Non-metal redox kinetics: hypobromite and hypobromous acid reactions with iodide and with sulfite and the hydrolysis of bromosulfate

Troy, Robert C.; Margerum, Dale W.

doi:10.1021/ic00018a028

Cited by 154 publications

(126 citation statements)

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“…Aqueous-phase oxidation of S(IV) by halogens (HOBr and HOCl) has been suggested to be important in the marine boundary layer (Vogt et al, 1996;von Glasow et al, 2002). However, this suggestion is based on the assumption that the rate constants for the reactions HSO − 3 +HOBr/HOCl are equal to the rate constants for SO 2− 3 + HOBr/HOCl, because only the latter has been measured (Fogelman et al, 1989;Troy and Margerum, 1991). This assumption represents a large source of uncertainty because HSO − 3 is the dominant aqueous S(IV) species under typical cloud water pH (2-7) conditions.…”

Section: Oxygen Isotopic Composition Of Sulfatementioning

confidence: 99%

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ17O(SO42–)

2011

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Abstract. We use a global three-dimensional chemical transport model to quantify the influence of anthropogenic emissions on atmospheric sulfate production mechanisms and oxidant concentrations constrained by observations of the oxygen isotopic composition ( ). Additional model simulations are conducted to explore the sensitivity of the oxygen isotopic composition of sulfate to uncertainties in the preindustrial emissions of oxidant precursors.

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Section: Oxygen Isotopic Composition Of Sulfatementioning

confidence: 99%

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ17O(SO42–)

2011

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“…Oxidation by HOBr is faster, however HOCl is likely to be the more important oxidant due to the relative abundances of Br and Cl (Troy and Margerum, 1991). von Glasow et al (2002) modelled oxidation in the MBL and found that under almost all conditions, HOCl -not O 3 -was the dominant oxidant for SO 2 .…”

Section: E Harris Et Al: Sulfur Isotope Fractionation During Oxidatmentioning

confidence: 99%

“…10) on HOCl, which results in Cl + transfer to form ClSO − 3 (Yiin and Margerum, 1988). Hydrolysis of chlorosulfuric acid to form sulfate, H + and Cl − is the rate-limiting step, thus the aerosol will not be acidified as rapidly as with other oxidation mechanisms (Yiin and Margerum, 1988;Fogelman et al, 1989;Troy and Margerum, 1991), which may partially explain the very high reactive uptake coefficient. Irradiation could speed up the hydrolysis of ClSO − 3 , decreasing the reactive uptake coefficient.…”

Section: Sulfate Production Rate During Aqueous Oxidation In Dropletsmentioning

confidence: 99%

Fractionation of sulfur isotopes during heterogeneous oxidation of SO2 on sea salt aerosol: a new tool to investigate non-sea salt sulfate production in the marine boundary layer

et al. 2012

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Abstract. The oxidation of SO 2 to sulfate on sea salt aerosols in the marine environment is highly important because of its effect on the size distribution of sulfate and the potential for new particle nucleation from H 2 SO 4 (g). However, models of the sulfur cycle are not currently able to account for the complex relationship between particle size, alkalinity, oxidation pathway and rate -which is critical as SO 2 oxidation by O 3 and Cl catalysis are limited by aerosol alkalinity, whereas oxidation by hypohalous acids and transition metal ions can continue at low pH once alkalinity is titrated. We have measured 34 S/ 32 S fractionation factors for SO 2 oxidation in sea salt, pure water and NaOCl aerosol, as well as the pH dependency of fractionation.Oxidation of SO 2 by NaOCl aerosol was extremely efficient, with a reactive uptake coefficient of ≈0.5, and produced sulfate that was enriched in 32 S with α OCl = 0.9882±0.0036 at 19 • C. Oxidation on sea salt aerosol was much less efficient than on NaOCl aerosol, suggesting alkalinity was already exhausted on the short timescale of the experiments. Measurements at pH = 2.1 and 7.2 were used to calculate fractionation factors for each step from SO 2 (g) → multiple steps → SO 2− 3 . Oxidation on sea salt aerosol resulted in a lower fractionation factor than expected for oxidation of SO 2− 3 by O 3 (α seasalt = 1.0124±0.0017 at 19 • C). Comparison of the lower fractionation during oxidation on sea salt aerosol to the fractionation factor for high pH oxidation shows HOCl contributed 29 % of S(IV) oxidation on sea salt in the short experimental timescale, highlighting the potential importance of hypohalous acids in the marine environment.The sulfur isotope fractionation factors measured in this study allow differentiation between the alkalinity-limited pathways -oxidation by O 3 and by Cl catalysis (α 34 = 1.0163 ± 0.0018 at 19 • C in pure water or 1.0199 ± 0.0024 at pH = 7.2) -which favour the heavy isotope, and the alkalinity non-limited pathways -oxidation by transition metal catalysis (α 34 = 0.9905±0.0031 at 19 • C, Harris et al., 2012a) and by hypohalites (α 34 = 0.9882±0.0036 at 19 • C) -which favour the light isotope. In combination with field measurements of the oxygen and sulfur isotopic composition of SO 2 and sulfate, the fractionation factors presented in this paper may be capable of constraining the relative importance of different oxidation pathways in the marine boundary layer.

