Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

Wachsmuth, Malte; Gäggeler, H. W.; Glasow, R. von; Ammann, Markus

doi:10.5194/acp-2-121-2002

Cited by 41 publications

(24 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Diurnal patterns of BrO with maxima in the daytime have been observed [e.g., Hausmann and Platt, 1994;Saiz-Lopez et al, 2007;Pöhler et al, 2010;Liao et al, 2011a], which confirmed that BrO is a photochemically generated species with a short lifetime [e.g., Evans et al, 2003;Fan and Jacob, 1992]. BrO is the dominant bromine radical when O 3 is not severely depleted (O 3 > 1 ppbv), and observations of this species are crucial for understanding the chemical processing that leads to ODEs [e.g., Sander et al, 1997;von Glasow et al, 2002;Jones et al, 2009;Yang et al, 2010].…”

Section: Introductionmentioning

confidence: 83%

See 1 more Smart Citation

Observations of inorganic bromine (HOBr, BrO, and Br₂) speciation at Barrow, Alaska, in spring 2009

Liao¹,

Huey²,

Tanner³

et al. 2012

J. Geophys. Res.

123

View full text Add to dashboard Cite

[1] Inorganic bromine plays a critical role in ozone and mercury depletions events (ODEs and MDEs) in the Arctic marine boundary layer. Direct observations of bromine species other than bromine oxide (BrO) during ODEs are very limited. Here we report the first direct measurements of hypobromous acid (HOBr) as well as observations of BrO and molecular bromine (Br 2 ) by chemical ionization mass spectrometry at Barrow, Alaska in spring 2009 during the Ocean-Atmospheric-Sea Ice-Snowpack (OASIS) campaign. Diurnal profiles of HOBr with maximum concentrations near local noon and no significant concentrations at night were observed. The measured average daytime HOBr mixing ratio was 10 pptv with a maximum value of 26 pptv. The observed HOBr was reasonably well correlated (R 2 = 0.57) with predictions from a simple steady state photochemical model constrained to observed BrO and HO 2 at wind speeds <6 m s À1 . However, predicted HOBr levels were considerably higher than observations at higher wind speeds. This may be due to enhanced heterogeneous loss of HOBr on blowing snow coincident with higher wind speeds. BrO levels were also found to be higher at elevated wind speeds. Br 2 was observed in significant mixing ratios (maximum = 46 pptv; average = 13 pptv) at night and was strongly anti-correlated with ozone. The diurnal speciation of observed gas phase inorganic bromine species can be predicted by a time-dependent box model that includes efficient heterogeneous recycling of HOBr, hydrogen bromide (HBr), and bromine nitrate (BrONO 2 ) back to more reactive forms of bromine.

show abstract

Section: Introductionmentioning

confidence: 83%

“…[17] The mass accommodation coefficient of HOBr on aerosol particles in the calculation of k a is estimated to be 0.6 [Wachsmuth et al, 2002]. The rate coefficient for reaction (R3), k 3 , is taken from a kinetics database [Sander et al, 2006].…”

Section: Steady State Calculation Of Hobrmentioning

confidence: 99%

Observations of inorganic bromine (HOBr, BrO, and Br₂) speciation at Barrow, Alaska, in spring 2009

Liao¹,

Huey²,

Tanner³

et al. 2012

J. Geophys. Res.

123

View full text Add to dashboard Cite

show abstract

“…Abbatt (1995) measured γ > 0.25 for HBr + HOBr in sulfuric acid solution (69 wt %) with HBr present in excess. Laboratory measurements show that HOBr reactive uptake on deliquescent NaBr and NaCl aerosol has γ > 0.2 for pH < 7 (Abbatt and Waschewsky, 1998;Fickert et al, 1999;Wachsmuth et al, 2002). Fickert et al (1999) determined the relative production of Br 2 vs. BrCl for HOBr reacting with aqueous salt solutions containing both Br − and Cl − , and found ≥ 90 % Br 2(g) production for [Br − ]/[Cl − ] ratios typical of seawater.…”

