Bioavailable iron production in airborne mineral dust: Controls by chemical composition and solar flux

Hettiarachchi, Eshani; Reynolds, Richard L.; Goldstein, Harland L.; Moskowitz, Bruce M.; Rubasinghege, Gayan

doi:10.1016/j.atmosenv.2019.02.037

Cited by 19 publications

(26 citation statements)

References 91 publications

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“…Because Fe 3+ shows low solubility above pH 3.6, it was determined that the conditions mentioned above most accurately simulated cloud processing of tropospheric aerosol particles that could drive iron mobility. , Under our experimental conditions, Fe 3+ above 60 ppm begins to precipitate as Fe(OH) 3 above pH 2.4 . Thus, an upper pH limit of 2.0 ± 0.1 allows for the measurement of Fe 3+ in solution without hydrolysis loss of iron .…”

Section: Methodsmentioning

confidence: 93%

“…Recent studies suggest that atmospheric processing of fly ash (FA), which are combustion particles emitted from coal-fired power plants, is an important source of soluble iron and an important parameter in the Earth’s climate system. − For example, in China, increasing annual emissions of FA are currently estimated to be in the range of 31 Tg, and in Europe, FA emission is estimated to be 90 Tg per year. − Given the particle size and morphology of FA, it can be transported from urban areas to remote regions of the oceans and can undergo atmospheric processing, impacting the atmospheric balance. , Similar to mineral dust, FA interacts with the highly acidic deliquescent layer formed around its particles by the uptake of water and acidic atmospheric gases (pH ≈ 0–3) . For mineral dust, the rate of iron dissolution depends not only on the pH but also on the mineralogy of the particles, the solar flux, and the identity of the acid. ,, One important atmospheric acid is nitric acid (HNO 3 ), primarily generated from nitrogen oxide atmospheric reactions. As an oxidizing acid, HNO 3 can impact the speciation of iron, while daytime conditions have shown to drive surface reactions of HNO 3 on semiconductors and chromophores present in these atmospheric aerosols .…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Kim

Xiao

Karchere-Sun

et al. 2020

ACS Earth Space Chem.

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Atmospheric combustion particles, such as fly ash emitted from coal-fired power plants, are a potential source of atmospheric iron, with significant implications in climate and global biogeochemical cycles. While the iron content and speciation of fly ash depend closely on the source region and combustion process, few studies have been carried out comparing the atmospheric processing of fly ash produced from coal-fired power plants in different regions. In this study, we present an investigation of iron dissolution in acidic aqueous solutions: HNO 3 and HCl at pH 1 and pH 2 under daytime and nighttime conditions for three fly ash samples from three different sources: United States (USFA), Central Europe (EUFA), and India fly ash (INFA). Iron mobility and speciation depend on the source region and the combustion efficiency that generates fly ash. In HCl suspensions, proton-promoted mechanisms lead to larger fractions of aqueous-phase iron leached from fly ash particles, with poorly combusted samples providing significant fractions of Fe 2+ . In HNO 3 suspensions, a surface-mediated redox reaction suppresses the mobility of Fe 2+ , leading to the formation of nitrites. In the presence of solar radiation, previously unrecognized pathways of atmospheric processing enhance the formation Fe 2+ and nitrous acid from combustion particles. The information provided herein could be significant to increase our understanding of the effects of combustion particles in the atmospheric chemical balance regarding iron and nitrites.

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Section: Methodsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Kim

Xiao

Karchere-Sun

et al. 2020

ACS Earth Space Chem.

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“…Icelandic dust has comparable amorphous Fe (FeA) content to North African dust, but higher magnetite and lower goethite and hematite (FeD) content. Existing observations show that the magnetite content in African dust is generally below 0.1 wt% or not detectable (Hettiarachchi et al, 2019;Lazaro et al, 2008;Moskowitz et al, 2016). Moskowitz et al (2016) reported 0.6 wt% magnetite in surface sediments (PM63) collected in proximity of the Tibesti volcanic based on magnetic measurements.…”

Section: Comparison Of Icelandic Dust With North African and Asian Dustmentioning

confidence: 99%

Distinct chemical and mineralogical composition of Icelandic dust compared to North African and Asian dust

