Atmospheric effects of volcanic bromine emissions

Taryn M. Lopez

UAF Department of Chemistry and Biochemistry

Importance of volcanic emissionsImportance of volcanic emissions

Volcano monitoringVolcano monitoringSource of trace gases & Source of trace gases &

aerosols to the aerosols to the atmosphereatmosphere

www.wikipedia.com/

SO2 Emissions from Augustine Volcano

-2000

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www.usgs.govwww.usgs.gov

Doukas and McGee, USGS Open File Report, 2007Doukas and McGee, USGS Open File Report, 2007

Average Composition of an HAverage Composition of an H22O-O-

Rich Magmatic GasRich Magmatic GasAverage Composition of an H2O Rich Magmatic Gas

H2O CO2 SO2 HCl H2S H2 HF CO HBr HI

Gerlach, G Cubed, 2004Gerlach, G Cubed, 2004

BromineBromine

•Halogen elementHalogen element

•Natural reservoirs: saltwater and the earth’s crust Natural reservoirs: saltwater and the earth’s crust http://minerals.usgs.gov/minerals/pubs/commodity/bromine/))

•Abundance in Oceans ~67.3 parts per million Abundance in Oceans ~67.3 parts per million (ppm by weight)(ppm by weight) www.eoearth.org

•Abundance Earth’s crust ~3 ppmAbundance Earth’s crust ~3 ppm (by weight) (by weight)http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth's_crust

•Abundance in Atmosphere ~0.5 – 2 parts per trillion Abundance in Atmosphere ~0.5 – 2 parts per trillion (by volume) (by volume)

(von Glasow et al, Atmos. Chem. Phys. Discuss., 2004)(von Glasow et al, Atmos. Chem. Phys. Discuss., 2004)

www.periodictable.com www.periodictable.com

Annual Global Emissions of HBr (Tg)Annual Global Emissions of HBr (Tg)Annual Global Emissions of HBr (Tg)

Volcanoes

Oceans

Combustion

Cadle, Reviews of Geophysics and Space Physics, 1980Cadle, Reviews of Geophysics and Space Physics, 1980

First detection of volcanic BrOFirst detection of volcanic BrO

• Soufriere Hills volcano, Montserrat, West IndiesSoufriere Hills volcano, Montserrat, West Indies• Bobrowski and others, 2002Bobrowski and others, 2002

www.mvo.ms

Bobrowski et al., Nature, 2003Bobrowski et al., Nature, 2003

Scanning Multiaxis (MAX) DOASScanning Multiaxis (MAX) DOAS

•Entrance optics (0.6 deg FOV)Entrance optics (0.6 deg FOV)

•Quartz optical fibersQuartz optical fibers

•Ocean Optics USB 2000 UV/Vis Ocean Optics USB 2000 UV/Vis spectrometerspectrometer

•Internal stepper motorInternal stepper motor

•Temperature stabilized to 10 deg CTemperature stabilized to 10 deg C

Bobrowski et al, JGR, 2007Bobrowski et al, JGR, 2007

Ocean Optics SpectrometerOcean Optics Spectrometer

www.oceanoptics.com

Ocean Optics SpectrometerOcean Optics Spectrometer

www.oceanoptics.com

Ocean Optics SpectrometerOcean Optics Spectrometer

www.oceanoptics.com

Beer-Lambert LawBeer-Lambert Law

Io = Incident light Io = Incident light εε = Molar absorptivity = Molar absorptivity c = Concentrationc = Concentrationl = Path lengthl = Path length

-ln(I/Io) = σNL (Physics)

A = -log10 (I/Io) = εcl (Chemistry)

I = Transmitted lightI = Transmitted lightσσ = Absorption x-section = Absorption x-section N = Concentration N = Concentration L = Path lengthL = Path length

Application of Beer’s Law

MAX DOAS

Reference Spectrum

Sample Spectrum

MAX DOAS

Reference Spectrum

Reference Spectrum

Sample Spectrum

Wahner et al., Chem. Phys. Letters, 1988; Weibring, Diploma Thesis, 1986Wahner et al., Chem. Phys. Letters, 1988; Weibring, Diploma Thesis, 1986

BrO and SO2 Absorption Spectra

0.00E+00

2.00E-18

4.00E-18

6.00E-18

8.00E-18

1.00E-17

1.20E-17

1.40E-17

1.60E-17

1.80E-17

280 300 320 340 360

Wavelength (nm)

cm

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0.00E+00

1.00E-19

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BrO SO2

MAX DOAS

From Bobrowski et al., Nature, 2003

MAX-DOAS methodology

Volcanoes: A significant source of Volcanoes: A significant source of atmospheric BrO!atmospheric BrO!

