured values can be reproduced by measuring the bulk fractions of the major minerals, i.e. clays, quartz, calcite and iron oxides. At this wavelength, knowledge of the nature of clays and iron oxides, or the state of mixing of the minerals, does not induce significant differences in the results. A more precise description of the nature of clays and iron oxides is necessary at lower wavelengths owing to larger differences in their spectral optical properties. In particular, knowledge of the nature of the dominant clay is important for determining light scattering in the backward hemisphere.

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“…Guieu et al (2002) showed that the average observed total iron originating from Tunisia, Morocco, Niger and Algeria is 4.45 %. Lafon et al (2004) reported that the total iron ranges from 6.2 to 8.7 % in Saharan and Sahelian samples. Other observations indicate that the total iron in samples collected in the Sahara and the Sahel is in the range of 0.8-12.2 % (Shi et al, 2011a).…”

Section: Total Iron Distribution In Soil and Decay Ratesmentioning

confidence: 99%

“…Furthermore, a transport equation for the free iron (the goethite and hematite content) was introduced as one of the model governing equations to parameterize the soluble iron chemical reaction as a function of the mineralogy at the dust sources. We followed here the classification of iron-containing minerals to (i) structural iron embedded in the crystal lattice of aluminosilicates and (ii) iron in oxide/hydroxide called "free-iron" (Lafon et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric processing of iron carried by mineral dust

2013

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Nutrification of the open ocean originates mainly from deposited aerosol in which the bio-avaliable iron is likely to be an important factor. The relatively insoluble iron in dust from arid soils becomes more soluble after atmospheric processing and, through its deposition in the ocean, could contribute to marine primary production. To numerically simulate the atmospheric route of iron from desert sources to sinks in the ocean, we developed a regional atmospheric dust-iron model that included parameterization of the transformation of iron to a soluble form caused by dust mineralogy, cloud processes and solar radiation. When compared with field data on the aerosol iron, which were collected during several Atlantic cruises, the results from the higher-resolution simulation experiments showed that the model was capable of reproducing the major observed patterns

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Quantification of iron oxides in desert aerosol

Cited by 139 publications

References 32 publications

Optical properties and mineralogical composition of different Saharan mineral dust samples: a laboratory study

Optical properties and mineralogical composition of different Saharan mineral dust samples: a laboratory study

Physico‐chemical and optical properties of Sahelian and Saharan mineral dust: in situ measurements during the GERBILS campaign

Atmospheric processing of iron carried by mineral dust

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