Section: Chemical Cycling Of Br Ymentioning

confidence: 99%

Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

et al. 2012

View full text Add to dashboard Cite

Abstract. We present a new model for the global tropospheric chemistry of inorganic bromine (Br y ) coupled to oxidant-aerosol chemistry in the GEOS-Chem chemical transport model (CTM). Sources of tropospheric Br y include debromination of sea-salt aerosol, photolysis and oxidation of short-lived bromocarbons, and transport from the stratosphere. Comparison to a GOME-2 satellite climatology of tropospheric BrO columns shows that the model can reproduce the observed increase of BrO with latitude, the northern mid-latitudes maximum in winter, and the Arctic maximum in spring. This successful simulation is contingent on the HOBr + HBr reaction taking place in aqueous aerosols and ice clouds. Bromine chemistry in the model decreases tropospheric ozone mixing ratios by < 1-8 nmol mol −1 (6.5 % globally), with the largest effects in the northern extratropics in spring. The global mean tropospheric OH concentration decreases by 4 %. Inclusion of bromine chemistry improves the ability of global models (GEOS-Chem and p-TOMCAT) to simulate observed 19th-century ozone and its seasonality. Bromine effects on tropospheric ozone are comparable in the present-day and pre-industrial atmospheres so that estimates of anthropogenic radiative forcing are minimally affected. Br atom concentrations are 40 % higher in the pre-industrial atmosphere due to lower ozone, which would decrease by a factor of 2 the atmospheric lifetime of elemental mercury against oxidation by Br. This suggests that historical anthropogenic mercury emissions may have mostly deposited to northern mid-latitudes, enriching the corresponding surface reservoirs. The persistent rise in background surface ozone at northern mid-latitudes during the past decades could possibly contribute to the observations of elevated mercury in subsurface waters of the North Atlantic.

show abstract

“…Subsequent laboratory studies have demonstrated that Reaction (R3) is efficient on saline liquid, ice, and aerosol particle surfaces (Fickert et al, 1999;Huff andAbbatt, 2000, 2002;Wachsmuth et al, 2002;Abbatt et al, 2012;Wren et al, 2013;Roberts et al, 2014). Other mechanisms of halogen activation also exist, such as the reaction of ozone with aerosol or ice-bound bromide (Oum et al, 1998;Hunt et al, 2004), but these processes are typically slower than photochemical bromine release.…”

Section: Snowpack-based Bro Events Were Common During Bromexmentioning

confidence: 99%

“…In the absence of diffusion limitations (e.g., typically for submicron particles), the rate of a heterogeneous reaction is k het = 1/4cγ SA, where c is the average velocity of the gas, and γ is the reaction probability. Wachsmuth et al (2002) indicate that heterogeneous uptake of HOBr on sea salt aerosol particles is limited by accommodation and has the value γ = 0.6. The actual value of γ may be lower because ambient particles are likely not solely sea salt.…”

Section: Aerosol Extinction Aloft Was Necessary But Not Sufficient Fomentioning

confidence: 99%

Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS

et al. 2017

View full text Add to dashboard Cite

Abstract. Heterogeneous photochemistry converts bromide (Br − ) to reactive bromine species (Br atoms and bromine monoxide, BrO) that dominate Arctic springtime chemistry. This phenomenon has many impacts such as boundarylayer ozone depletion, mercury oxidation and deposition, and modification of the fate of hydrocarbon species. To study environmental controls on reactive bromine events, the BRomine, Ozone, and Mercury EXperiment (BROMEX) was carried out from early March to mid-April 2012 near Barrow (Utqiaġvik), Alaska. We measured horizontal and vertical gradients in BrO with multiple-axis differential optical absorption spectroscopy (MAX-DOAS) instrumentation at three sites, two mobile and one fixed. During the campaign, a large crack in the sea ice (an open lead) formed pushing one instrument package ∼ 250 km downwind from Barrow (Utqiaġvik). Convection associated with the open lead converted the BrO vertical structure from a surfacebased event to a lofted event downwind of the lead influence. The column abundance of BrO downwind of the refreezing lead was comparable to upwind amounts, indicating direct reactions on frost flowers or open seawater was not a major reactive bromine source. When these three sites were separated by ∼ 30 km length scales of unbroken sea ice, the BrO amount and vertical distributions were highly correlated for most of the time, indicating the horizontal length scales of BrO events were typically larger than ∼ 30 km in the absence of sea ice features. Although BrO amount and vertical distribution were similar between sites most of the time, rapid changes in BrO with edges significantly smaller than this ∼ 30 km length scale episodically transported between the sites, indicating BrO events were large but with sharp edge contrasts. BrO was often found in shallow layers that recycled reactive bromine via heterogeneous reactions on snowpack. Episodically, these surface-based events propagated aloft when aerosol extinction was higher (> 0.1 km −1 ); however, the presence of aerosol particles aloft was not sufficient to produce BrO aloft. Highly depleted ozone (< 1 nmol mol −1 ) repartitioned reactive bromine away from BrO and drove BrO events aloft in cases. This work demonstrates the interplay between atmospheric mixing and heterogeneous chemistry that affects the vertical structure and horizontal extent of reactive bromine events.

show abstract

Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

Cited by 41 publications

References 72 publications

Observations of inorganic bromine (HOBr, BrO, and Br₂) speciation at Barrow, Alaska, in spring 2009

Observations of inorganic bromine (HOBr, BrO, and Br₂) speciation at Barrow, Alaska, in spring 2009

Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS

Contact Info

Product

Resources

About

Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

Cited by 41 publications

References 72 publications

Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009

Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009

Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS

Contact Info

Product

Resources

About

Observations of inorganic bromine (HOBr, BrO, and Br₂) speciation at Barrow, Alaska, in spring 2009

Observations of inorganic bromine (HOBr, BrO, and Br₂) speciation at Barrow, Alaska, in spring 2009