• BrO slant column density (SCD) of 2 x 10BrO slant column density (SCD) of 2 x 1015 15 molecules/cmmolecules/cm22

• Derived mixing ratio ~ 1 ppbv BrODerived mixing ratio ~ 1 ppbv BrO• Estimated emission rate 8.4 x 10Estimated emission rate 8.4 x 1022 22 molecules/s molecules/s

or ~350 t reactive Br/yearor ~350 t reactive Br/year• Global estimate of Br from volcanoesGlobal estimate of Br from volcanoes

14 +/- 6 Tg/year ~ 30,000 t Br/year14 +/- 6 Tg/year ~ 30,000 t Br/year

*Using these estimates and total global Br source flux to *Using these estimates and total global Br source flux to the atmosphere of ~60 – 120 molec/cmthe atmosphere of ~60 – 120 molec/cm33/s /s (von Glasow, (von Glasow,

2004);2004); volcanic bromine makes up ~ 0.8 – 1.6% of total! volcanic bromine makes up ~ 0.8 – 1.6% of total!

(1 molec/cm(1 molec/cm33/s)/s)Bobrowski et al., Nature, 2003Bobrowski et al., Nature, 2003

BrO•

Source?

Effects?

BrO•

Source?

Effects?

Redox Chemistry!

BrO•

Source?

Effects?

Redox Chemistry!

Ozone depletion!

BrO formation in volcanic plumesBrO formation in volcanic plumes

• Case studies: Mt. Etna volcano, Italy Case studies: Mt. Etna volcano, Italy Oppenheimer et al., Geochimica Acta, 2006 & Oppenheimer et al., Geochimica Acta, 2006 &

Bobrowski et al., JGR, 2007Bobrowski et al., JGR, 2007

• Collected BrO and SOCollected BrO and SO2 2 SCD measurements SCD measurements

at 0 km and downwind from sourceat 0 km and downwind from source

Oppenheimer et al., Geochimica Acta, 2006Oppenheimer et al., Geochimica Acta, 2006Image Science and Analysis Laboratory, NASA-Johnson Space Center

BrO concentrations increase with timeBrO concentrations increase with time

• Observed an increase in BrO/SOObserved an increase in BrO/SO22

downwind from plume sourcedownwind from plume source– BrO values below detection limit near ventBrO values below detection limit near vent

– BrO/SOBrO/SO22 ~ 4.5 x 10 ~ 4.5 x 10-4-4 at 19 km downwind at 19 km downwind

• Noticed higher BrO/SONoticed higher BrO/SO22 at the edges of at the edges of

plumeplume

Bobrowski et al., GRL, 2007Bobrowski et al., GRL, 2007

BrO concentrations increase with timeBrO concentrations increase with time

Oppenheimer et al., Geochimica Acta, 2006Oppenheimer et al., Geochimica Acta, 2006

Where does the BrO come from?Where does the BrO come from?

• HBr found in fluid inclusions in volcanic HBr found in fluid inclusions in volcanic rocks and in gas condensates rocks and in gas condensates (Bureau et al., EPSL, 2000; Gerlach et al., G Cubed, 2004)(Bureau et al., EPSL, 2000; Gerlach et al., G Cubed, 2004)

• HBr is the thermodynamically stable Br HBr is the thermodynamically stable Br species in magma and the atmospherespecies in magma and the atmosphere(Oppenheimer et al., Geochimica Acta, 2006)(Oppenheimer et al., Geochimica Acta, 2006)

Conversion of HBr to BrOConversion of HBr to BrO

Gas Phase RXN:Gas Phase RXN:

(1)(1) HBrHBrgg + + ∙∙OHOHgg → Br∙→ Br∙gg + H + H22OOgg

k = 1.1 x 10k = 1.1 x 10-11-11 cm cm33/molecule*s/molecule*s

(2)(2) Br∙Br∙gg + O + O3g3g BrO∙ BrO∙gg + O + O2 g2 g

• The value of k, combined with low [OH] The value of k, combined with low [OH] makes this sequence too slow to explain makes this sequence too slow to explain BrO observations.BrO observations.

