Ozone depletion: BrOx-HOx-NOx chemistry

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Ozone depletion BrOx-HOx-NOx chemistry

• Dian Putrasahan

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Objective

1. Introduction
2. BrOx chemistry
3. HOx-NOx chemistry
4. Modelling input
5. Results
6. Summary

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Introduction

• Near total ozone depletion events are due to both
  physical and chemical mechanism
• Chemical mechanism include fast catalytic loss
  driven by bromine oxide radicals (BrOx Br
  BrO)
• Presence of aerosols allows heterogeneous
  reactions that further enhances ozone depletion.

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BrOx and O3

• Catalytic mechanism for O3 depletion
• 2 x (Br O3 ? BrO O2)
• BrO BrO ? Br2 O2
• Br2 h? ? 2Br
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• Net 2 O3 ? 3 O2
• Aerosol effect
• Br- HOBr H ? Br2 H2O
• Br2 h? ? 2Br

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BrOx Chemistry
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HOxNOx chemistry
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Modeling of BrOx-NOx-HOx Chemistry

• Facsimile Program
• Input of 37 reactions (8 aqueous reactions, 5
  vapor-liquid equilibrium reactions, 24 gas phase
  reactions)
• Set condition O3 (5ppbv), Br- (23pptv), BrO
  (10pptv), NO (2.9pptv), NO2 (2.4pptv) pH (0.5)

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BrO and Br effect
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BrO Effect
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Ozone effect on Br
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Ozone effect on Br-
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Effects of NOx
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Ozone effect on NOx
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Summary

• Increase in BrO and/or Br will increase the rate
  of ozone depletion
• Br reaches steady state faster as O3
  concentration decreases
• Br- reaches depletes faster as O3 concentration
  increases
• Increase in NOx concentrations can prevent total
  ozone depletion
• NOx acquires steady state faster as O3
  concentration decreases

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