Halogens and their role in polar boundary-layer ozone depletion

Simpson, W. R.; Glasow, R. von; Riedel, Katja; Anderson, P. S.; Ariya, Parisa A.; Bottenheim, J. W.; Burrows, J. P.; Carpenter, Lucy J.; Frieß, Udo; Goodsite, Michael Evan; Heard, D. E.; Hutterli, Manuel A.; Jacobi, Hans-Werner; Kaleschke, Lars; Neff, Basil; Plane, J. M. C.; Platt, U.; Richter, Andreas; Roscoe, H. K.; Sander, R.; Shepson, P. B.; Sodeau, John R.; Steffen, Alexandra; Wagner, T.; Wolff, Eric

doi:10.5194/acpd-7-4285-2007

Cited by 190 publications

(328 citation statements)

References 268 publications

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“…Nevertheless, so far no IO has been reliably observed in the Arctic. ClO was detected at levels up to 21 pmol/mol (8), but typically maximum values of around 1-2 pmol/mol are estimated (7). Simultaneous observations in the Arctic of Br 2 and BrCl of up to 27 pmol/mol and 35 pmol/mol, respectively, also indicate the presence of Chlorine (15).…”

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confidence: 96%

“…Satellite observations from GOME (Global Ozone Monitoring Experiment) show enhanced BrO concentrations largely to be present over first-year sea ice in comparison to multiyear sea ice, likely due to the higher salinity of the former (16,17). The release of halogens from sea salt is a complex process (18,19), which is not completely understood (7). Accurate measurements of the involved trace gases are required to improve our understanding of these processes.…”

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confidence: 99%

“…Accurate measurements of the involved trace gases are required to improve our understanding of these processes. Halogens are also involved in the almost complete oxidation and deposition of tropospheric gaseous elementary mercury (20), in the alteration of oxidation fates for volatile organic compounds, and in the export of bromine into the free troposphere (7).…”

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confidence: 99%

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Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

Pöhler

Vogel

Frieß

et al. 2010

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

117

136

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In the polar tropospheric boundary layer, reactive halogen species (RHS) are responsible for ozone depletion as well as the oxidation of elemental mercury and dimethyl sulphide. After polar sunrise, air masses enriched in reactive bromine cover areas of several million square kilometers. Still, the source and release mechanisms of halogens are not completely understood. We report measurements of halogen oxides performed in the Amundsen Gulf, Arctic, during spring 2008. Active long-path differential optical absorption spectroscopy (LP-DOAS) measurements were set up offshore, several kilometers from the coast, directly on the sea ice, which was never done before. High bromine oxide concentrations were detected frequently during sunlight hours with a characteristic daily cycle showing morning and evening maxima and a minimum at noon. The, so far, highest observed average mixing ratio in the polar boundary layer of 41 pmol/mol (equal to pptv) was detected. Only short sea ice contact is required to release high amounts of bromine. An observed linear decrease of maximum bromine oxide levels with ambient temperature during sunlight, between −24°C and −15°C, provides indications on the conditions required for the emission of RHS. In addition, the data indicate the presence of reactive chlorine in the Arctic boundary layer. In contrast to Antarctica, iodine oxide was not detected above a detection limit of 0.3 pmol/mol.halogen chemistry | ozone depletion | bromine explosion | polar | DOAS T he depletion of the stratospheric ozone layer due to reactive halogen species is well known. Similarly, ozone depletion events (ODEs) in the polar boundary layer, arising after sunrise, were discovered in the 1980s (1, 2, 3). These events were found to be related to high concentrations of filterable bromine. It was therefore proposed that ozone could be destroyed by catalytic reaction cycles involving bromine atoms (Br) and bromine monoxide (BrO) (4).The initial reaction is the release of Br 2 from the liquid to the gas phase and the photolysis to Br, which will lead to a quick oxidation to BrO by destroying an ozone molecule. Note that there is always some production of Br atoms from the photochemical degradation of CH 3 Br, which is ubiquitous in the atmosphere. Bromine atoms are recycled from BrO by different processes. The most important recycling is the BrO self-reaction (R 2·BrO ) with the total rate constant k 2·BrO ¼ 3.2 × 10 −12 cm 3 molec −1 s −1 (5) producing Br atoms or Br 2 . During daylight, Br 2 is again photolyzed to Br, thus all channels of R 2·BrO lead to a net loss of O 3 . Overall, reactive bromine (Br and BrO) acts as a catalyst for ozone destruction. An autocatalytic release of bromine from the sea salt surface ice, the so-called "bromine explosion" (6), supplies sufficient bromine to the gas phase. A simplified overview on bromine release mechanisms and ozone destruction cycles is given in Fig. 1 (for a recent review see 7).The key role of bromine was first confirmed by long-path differential optical absorption ...