Finlayson Pitts and Pitts, Chemistry of the Upper and Lower Atmosphere, 2000Finlayson Pitts and Pitts, Chemistry of the Upper and Lower Atmosphere, 2000

Conversion of HBr to BrO: Conversion of HBr to BrO: Heterogeneous reactionsHeterogeneous reactions

(3)(3) BrO∙g∙g +HO2∙∙gg HOBr HOBrgg + O + O2g2g

(4)(4) HOBrHOBrgg HOBr HOBraqaq

(5)(5) HOBrHOBraqaq + HBr + HBraqaq Br Br2aq2aq +H +H22OOaqaq

(6)(6) BrBr2aq2aq Br Br2g2g

(7)(7) BrBr2g2g+ hv + hv 2Br 2Br∙g∙g

(8)(8) BrBr∙g∙g + O + O3g3g BrO BrO∙g∙g + O + O2g2g

(9)(9) Net: HONet: HO22∙g∙g+O+O3g3g+hv+HBr+hv+HBrggHH22OOaq+aq+2O2O2g2g+Br+Br∙g∙g

Reaction requires a surface (sulfate aerosols)!Reaction requires a surface (sulfate aerosols)!

5 m/s plume speed

3340 m3340 m

30 m

30 m

Can field observations be replicated using a Can field observations be replicated using a chemical model?chemical model?

Bobrowski et al., GRL, 2007

•1D model “MISTRA” (von 1D model “MISTRA” (von Glasow, 2002)Glasow, 2002)

•Air parcel moves across Air parcel moves across volcanovolcano

•Gas and aerosol chemistry Gas and aerosol chemistry (170 gas phase & 265 aqueous (170 gas phase & 265 aqueous phase rxns)phase rxns)

•Vertical and horizontal dilutionVertical and horizontal dilution

Model input parametersModel input parameters

• Initial plume: 78% HInitial plume: 78% H22O, 8.7% COO, 8.7% CO22, 2.6% SO, 2.6% SO22, ,

1.3% HCl, 0.006% HBr 1.3% HCl, 0.006% HBr

• Volcanic gas + atmospheric air mixture at Volcanic gas + atmospheric air mixture at thermodynamic equilibriumthermodynamic equilibrium

• Temperature 600 deg CTemperature 600 deg C

• Equilibrium composition calculated at 10 s time Equilibrium composition calculated at 10 s time intervalsintervals

Bobrowski et al., GRL, 2007Bobrowski et al., GRL, 2007

BrO forms in volcanic plumeBrO forms in volcanic plume

Bobrowski et al., GRL, 2007Bobrowski et al., GRL, 2007

SOSO22: Plume diffusion tracer: Plume diffusion tracer

Bobrowski et al., GRL, 2007Bobrowski et al., GRL, 2007

•SOSO22 concentration in plume decreases gradually as plume concentration in plume decreases gradually as plume

diffuses with timediffuses with time

•BrO/SOBrO/SO22 plot reflects that BrO is affected by chemical plot reflects that BrO is affected by chemical

reactions in addition to plume diffusionreactions in addition to plume diffusion

BrO∙ Effects?

HBr

Bromine activation (HBr Br BrO)

Br Ozone Destruction CycleBr Ozone Destruction Cycle

BrOBrO••

HOBrHOBr

Br •Br •

HOHO22••

OO22hvhv

•• OHOH

OO33 OO22

Net RXN: ONet RXN: O33 + HO + HO22 + hv + hv 2O 2O22 + OH + OH

von Glasow et al., Atmos. Chem. Phys. Discuss., 2004von Glasow et al., Atmos. Chem. Phys. Discuss., 2004

Br and HOx Catalytic Cycle Br and HOx Catalytic Cycle

BrOBrO••

HOBrHOBr

Br •Br •

HOHO22••

OO22hvhv

•• OHOH

OO33 OO22

CO + OCO + O22 COCO22

Net RXN: CO + ONet RXN: CO + O33 CO CO22 + 2O + 2O22

von Glasow et al., Atmos. Chem. Phys. Discuss., 2004von Glasow et al., Atmos. Chem. Phys. Discuss., 2004

Model shows inverse relationship Model shows inverse relationship between Ozone and BrObetween Ozone and BrO

Bobrowski et al., GRL, 2007Bobrowski et al., GRL, 2007

• 20 minutes following model initiation, O20 minutes following model initiation, O33 levels drop to levels drop to

near zeronear zero

• At this time BrO levels begin to sharply increaseAt this time BrO levels begin to sharply increase

• After 90 minutes OAfter 90 minutes O33 levels begin to increase as plume levels begin to increase as plume

mixes with ambient airmixes with ambient air

Use chemical transport model Use chemical transport model MATCH-MPIC to test theoryMATCH-MPIC to test theory

