Iron content and solubility in dust from high-alpine snow along a
                        north-south transect of High Asia

Wu, Guangjian; Zhang, Chenglong; Li, Zhongqin; Zhang, Xuelei; Gao, Shaopeng

doi:10.3402/tellusb.v64i0.17735

Cited by 11 publications

(10 citation statements)

References 41 publications

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“…4). Our data were similar to the previous reported iron contents in dust particles preserved in ice cores across the TP (Wu et al, 2012), which ranged from 3.38 % to 5.41 %. The iron in the cryoconite on the TP glaciers represents a natural background level.…”

Section: Abundance Of Elemental Fe (Total) and Free Fe (Iron Oxides)supporting

confidence: 92%

“…Compared to dust and BC, the composition and sources of organic matter over the glacier surface are complicated. Organic matter was a mixture of soil humic and humic-like matter, biogenic particles (e.g., algae, fungi and plant debris), and biomass/fossil fuel burning emissions (Wu et al, 2016), which are often termed brown carbon (BrC). Considering its diverse sources and complex composition, in this work we did not assume the specific optical parameters for organic matter.…”

Section: Contribution To Light Absorption By Cryoconite Componentsmentioning

confidence: 99%

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Iron oxides in the cryoconite of glaciers on the Tibetan Plateau: abundance, speciation and implications

et al. 2018

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Cryoconite is a mixture of impurities and ice visually represented by dark colors present in the ablation zone of glaciers. As an important constituent of light-absorbing impurities on the glacier surface, iron oxides influence the radiative properties of mineral dust and thus its impact on ice melting processes. In particular, the distinct optical properties between hematite and goethite (the major iron oxide species) highlight the necessity to obtain accurate knowledge about their abundance and geochemical behavior. Cryoconite samples from five glaciers in different regions of the Tibetan Plateau (TP) and surroundings were studied. The iron abundance in the cryoconite from TP glaciers ranged from 3.40 % to 4.90 % by mass, in accordance with typical natural background levels. Because the light absorption capacity of mineral dust essentially depends on the presence of iron oxides (i.e., free iron), iron oxides were extracted and determined using diffuse reflectance spectroscopy. The ratios of free to total iron for the five glaciers ranged from 0.31 to 0.70, emphasizing that iron in the form of oxides should be considered rather than total iron in the albedo and radiative modeling. Furthermore, the goethite content in iron oxides (in mass fraction) ranged from 81 % to 98 %, showing that goethite was the predominant form among the glaciers. Using the abundance and speciation of iron oxides as well as their optical properties, the total light absorption was quantitatively attributed to goethite, hematite, black carbon (BC) and organic matters at 450 and 600 nm wavelengths. We found that the goethite played a stronger role than BC at shorter wavelengths for most glaciers. Such findings were essential to understand the relative significance of anthropogenic and natural effects, and then taking the proper mitigation measures.

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Section: Abundance Of Elemental Fe (Total) and Free Fe (Iron Oxides)supporting

confidence: 92%

Section: Contribution To Light Absorption By Cryoconite Componentsmentioning

confidence: 99%

Iron oxides in the cryoconite of glaciers on the Tibetan Plateau: abundance, speciation and implications

et al. 2018

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“…Our data were similar to the previous reported iron contents in dust particles preserved in ice cores across Tibetan Plateau (Wu et al, 2012), which ranged from 3.38% to 5.41%. The iron in the cryoconite on the TP glaciers represents a natural background level.…”

Section: Abundance Of Elemental Fe (Total) and Free-fe (Iron Oxides)supporting

confidence: 92%

Iron oxides in the cryoconite on the glaciers over Tibetan Plateau: abundance, speciation and implications

Cong

Gao

Zhao

et al. 2018

Preprint

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Abstract.As an important constituent of light-absorbing impurities on the glacier surface, iron oxides determine the radiative impact of mineral dust. In particular, the distinct optical properties between hematite and goethite highlight the necessity to obtain accurate knowledge about their abundance and speciation. Cryoconite samples from five glaciers in different region of Tibetan Plateau (TP) and 20 surroundings were studied. The iron abundances in the cryoconite from TP glaciers ranged from 3.40% to 4.90% by mass, which reflected a natural background level. Iron oxides were extracted and determined using diffuse reflectance spectroscopy. The ratios of free to total iron for the five glaciers ranged from 0.31 to 0.70, emphasizing that iron in the form of oxides should be considered rather than total iron in the albedo and radiative modelling. Furthermore, the goethite content in iron oxides (in 25 mass fraction) ranged from 81% to 98%, showing that goethite is the predominant form among the glaciers. Using the abundance and speciation of iron oxides as well as their optical properties, the total light absorption were quantitatively attributed to goethite, hematite, black carbon and organic matters at 450 nm and 600 nm wavelengths. We found that the goethite played a stronger role than BC at shorter wavelength for most glaciers. Such findings are essential to understand the relative significance of 30 anthropogenic/natural effect, and then taking the proper mitigation measures.

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“…A previous study has revealed that the abundance of iron in ice core dust differs along the north-south transect of High Asia (Wu et al, 2012). In this study, new data from four ice cores in the central and western Tibetan Plateau are presented ( Table 1).…”

Section: Iron Abundance In Ice Core Dustmentioning

confidence: 90%

The visible spectroscopy of iron oxide minerals in dust particles from ice cores on the Tibetan Plateau

Xu²,

Zhang

et al. 2016

Tellus B: Chemical and Physical Meteorology

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Goethite (Gt) and hematite (Hm) are the most abundant forms of iron oxides in dust and the major light absorbers in the shortwave spectrum in air and snow. Diffuse reflectance spectrometry was performed to investigate the reflectance spectra of goethite and hematite in dust particles from ice cores, aerosol samples and glacier cryoconite on the northern and central Tibetan Plateau. The results showed that two peaks in the first derivative value of the spectra at 430 and 560 nm were determined to be goethite and hematite, respectively. The high iron content samples have a higher first derivative value, and prominent and much more distinct peaks for Hm and Gt. We propose that the strength of the Hm and Gt peaks may probe the iron content, and then in our samples hematite has a stronger correlation than goethite. However, when the iron content reaches a threshold, the iron oxides have little or no impact on the reflectance spectra. The fine fraction of glacier dust has a greater abundance of iron, and the first derivative values of hematite are higher than goethite, indicating that hematite might be concentrated in the fine fraction. The distinguishable differences in the Hm/Gt ratio among these ice core samples and other aerosol data indicate the regional to continental difference in composition, which can be used to simplify the iron oxides in snow radiation models.

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Iron content and solubility in dust from high-alpine snow along a north-south transect of High Asia

Cited by 11 publications

References 41 publications

Iron oxides in the cryoconite of glaciers on the Tibetan Plateau: abundance, speciation and implications

Iron oxides in the cryoconite of glaciers on the Tibetan Plateau: abundance, speciation and implications

Iron oxides in the cryoconite on the glaciers over Tibetan Plateau: abundance, speciation and implications

The visible spectroscopy of iron oxide minerals in dust particles from ice cores on the Tibetan Plateau

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