Ozone depletion: Ozone depletion: BrOBrOxx-HO-HOxx-NO-NOxx chemistry chemistry

Dian PutrasahanDian Putrasahan

ObjectiveObjective

1.1. IntroductionIntroduction

2.2. BrOBrOxx chemistry chemistry

3.3. HOHOxx-NO-NOxx chemistry chemistry

4.4. Modelling inputModelling input

5.5. ResultsResults

6.6. SummarySummary

IntroductionIntroduction

• Near total ozone depletion events are Near total ozone depletion events are due to both physical and chemical due to both physical and chemical mechanismmechanism

• Chemical mechanism include fast Chemical mechanism include fast catalytic loss driven by bromine oxide catalytic loss driven by bromine oxide radicals (BrOradicals (BrOxx = Br + BrO) = Br + BrO)

• Presence of aerosols allows Presence of aerosols allows heterogeneous reactions that further heterogeneous reactions that further enhances ozone depletion.enhances ozone depletion.

BrOBrOxx and O and O33

Catalytic mechanism for OCatalytic mechanism for O33 depletion: depletion:

2 x 2 x ((BrBr + O + O33 → BrO + O→ BrO + O22))

BrO + BrO → BrBrO + BrO → Br22 + O + O22

BrBr22 + h + hνν → 2Br → 2Br________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Net:Net: 2 O2 O33 → 3 O → 3 O22

Aerosol effect:Aerosol effect:

BrBr-- + HOBr + H + HOBr + H++ → Br → Br22 + H + H22OO

BrBr22 + h + hνν → 2Br → 2Br

BrOBrOxx Chemistry Chemistry

HOHOxx–NO–NOxx chemistry chemistry

Modeling of BrOModeling of BrOxx-NO-NOxx-HO-HOxx ChemistryChemistry

• Facsimile ProgramFacsimile Program

• Input of 37 reactions (8 aqueous Input of 37 reactions (8 aqueous reactions, 5 vapor-liquid equilibrium reactions, 5 vapor-liquid equilibrium reactions, 24 gas phase reactions)reactions, 24 gas phase reactions)

• Set condition: OSet condition: O33 (5ppbv), Br (5ppbv), Br-- (23pptv), BrO (10pptv), NO (2.9pptv), (23pptv), BrO (10pptv), NO (2.9pptv), NONO22 (2.4pptv) pH (0.5) (2.4pptv) pH (0.5)

BrO and Br effectBrO and Br effectBrO Br effect

6.00E+08

8.00E+08

1.00E+09

1.20E+09

1.40E+09

1.60E+09

1.80E+09

2.00E+09

205000 215000 225000 235000 245000 255000 265000 275000 285000 295000

Time (seconds)

O3

conc

(mol

ecul

es/c

m3)

BrO (1e7mcl/cc) Br (0.3e6mcl/cc)l

BrO (2.5e7mcl/cc) Br (1.3e6mcl/cc)

BrO (4e7mcl/cc) Br (1.8e6mcl/cc)

BrO EffectBrO EffectBrO effect

0.00E+00

2.00E+10

4.00E+10

6.00E+10

8.00E+10

1.00E+11

1.20E+11

1.40E+11

0 50000 100000 150000 200000 250000 300000

Time (seconds)

O3

conc

. (m

olec

ules

/cm

3)

BrO 10pptv BrO 0.1pptv BrO 5pptv BrO 25pptv BrO 50pptv

Ozone effect on BrOzone effect on BrEffect of ozone on Br

0

50000000

100000000

150000000

200000000

250000000

300000000

0 50000 100000 150000 200000 250000 300000

Time (seconds)

Br c

once

ntra

tion

O3 5ppbv O3 1ppbv O3 3 ppbv O3 7ppbv O3 10ppbv

Ozone effect on Br-Ozone effect on Br-Ozone effect on Br-

-0.05

0

0.05

0.1

0.15

0.2

0.25

0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000

Time (seconds)

Br-

(mol

es/L

)

O3 1ppbv O3 5ppbv O3 3ppbv O3 7ppbv O3 10ppbv

Effects of NOEffects of NOxx

NOx effect on ozone depletion

0.00E+00

2.00E+10

4.00E+10

6.00E+10

8.00E+10

1.00E+11

1.20E+11

1.40E+11

0 50000 100000 150000 200000 250000 300000

Time (seconds)

O3

conc

entr

atio

n (m

olec

ules

/cm

3)

NO (2.9pptv), NO2 (2.4 pptv) NO and NO2 (0pptv)

NO (6.1pptv), NO2 (4.8pptv) NO (15.9pptv), NO2 (5.3pptv)

Ozone effect on NOOzone effect on NOxx

O3 effect on NOx

0

20000000

40000000

60000000

80000000

100000000

120000000

140000000

0 50000 100000 150000 200000 250000 300000

Time (seconds)

NO

x co

ncen

trat

ion

(mol

ecul

es/c

m3)

NO (O3 1ppbv) NO2 (O3 1ppbv)NO(O3 5ppbv) NO2 (O3 5ppbv)NO (O3 10ppbv) NO2 (O3 10ppbv)

SummarySummary• Increase in BrO and/or Br will increase the Increase in BrO and/or Br will increase the

rate of ozone depletionrate of ozone depletion• Br reaches steady state faster as OBr reaches steady state faster as O33

concentration decreasesconcentration decreases• BrBr-- reaches depletes faster as O reaches depletes faster as O33

concentration increasesconcentration increases• Increase in NOIncrease in NOxx concentrations can concentrations can

prevent total ozone depletionprevent total ozone depletion• NONOxx acquires steady state faster as O acquires steady state faster as O33

concentration decreasesconcentration decreases