Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine
Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine
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DOI：
10.1038/ngeo1687
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发表时间：
2013-02-01
影响因子：
18.3
通讯作者：
Plane, John M. C.
中科院分区：
文献类型：
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作者：
Carpenter, Lucy J.;MacDonald, Samantha M.;Plane, John M. C.
天然存在的含溴和含碘化合物大大降低了区域、甚至可能是全球对流层臭氧水平（1-4）。因此，这些卤素气体降低了对流层中臭氧的全球变暖效应（5），以及其引发诸如甲烷的碳氢化合物的化学去除的能力。大多数与卤素有关的表面臭氧破坏可归因于碘化学（2）。到目前为止，有机碘化合物被认为是海洋碘排放的主要来源（1，6 -9）。然而，已知的大气碘的有机来源不能解释热带海洋上空对流层低层的气相氧化碘浓度（3、4）。在这里，我们量化的气体排放的无机碘与臭氧的反应在一系列的实验室实验。我们表明，碘与臭氧的反应会导致分子碘和次碘酸的形成。使用动力箱模型的海洋表层和一维模型的海洋边界层，我们表明，臭氧与碘化物在海面上的反应可以占约75%的热带大西洋上空观测到的碘氧化物水平。根据海洋表面模型，次碘酸以前不被认为是碘的海洋来源，在环境条件下以比分子碘高十倍的速率排放。
Naturally occurring bromine-and iodine-containing compounds substantially reduce regional, and possibly even global, tropospheric ozone levels(1-4). As such, these halogen gases reduce the global warming effects of ozone in the troposphere(5), and its capacity to initiate the chemical removal of hydrocarbons such as methane. The majority of halogen-related surface ozone destruction is attributable to iodine chemistry(2). So far, organic iodine compounds have been assumed to serve as the main source of oceanic iodine emissions(1,6-9). However, known organic sources of atmospheric iodine cannot account for gas-phase iodine oxide concentrations in the lower troposphere over the tropical oceans(3,4). Here, we quantify gaseous emissions of inorganic iodine following the reaction of iodide with ozone in a series of laboratory experiments. We show that the reaction of iodide with ozone leads to the formation of both molecular iodine and hypoiodous acid. Using a kinetic box model of the sea surface layer and a one-dimensional model of the marine boundary layer, we show that the reaction of ozone with iodide on the sea surface could account for around 75% of observed iodine oxide levels over the tropical Atlantic Ocean. According to the sea surface model, hypoiodous acid-not previously considered as an oceanic source of iodine-is emitted at a rate ten-fold higher than that of molecular iodine under ambient conditions.