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Ozone depletion: BrO x -HO x -NO x chemistry. Dian Putrasahan. Objective. Introduction BrO x chemistry HO x -NO x chemistry Modelling input Results Summary. Introduction. Near total ozone depletion events are due to both physical and chemical mechanism - PowerPoint PPT Presentation
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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