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“…Only the rate constant for reaction (23a) has been measured (Troy and Margerum, 1991). Assuming that reaction (23b) proceeds at the same rate, Vogt et al (1996) found that it can contribute about 20% to S(IV) oxidation.…”

Section: Modeling the Mechanism Of Bromine Chemistry In The Mblmentioning

confidence: 99%

Inorganic bromine in the marine boundary layer: a critical review

et al. 2003

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Abstract. The cycling of inorganic bromine in the marine boundary layer (mbl) has received increased attention in recent years. Bromide, a constituent of sea water, is injected into the atmosphere in association with sea-salt aerosol by breaking waves on the ocean surface. Measurements reveal that supermicrometer sea-salt aerosol is substantially depleted in bromine (often exceeding 50%) relative to conservative tracers, whereas marine submicrometer aerosol is often enriched in bromine. Model calculations, laboratory studies, and field observations strongly suggest that the supermicrometer depletions reflect the chemical transformation of particulate bromide to reactive inorganic gases that influence the processing of ozone and other important constituents of marine air. Mechanisms for the submicrometer enrichments are not well understood. Currently available techniques cannot reliably quantify many Br-containing compounds at ambient concentrations and, consequently, our understanding of inorganic Br cycling over the oceans and its global significance are uncertain. To provide a more coherCorrespondence to: R. Sander (sander@mpch-mainz.mpg.de) ent framework for future research, we have reviewed measurements in marine aerosol, the gas phase, and in rain. We also summarize sources and sinks, as well as model and laboratory studies of chemical transformations. The focus is on inorganic bromine over the open oceans outside the polar regions. The generation of sea-salt aerosol at the ocean surface is the major tropospheric source producing about 6.2 Tg/a of bromide. The transport of Br from continents (as mineral aerosol, and as products from biomass-burning and fossil-fuel combustion) can be of local importance. Transport of degradation products of long-lived Br-containing compounds from the stratosphere and other sources contribute lesser amounts. Available evidence suggests that, following aerosol acidification, sea-salt bromide reacts to form Br 2 and BrCl that volatilize to the gas phase and photolyze in daylight to produce atomic Br and Cl. Subsequent transformations can destroy tropospheric ozone, oxidize dimethylsulfide (DMS) and hydrocarbons in the gas phase and S(IV) in aerosol solutions, and thereby potentially influence climate. Inorganic bromine in the mbl gas phase during daytime are consistent with expectations based on photochemistry. We expect that the importance of inorganic Br cycling will vary in the future as a function of both increasing acidification of the atmosphere (through anthropogenic emissions) and climate changes. The latter affects bromine cycling via meteorological factors including global wind fields (and the associated production of sea-salt aerosol), temperature, and relative humidity.

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Non-metal redox kinetics: hypobromite and hypobromous acid reactions with iodide and with sulfite and the hydrolysis of bromosulfate

Cited by 154 publications

References 3 publications

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ<sup>17</sup>O(SO<sub>4</sub><sup>2–</sup>)

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ<sup>17</sup>O(SO<sub>4</sub><sup>2–</sup>)

Fractionation of sulfur isotopes during heterogeneous oxidation of SO<sub>2</sub> on sea salt aerosol: a new tool to investigate non-sea salt sulfate production in the marine boundary layer

Inorganic bromine in the marine boundary layer: a critical review

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Non-metal redox kinetics: hypobromite and hypobromous acid reactions with iodide and with sulfite and the hydrolysis of bromosulfate

Cited by 154 publications

References 3 publications

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ&lt;sup&gt;17&lt;/sup&gt;O(SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2–&lt;/sup&gt;)

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ&lt;sup&gt;17&lt;/sup&gt;O(SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2–&lt;/sup&gt;)

Fractionation of sulfur isotopes during heterogeneous oxidation of SO&lt;sub&gt;2&lt;/sub&gt; on sea salt aerosol: a new tool to investigate non-sea salt sulfate production in the marine boundary layer

Inorganic bromine in the marine boundary layer: a critical review

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The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ<sup>17</sup>O(SO<sub>4</sub><sup>2–</sup>)

The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ<sup>17</sup>O(SO<sub>4</sub><sup>2–</sup>)

Fractionation of sulfur isotopes during heterogeneous oxidation of SO<sub>2</sub> on sea salt aerosol: a new tool to investigate non-sea salt sulfate production in the marine boundary layer