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Title: Potential influence of iodine-containing compounds on the chemistry of the troposphere in the polar spring. I. Ozone depletion

Potential influence of iodine-containing compounds on the chemistry of the troposphere in the polar spring. I. Ozone depletion Iodine in the atmosphere, identified largely by the presence of IO, is a ubiquitous component of the troposphere in coastal and oceanic areas. The role, if any, that iodine chemistry plays in the polar ozone depletion episodes is not known. These events are rationalized today largely in terms of Br2- and BrCl-initiated reactions. The potential for enhancement of ozone depletions through the presence of iodine-containing molecules (I{sub 2}, IBr, ICl, CH{sub 2}I{sub 2}, CH{sub 2}IBr, CH{sub 2}ICl, and CH{sub 3}I) is investigated in this study. Computer simulations of the homogeneous chemistry are made using a reasonably complete reaction mechanism for Br-, Cl- and I-containing species together with representative chemistry of trace gases in the clean troposphere. The extent of uncertain alternative pathways and efficiencies for OIO and I{sub 2}O{sub 2} photolyses are varied over a range of possible values to establish the sensitivity of the depletion events to these variables. The study shows that significant enhancements of the polar ozone depletion are expected when small amounts of iodine-containing compounds such as CH{sub 2}I{sub 2}, IBr, or ICl are present in a polar air mass containing representative Br{sub 2}-BrCl-trace gas mixtures. The synergistic effect of the iodine compounds results from additional more » halogen-atom formation from IO-IO, IO-BrO, and IO-ClO reactions. Measurements of IO and precursor iodine-containing compounds are encouraged for future polar spring studies, as well as currently acknowledged important trace species (O{sub 3}, CH{sub 2}O, BrO, Br{sub 2}, and BrCl). « less
Authors: ;
Publication Date:
OSTI Identifier:OSTI ID: 967084
DOE Contract Number:DE-AC05-00OR22725
Resource Type:Journal Article
Resource Relation:Journal Name: Atmospheric Environment; Journal Volume: 38; Journal Issue: 30
Research Org:Oak Ridge National Laboratory (ORNL)
Sponsoring Org:ORNL work for others
Country of Publication:United States
Language:English
Subject: 54 ENVIRONMENTAL SCIENCES; ATMOSPHERIC CHEMISTRY; COMPUTERIZED SIMULATION; IODINE; IODINE COMPOUNDS; OZONE LAYER; TROPOSPHERE; BROMINE COMPOUNDS; CHLORINE COMPOUNDS; POLAR REGIONS Artic O3 depletion; Computer simulations; Atmospheric chemistry; Iodine-containing compounds