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confidence: 96%

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confidence: 99%

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confidence: 99%

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Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

Pöhler

Vogel

Frieß

et al. 2010

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

117

136

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“…Sites with a high snow accumulation rate provide well resolved records of recent decades, while sites with a low snow accumulation rate offer low-resolution reconstructions of concentrations over much longer timescales. Some artefacts do occur for CO 2 for Greenland ice that has high concentrations of impurities such as organic matter and carbonate-rich dust, so that Antarctic cores are preferred for this gas. For CH 4 , ice cores from both Greenland andAntarctica show identical patterns of change in concentration over both short and long timescales, but with a gradient in concentrations between the hemispheres that is expected from the modern distribution of concentrations (and that derives from the predominance of northern sources).…”

Section: Stable Trace Gasesmentioning

confidence: 99%

Past atmospheric composition and chemistry from ice cores - progress and prospects

2007

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Environmental context. Investigating the past is often the only way we have of determining whether we have included all processes correctly into models, and then of verifying their behaviour. Ice cores provide an excellent way of finding out about the past. Air bubbles trapped in the ice allow us to directly access the concentration of stable trace gases, including important greenhouse gases. However, there are also tantalising possibilities to learn about aerosols and shorter-lived gases. This article describes some of the information we have already learnt from ice cores, but also describes the challenges that require understanding of atmospheric chemistry in the polar regions today in order to extract the full value of the records of the past trapped in the ice sheet.Abstract. Ice cores provide the most direct evidence available about the past atmosphere. For long-lived trace gases, ice cores have provided clear evidence that in the last two centuries, concentrations of several greenhouse gases have risen well outside the natural range observed in the previous 650 000 years. Major natural changes are also observed between cold and warm periods. Aerosol components have to be interpreted in terms of changing sources, transport and deposition. When this is done, they can also supply evidence about crucial aspects of the past environment, including sea ice extent, trace element deposition to the ocean, and about the aerosols available for cloud nucleation, for example. It is much more difficult to extract information about shorter-lived chemical species. Information may be available in components such as nitrate and formaldehyde, but to extract that information, detailed modern atmospheric studies about air to snow transfer, preservation in the ice, and the link between the polar region boundary layer and other parts of the atmosphere are urgently required.

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“…Inorganic and organic speciation of I and Br has been investigated in many environmental matrices including vertical ocean profiles [9], Atlantic coastal waters [20], water macroalgae [21], open ocean deposition [22], and rain [23], as well as snow deposited at the poles [24] and central Europe [5], but no data are available for iodine and bromine species in polar ice. The polar ice caps are important sites for climate studies due to their ability to archive atmospheric constituents, the possibility for accurate sample dating, and their relative distance from anthropogenic pollution sources.…”

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confidence: 99%

Speciation analysis of iodine and bromine at picogram-per-gram levels in polar ice

Spolaor

Vallelonga²,

Gabrieli

et al. 2012

Anal Bioanal Chem

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Iodine and bromine species participate in key atmospheric reactions including the formation of cloud condensation nuclei and ozone depletion. We present a novel method coupling a high-performance liquid chromatography with ion chromatography and inductively coupled plasma mass spectrometry, which allows the determination of iodine (I) and bromine (Br) species (IO 3 − , I − , Br − , BrO 3 − ) at the picogram-per-gram levels presents in Antarctic ice. Chromatographic separation was achieved using an ION-PAC® AS16 Analytical Column with NaOH as eluent. Detection limits for I and Br species were 5 to 9 pg g −1 with an uncertainty of less than 2.5% for all considered species. Inorganic iodine and bromine species have been determined in Antarctic ice core samples, with concentrations close to the detection limits for iodine species, and approximately 150 pg g −1 for Br − . Although iodate (IO 3 − ) is the most abundant iodine species in the atmosphere, only the much rarer iodide (I − ) species was present in Antarctic Holocene ice. Bromine was found to be present in Antarctic ice as Br − .

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Halogens and their role in polar boundary-layer ozone depletion

Cited by 190 publications

References 268 publications

Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

Past atmospheric composition and chemistry from ice cores - progress and prospects

Speciation analysis of iodine and bromine at picogram-per-gram levels in polar ice

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