Iodine Biogeochemistry in the Southern Ocean

碘可能是气候变化的一个关键因素，因为来自海洋的碘排放强烈影响新气溶胶粒子的形成，从而影响云的形成和辐射平衡。人们对海洋中碘排放的来源和机制知之甚少，对海水中碘地球化学的其他更基本的方面也知之甚少，如主要碘物质（碘酸盐和碘化物）之间的循环。在拟议的工作中，我们将调查碘在研究不足的南大洋沃茨的地球化学。这项工作的核心将是调查南大洋大西洋部分碘物种分布和形态形成背后的基本机制。该项目的现场工作部分将在Polarstern ANTXXIV-3 ZERO&DRAKE期间与IPY项目GEOTRACES合作进行。在这次航行中，将检查海水中铁浓度和浮游植物丰度梯度上碘物种的形态和分布;范围从本初子午线沿着的开阔海域、威德尔海和德雷克海峡以及几个南极岛屿附近。实验室工作将侧重于碘化物形态形成的动力学方面，特别是在南大洋沃茨的环境温度下通过非生物和生物机制减少碘酸盐。拟开展的工作将使用可在海上进行的测定海水中碘物质的最新技术：（1）用于测量碘化物的阴极溶出伏安法。(2)长光程分光光度法测定碘酸根。除此之外，南大洋硅藻物种的培养实验将检查和识别对碘酸盐还原和碘化物氧化重要的过程。积累的数据将纳入南大洋碘地球化学综合模型。

Iodine is potentially a key element for climate change as iodine emissions from the ocean strongly influence the formation of new aerosol particles with impacts on cloud formation and radiative balances. The source and mechanism of iodine emissions from the ocean is poorly understood as are other more fundamental aspects of iodine biogeochemistry in seawater such as the cycling between the major iodine species; iodate and iodide. In the proposed work we will investigate the biogeochemistry of iodine in the poorly studied waters of the Southern Ocean. Central to this work will be investigations into the underlying mechanism behind the distribution and speciation of iodine species in the Atlantic sector of the Southern Ocean. The field work component of this project will be performed during Polarstern ANTXXIV-3 ZERO&DRAKE in cooperation with the IPY project GEOTRACES. During this cruise the speciation and distribution of iodine species will be examined across gradients of iron concentration and phytoplankton abundance in seawater; ranging from an open ocean region along the prime meridian, the Weddell Sea and Drake Passage and near several Antarctic islands. Laboratory work will focus on kinetic aspects of the speciation of iodide, in particular the reduction of iodate by abiotic and biotic mechanism, at the ambient temperatures found in Southern Ocean waters. The proposed work will be performed using state of the art techniques for the determination of iodine species in seawater that can be performed at sea: (1) Cathodic stripping voltammetry for the measurement of iodide. (2) Long path length spectrophotometry for the determination of iodate. Further to this culture experiments with Southern Ocean diatom species will examine and identity processes important for the reduction of iodate and oxidation of iodide. The accumulated data will be incorporated into a comprehensive model for iodine biogeochemistry in the Southern Ocean.