Abiotic source of reactive organic halogens in the sub-arctic atmosphere?
Abiotic source of reactive organic halogens in the sub-arctic atmosphere?
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DOI：
10.1021/es050918w
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发表时间：
2005-11-15
影响因子：
11.4
通讯作者：
Constant, P
中科院分区：
文献类型：
--
作者：
Carpenter, LJ;Hopkins, JR;Constant, P
最近的理论研究表明，反应性有机碘碳，如CH 2 I2，将是极有效的代理对流层北极臭氧消耗和碘化合物添加到Br-2/BrCl混合物有一个显着更大的臭氧（和汞）消耗效果比额外的Br-2和BrCl分子。在这里，我们报告的第一个观察CH 2 I2，CH 2 IBr，和CH 2 ICI在北极空气中，以及其他活性卤代烃，包括CHBr 3，在春季在Kuujiuarapik，哈德逊湾。有机碘化合物在空气中的含量是迄今为止报告的最高水平。卤烃的发生与西北风从冻结的海湾，并在CHBr 3的情况下，与臭氧和总气态汞（TGM），这表明无机和有机卤素之间的联系。当地的铅加上极短的大气寿命的CH 2 I2的情况下，表明生产发生在海湾的海冰/覆盖积雪的表面。我们提出了一个非生物机制的生产多卤代碘和溴碳，通过反应的HOI和/或HOBr与有机材料的准液体层以上海冰/积雪，并报告实验室数据来支持这种机制。因此，CH 2 I2、CH 2 IBr和其他有机碘化合物可能是海冰上方空气中普遍存在的成分，它们将增加溴引发的臭氧和汞消耗的效率。
Recent theoretical studies indicate that reactive organic iodocarbons such as CH2I2 would be extremely effective agents for tropospheric Arctic ozone depletion and that iodine compounds added to a Br-2/BrCl mixture have a significantly greater ozone (and mercury) depletion effect than additional Br-2 and BrCl molecules. Here we report the first observations of CH2I2, CH2IBr, and CH2ICI in Arctic air, as well as other reactive halocarbons including CHBr3, during spring at Kuujiuarapik, Hudson Bay. The organoiodine compounds were present at the highest levels yet reported in air. The occurrence of the halocarbons was associated with northwesterly winds from the frozen bay, and, in the case of CHBr3, was anticorrelated with ozone and total gaseous mercury (TGM), suggesting a link between inorganic and organic halogens. The absence of local leads coupled with the extremely short atmospheric lifetime of CH2I2 indicates that production occurred in the surface of the sea-ice/overlying snowpack over the bay. We propose an abiotic mechanism for the production of polyhalogenated iodo- and bromocarbons, via reaction of HOI and/or HOBr with organic material on the quasi-liquid layer above sea-ice/snowpack, and report laboratory data to support this mechanism. CH2I2, CH2IBr, and other organic iodine compounds may therefore be a ubiquitous component of air above sea ice where they will increase the efficiency of bromine-initiated ozone and mercury depletion.