The solubility of ferric ion in marine mineral aerosol solutions at ambient relative humidities

Zhu, Xiaorong Ronald; Prospero, Joseph M.; Millero, Frank J.; Savoie, Dennis L.; Brass, Garrett W.

doi:10.1016/0304-4203(92)90069-m

Cited by 136 publications

(100 citation statements)

References 27 publications

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“…This cycling between cloud droplets and wet aerosol particles can occur several times [an average of 10 cycles throughout the troposphere (18)] before the aerosol drops to earth by wet or dry deposition. Thus, the chemical conditions within and between clouds are very different, with relatively high pH and low IS in cloud droplets and low pH and high IS in wet aerosols (20)(21)(22). This cycling was investigated for its effect on Fe dissolution in the atmosphere by Shi et al (23), who show that Fe is solubilized in wet aerosols and then reprecipitated as Fe nanoparticles in clouds.…”

Section: Significancementioning

confidence: 99%

Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans

Stockdale

Krom

Mortimer

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Acidification of airborne dust particles can dramatically increase the amount of bioavailable phosphorus (P) deposited on the surface ocean. Experiments were conducted to simulate atmospheric processes and determine the dissolution behavior of P compounds in dust and dust precursor soils. Acid dissolution occurs rapidly (seconds to minutes) and is controlled by the amount of H + ions present. For H + < 10 −4 mol/g of dust, 1-10% of the total P is dissolved, largely as a result of dissolution of surface-bound forms. At H + > 10 −4 mol/g of dust, the amount of P (and calcium) released has a direct proportionality to the amount of H + consumed until all inorganic P minerals are exhausted and the final pH remains acidic. Once dissolved, P will stay in solution due to slow precipitation kinetics. Dissolution of apatite-P (Ap-P), the major mineral phase in dust (79-96%), occurs whether calcium carbonate (calcite) is present or not, although the increase in dissolved P is greater if calcite is absent or if the particles are externally mixed. The system was modeled adequately as a simple mixture of Ap-P and calcite. P dissolves readily by acid processes in the atmosphere in contrast to iron, which dissolves more slowly and is subject to reprecipitation at cloud water pH. We show that acidification can increase bioavailable P deposition over large areas of the globe, and may explain much of the previously observed patterns of variability in leachable P in oceanic areas where primary productivity is limited by this nutrient (e.g., Mediterranean).atmospheric processing | ocean macronutrients | desert dusts

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Section: Significancementioning

confidence: 99%

Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans

Stockdale

Krom

Mortimer

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Zhu et al [1992] suggested that ferric ion solubility from hematite varies from a factor 10 13 when the pH varies from 1 to 8. [21] In addition, variations in pH during the experiments are a possibility.…”

Section: Factors Controlling the Solubilitymentioning

confidence: 99%

Dissolution of atmospheric iron in seawater

Bonnet¹

2004

Geophysical Research Letters

127

120

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In vitro dissolution experiments were conducted in seawater in order to quantify the partitioning between dissolved and particulate phases of iron associated to Saharan dust and urban particles. The percentage of iron released was very low (0.05 to 2.2%) depending on the particulate load, the aerosol source and the contact time. This percentage decreased with the amount of particles introduced following a power law, indicating that the process could be modeled. Indeed, these dissolution processes were a function of the lability of iron in relation to the particle source, the particle size and adsorption processes. According to these experiments, the dissolved iron induced in a 10 m mixed layer by Saharan events of various magnitudes ranges from 0.07 to 1 nM. Since these concentrations are in agreement with the natural iron requirements for the phytoplankton, such inputs can profoundly influence the primary production, especially in oligotrophic conditions.

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“…Thus although the iron-containing soil dust mobilized from arid regions supplies the majority of iron from the atmosphere to the oceans, the key flux in terms of the biogeochemical response to atmospheric deposition is the amount of soluble or bioavailable iron (Fung et al, 2000;Mahowald et al, 2009;Baker and Croot, 2010). It has been proposed that atmospheric processing of mineral aerosols by anthropogenic pollutants (mainly sulfuric acid formed from oxidation of SO 2 ) may transform insoluble iron into soluble forms (Zhu et al, 1992;Zhuang et al, 1992;Meskhidze et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…For instance, smaller particles could go through more thorough chemical processing due to a longer residence time in the atmosphere, which in turn results in higher solubility (Zhuang et al, 1992;Hand et al, 2004). In addition, cloud processing, which may involve radical reactions in liquid phase, has been suggested to increase the soluble iron particles in the fine mode (Zhu et al, 1992;Shi et al, 2009). The mineralogy of iron also influences the particulate iron solubility and may contribute to the size dependence of the soluble ironrich dust (Claquin et al, 1999;Cwiertny et al, 2008;Journet et al, 2008;Schroth et al, 2009).…”

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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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The solubility of ferric ion in marine mineral aerosol solutions at ambient relative humidities

Cited by 136 publications

References 27 publications

Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans

Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans

Dissolution of atmospheric iron in seawater

Role of dust alkalinity in acid mobilization of iron

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