Iodine Biogeochemistry in the Southern Ocean

碘可能是气候变化的一个关键因素，因为海洋中的碘排放强烈影响新的气溶胶粒子的形成，从而影响云的形成和辐射平衡。人们对海洋碘排放的来源和机制知之甚少，海水中碘生物地球化学的其他更基本的方面也是如此，例如主要碘物种之间的循环；碘酸盐和碘化物。在这项拟议的工作中，我们将调查南大洋研究较少的水域中碘的生物地球化学。这项工作的中心将是调查南大洋大西洋部分碘物种分布和形态背后的潜在机制。该项目的实地工作部分将在Polarstein ANTXXIV-3 ZERO&DRAKE期间与IPY项目GEOTRACES合作进行。在这次巡航期间，将研究海水中铁浓度和浮游植物丰度的梯度，包括沿本初子午线的开阔海域、韦德尔海和德雷克海峡以及几个南极岛屿附近的海水中碘物种的形态和分布。实验室工作将侧重于碘化物形态形成的动力学方面，特别是在南大洋水域发现的环境温度下，通过非生物和生物机制还原碘酸盐。拟议的工作将使用最先进的技术来确定海水中的碘物种，这些技术可以在海上进行：(1)阴极溶出伏安法测量碘。(2)长光程分光光度法测碘。在此基础上，对南大洋硅藻物种进行的培养实验将审查和确定对减少碘酸盐和氧化碘化物至关重要的过程。积累的数据将纳入南大洋碘生物地球化学综合模型。

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.