Interactions of Cobalt and Iron with in situ Cyanobacterial Physiology in the South Atlantic and the Benguela Upwelling Region

海洋水体中溶解的钴和铁具有极低浓度、氧化还原化学、低溶解度和被海洋微生物利用的微量营养元素等地球化学特征。近年来，由于铁在海洋和沿海上升流环境中限制浮游植物生产力的作用，近年来一直是研究的重点。对钴的研究要少得多，但最近的数据表明，钴在影响某些地理区域的初级生产力或浮游植物群落组成方面可能很重要。在这个项目中，伍兹霍尔海洋研究所的研究人员将应用最先进的地球化学和分子生物学技术来研究这两种微量金属在南大西洋的生物地球化学循环。2007年将有27天的航行前往南大西洋，研究钴和铁的生物地球化学，重点是四个主要假设：1)即使在风成为主的环境中，大通量的不稳定钴也与上升流系统有关。2)由于微量元素利用和快速再矿化，钴和磷酸盐在（且仅在）地表水中表现出相关性。相关性的斜率取决于钴的化学形态。(3)亚热带和热带南大西洋赤霉病种群的缺失是由铁限制引起的。4)根据加利福尼亚和秘鲁上升流的工作，西南非洲本格拉上升流的初级生产力可能是铁有限的或铁钴有限的。更广泛的影响-除了增加我们对数据覆盖较少的地区两种重要微量金属（铁和钴）的生物地球化学的了解外，该项目还将支持Co应力分析的发展，该分析将传播给海洋学界。本课题将完成一名研究生的论文工作，并开始另一名研究生的工作。这些学生将参与分析测量和分子研究。三名本科生研究员也将在暑期实习期间从事分子研究。小型学院中代表性不足的群体的学生将被优先考虑，这些学校通常不提供动手研究的机会。

ABSTRACTOCE-0452883The geochemistries of dissolved cobalt and iron in the oceanic water column share several characteristics such as extremely low concentrations, redox chemistry, low solubility, and utilization as micronutrients by marine microbes. Iron has been the subject of considerable research focus in recent years due to its role in limiting phytoplankton productivity in oceanic and coastal upwelling environments. Cobalt has been much less studied, but recent data shows it may be important in influencing primary productivity or phytoplankton community composition in certain geographical areas. In this project, researchers at the Woods Hole Oceanographic Institution will apply state-of-the-art geochemical and molecular biological techniques to study the biogeochemical cycling of these two trace metals in the South Atlantic. There will be 27-day 2007 cruise to the south Atlantic to study cobalt and iron biogeochemistry focusing on four major hypotheses: 1) Large fluxes of labile cobalt are associated with upwelling systems even in Aeolian dominated environments. 2) Cobalt and phosphate show correlations in (and only in) surface waters due to micronutrient utilization and rapid remineralization. The slope of the correlation is dependent on the chemical speciation of cobalt. 3) The absence of Trichodesmium populations in the subtropical and tropical South Atlantic is caused by iron limitation. 4) Based on work from the California and Peru Upwelling regimes, primary productivity in the Benguela upwelling regime off of South West Africa may be iron limited or iron-cobalt colimited. Broader Impacts - In addition to increasing our understanding of the biogeochemistry of two important trace metals (Fe and Co) in a region with little data coverage, this project will support the development of a Co stress assay that will be disseminated to the oceanographic community. This project will conclude the thesis work of one graduate student and initiate the work of another. These students will partake in analytical measurements and molecular studies. Three undergraduate research fellows will also work on molecular studies during summer internships. Priority will be given to students from underrepresented groups at small colleges that typically do not offer hands-on research opportunities.