Abiotic Source of Reactive Organic Halogens in the Sub-Arctic Atmosphere?

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• 作者：Lucy J. Carpenter ; James R. Hopkins ; Charlotte E. Jones ; Alastair C. Lewis ; Rajendran Parthipan ; David J. Wevill ; Laurier Poissant ; Martin Pilote ; and Philippe Constant
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：November 15, 2005
• 年：2005
• 卷：39
• 期：22
• 页码：8812 - 8816
• 全文大小：424K
• 年卷期：v.39,no.22(November 15, 2005)
• ISSN：1520-5851

文摘

Recent theoretical studies indicate that reactive organiciodocarbons such as CH₂I₂ would be extremely effectiveagents for tropospheric Arctic ozone depletion and thatiodine compounds added to a Br₂/BrCl mixture have asignificantly greater ozone (and mercury) depletion effectthan additional Br₂ and BrCl molecules. Here we reportthe first observations of CH₂I₂, CH₂IBr, and CH₂ICl in Arcticair, as well as other reactive halocarbons includingCHBr₃, during spring at Kuujjuarapik, Hudson Bay. Theorganoiodine compounds were present at the highest levelsyet reported in air. The occurrence of the halocarbonswas associated with northwesterly winds from the frozenbay, and, in the case of CHBr₃, was anticorrelated withozone and total gaseous mercury (TGM), suggesting a linkbetween inorganic and organic halogens. The absenceof local leads coupled with the extremely short atmosphericlifetime of CH₂I₂ indicates that production occurred inthe surface of the sea-ice/overlying snowpack over thebay. We propose an abiotic mechanism for the productionof polyhalogenated iodo- and bromocarbons, via reactionof HOI and/or HOBr with organic material on the quasi-liquid layer above sea-ice/snowpack, and report laboratorydata to support this mechanism. CH₂I₂, CH₂IBr, and otherorganic iodine compounds may therefore be a ubiquitouscomponent of air above sea ice where they will increasethe efficiency of bromine-initiated ozone and mercurydepletion.