• 3D chemical transport model (MATCH-MPIC) to 3D chemical transport model (MATCH-MPIC) to test impacts of BrO on Otest impacts of BrO on O33 in the troposphere in the troposphere

• Included comprehensive gas phase chemistry and Included comprehensive gas phase chemistry and HBr heterogeneous rxnsHBr heterogeneous rxns

• Global Br source of 60 - 120 molec*cmGlobal Br source of 60 - 120 molec*cm-3-3*s*s-1-1

• 4 scenarios different latitude and compositions4 scenarios different latitude and compositionsvonvon Glasow et al., Atmos. Chem. Phys. Discuss., 2004Glasow et al., Atmos. Chem. Phys. Discuss., 2004

BrO depletes OBrO depletes O33

according to model resultsaccording to model results

• BrO mixing ratios of < 2 pptv can result in:BrO mixing ratios of < 2 pptv can result in:

– 18% reduction in mean tropospheric O18% reduction in mean tropospheric O33

mixing ratios (large areas)mixing ratios (large areas)

– 40% reduction in mean tropospheric O40% reduction in mean tropospheric O33

mixing ratios (localized areas)mixing ratios (localized areas)

vonvon Glasow et al., Atmos. Chem. Phys. Discuss., 2004Glasow et al., Atmos. Chem. Phys. Discuss., 2004

Do reactive halogens cause localized ozone Do reactive halogens cause localized ozone holes near volcanoes?holes near volcanoes?

Case study: Sakurajima VolcanoCase study: Sakurajima Volcano

• BrO, ClO, and SOBrO, ClO, and SO22 SCD were SCD were

measured downwind of measured downwind of Sakurajima volcanoSakurajima volcano

• Direct SODirect SO22 and O and O33 also also

measured at Observatorymeasured at Observatory

• Strong correlation between Strong correlation between BrO, ClO, and SOBrO, ClO, and SO22 species species

Lee et al., GRL, 2005Lee et al., GRL, 2005

http://landsat.usgs.gov/gallery/ http://landsat.usgs.gov/gallery/

Increase in SOIncrease in SO22 corresponds corresponds

with decrease in Owith decrease in O33

Lee et al., GRL, 2005Lee et al., GRL, 2005

HBr

Bromine activation (HBr Br BrO) BrO•

Ozone depletion (O3 + HO2 + hv 2O2 +

OH)

Do large volcanic eruptions cause Do large volcanic eruptions cause global stratospheric ozone global stratospheric ozone

depletion due to Br chemistry?depletion due to Br chemistry?

Kasatochi Volcanic EruptionKasatochi Volcanic Eruption August 2008August 2008

– Injected 1.5 Mt SOInjected 1.5 Mt SO22 into atmosphere into atmosphere (Pinatubo (Pinatubo 20 Mt) 20 Mt)

– Plume to 40,000 feet elevation Plume to 40,000 feet elevation (stratosphere for Kasatochi’s latitude)(stratosphere for Kasatochi’s latitude)

– SOSO22 cloud circled globe in 21 days cloud circled globe in 21 days

– Using BrO/SOUsing BrO/SO22 ratio of ~ 10 ratio of ~ 10-4-4 (Bobrowski et al., 2007) (Bobrowski et al., 2007) 150 t BrO injected into atmosphere 150 t BrO injected into atmosphere

Alaska Volcano Observatory, Internal Logs, August 2008; Photo by Chris WaythomasAlaska Volcano Observatory, Internal Logs, August 2008; Photo by Chris Waythomas

Kasatochi SOKasatochi SO2 2 Cloud Cloud Circles GlobeCircles Globe

Image by Simon Carn, NASA JCETImage by Simon Carn, NASA JCET

ConclusionsConclusions• Volcanic bromine emissions account for a Volcanic bromine emissions account for a

significant amount of total atmospheric Brsignificant amount of total atmospheric Br• Volcanically emitted HBr can produce BrOVolcanically emitted HBr can produce BrO

via heterogeneous reactions on sulfate aerosolsvia heterogeneous reactions on sulfate aerosols

• BrO can catalytically react in an OBrO can catalytically react in an O33 destruction destruction

cyclecycle• BrO in volcanic plumes may cause localized BrO in volcanic plumes may cause localized

ozone holesozone holes

Future WorkFuture Work

Could large volcanic eruptions significantly deplete Could large volcanic eruptions significantly deplete stratospheric ozone due to BrO chemistry? stratospheric ozone due to BrO chemistry?

Thank you for your attention!

Questions?