The production of ozone-depleting bromocarbon gases in near-shore Antarctic waters

在海面和大气之间存在着持续的双向化学物质交换。溴碳是一组在海水中自然产生的挥发性化合物，将元素溴从海洋水库带入大气。一旦进入大气层，溴就会对那里发生的化学作用产生重要影响。这种通量的主要影响是空气中臭氧的数量减少，这可以减少有害温室气体分解的可能性，并导致到达地球表面的有害紫外线的数量增加。了解这些溴碳化合物是如何、何时、在哪里在海洋环境中产生的，对于我们能够预测它们对地球系统的影响至关重要。我们最近在南极的研究结果表明，溴碳化合物溴甲烷(CHBr3)和二溴甲烷(CH2Br2)是在浮游植物水华期间产生的，浮游植物在夏季(10月至5月)海冰破裂时发生。像我们研究的那样的水华发生在夏季被称为西南极半岛的整个南极地区。如果在所有这些水华中都有溴碳的产生，那么在南极夏季可能会有大量的溴从海到空气的通量，这可能会对大气化学产生重要影响。在这项研究中，我们建议确定影响海冰边缘浮游植物水华中溴碳浓度的主要生物、化学和物理过程，并利用这一知识通过数学模型估计海-空气溴通量的潜在影响。

There is a continual two-way exchange of chemicals between the sea-surface and the atmosphere. The bromocarbons are a group of volatile compounds that are produced naturally in seawater and carry the element, bromine from the ocean reservoir in to the atmosphere. Once in the atmosphere bromine has an important influence on the chemistry taking place there. The major impact of this flux is a reduction in the amount of ozone in the air, which can reduce the potential for the breakdown of harmful greenhouse gases and lead to an increase in the amount of harmful UV light reaching the Earth's surface. Understanding how, when and where these bromocarbon compounds are produced in the marine environment is essential to allow us to predict their impact on the Earth's system. Results from our recent study in the Antarctic show that the bromocarbon compounds bromoform (CHBr3) and dibromomethane (CH2Br2) are produced during a phytoplankton bloom that occurs as the sea-ice breaks up during the summer months (October to May). Blooms such as the one we studied occur all along the area of the Antarctic known as the Western Antractic Peninsula during the summer. If bromocarbon production occurs in all of these blooms, there could be a large sea-to-air flux of bromine during the Antarctic summer which could have an important influence on atmospheric chemistry. In this study, we propose to identify the main biological, chemical and physical processes influencing bromocarbon concentrations in the sea-ice edge phytoplankton blooms and use this knowledge to estimate the potential impact of sea-air bromine flux using mathematical models.