Baldo¹,

Formenti²,

Nowak³

et al. 2020

Preprint

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Abstract. Iceland is a highly active source of natural dust. Icelandic dust has the potential to affect directly the climate via dust-radiation interaction, and indirectly via dust-cloud interaction, snow/ice albedo effect and impacts on biogeochemical cycles. The impacts of Icelandic dust depend on its mineralogical and chemical composition. However, lack of data has prevented an accurate assessment of the role of Icelandic dust in the Earth system. Here, we collected surface sediment samples from five major Icelandic dust hotspots. Dust aerosols were generated and suspended in atmospheric chambers, and PM10 and PM20 fractions were collected for further analysis. We found that the dust samples primarily consist of amorphous basaltic material ranging from 8 wt% (from the Hagavatn hotspot) to 60–90 wt% (other hotspots). Samples had relatively high total Fe content (10–13 wt%). Sequential extraction of Fe to determine its chemical form shows that dithionite Fe (Fe oxides such as hematite and goethite) and ascorbate Fe (amorphous Fe) contribute respectively 1–6 %, and 0.3–1.4 % of the total Fe in Icelandic dust. The magnetite fraction is 7–15 % of total Fe and 1–2 wt% of PM10, which is orders of magnitude higher than in mineral dust from North Africa. Nevertheless, about 80–90 % of the Fe is contained in pyroxene and amorphous glass. The initial Fe solubility (ammonium acetate extraction at pH 4.7) is from 0.08–0.6 %, which is comparable to low latitude dust such as that from North Africa. The Fe solubility at low pH (i.e., 2) is significantly higher than typical low latitude dust (up to 30 % at pH 2 after 72 hrs). Our results revealed the fundamental differences in composition and mineralogy of Icelandic dust from low latitude dust. We attribute these differences to the low degree of chemical weathering, the basaltic composition of the parent sediments, and glacial processes. Icelandic dust contributes to the atmospheric deposition of soluble Fe and can impact primary productivity in the North Atlantic Ocean. The distinct chemical and mineralogical composition, particularly the high magnetite content (1–2 wt%), indicates a potentially significant impact of Icelandic dust on the radiation balance in the sub-polar and polar regions.

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“…Because of their relatively small size (2 nm to 10 μm), atmospheric aerosols have little inertia and can remain suspended for several days, resulting in long‐range transport and significant impact in the chemical balance of the atmosphere. [ 1,2 ] In fact, recent laboratory and modeling studies have shown that PM has important implications in biogeochemical cycles, [ 3–10 ] heavy‐metal transport, [ 11,12 ] cloud nucleation, [ 13–17 ] and heterogeneous reactions, [ 18–26 ] among other direct or indirect impacts.…”

Section: Introductionmentioning

confidence: 99%

Particle formation and surface processes on atmospheric aerosols: A review of applied quantum chemical calculations

Leonardi

Ricker

Gale

et al. 2020

Int J of Quantum Chemistry

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Aerosols significantly influence atmospheric processes such as cloud nucleation, heterogeneous chemistry, and heavy-metal transport in the troposphere. The chemical and physical complexity of atmospheric aerosols results in large uncertainties in their climate and health effects. In this article, we review recent advances in scientific understanding of aerosol processes achieved by the application of quantum chemical calculations. In particular, we emphasize recent work in two areas: new particle formation and heterogeneous processes. Details in quantum chemical methods are provided, elaborating on computational models for prenucleation, secondary organic aerosol formation, and aerosol interface phenomena. Modeling of relative humidity effects, aerosol surfaces, and chemical kinetics of reaction pathways is discussed. Because of their relevance, quantum chemical calculations and field and laboratory experiments are compared. In addition to describing the atmospheric relevance of the computational models, this article also presents future challenges in quantum chemical calculations applied to aerosols.

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Bioavailable iron production in airborne mineral dust: Controls by chemical composition and solar flux

Cited by 19 publications

References 91 publications

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Distinct chemical and mineralogical composition of Icelandic dust compared to North African and Asian dust

Particle formation and surface processes on atmospheric aerosols: A review of applied quantum chemical calculations

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