Spatial and Temporal Variability of Pb, Fe, Zn, and their Stable Isotope Ratios in the Tropical and Subtropical Atlantic and Pacific Oceans

马萨诸塞州理工学院的研究员OCE-0647446建议开展铅（Pb）、铁（Fe）、锌（Zn）及其稳定同位素的协调研究，以评估人类活动对海洋化学的影响，提高我们对痕量金属在调节海洋地球化学循环中作用的认识。 该项目的具体目标如下：（1）确定微量元素变化、尘埃通量、海洋和生物变化之间的联系;（2）查明北大西洋西部北大西洋上层深水铅最大值的空间演变;（3）评估氧最小值铁最大值是否通过来自非洲西北部还原沉积物的铁通量的平流混合向西发展，（4）确定Pb同位素比值是否可用于建立Pb向东大西洋深海迁移的时间尺度;和（5）评估第一次在大西洋公海测量铁同位素比值，并确定我们是否可以区分灰尘铁从稀土，矿化生物铁，并考虑是否上层海洋锌同位素比值反映了进步的生物瑞利分馏。 为了实现所列目标，科学家将继续使用选定的BTM和MOSEAN部署的系泊水采样器、BATS和HOT巡航的单单元MITESS/ATE部署，对百慕大和夏威夷的铅和铁时间序列进行分析，并完成对2005年夏季奋进408号在热带大西洋西部巡航期间收集的铅剖面的分析。 此外，将进行海上实地考察，以建立与浅氧最小值相关的热带大西洋Fe最大值的空间变异性，并在最古老的东大西洋深水中找到独特的世纪中期Pb同位素比。 最后，关于铁和锌同位素的工作，将进行表层和中层沃茨的铁同位素、北太平洋海水锌同位素剖面图以及秘鲁上升流区域锌同位素的逐步生物分馏研究，关于更广泛的影响，该项目将资助一名研究生。 然而，预计本科生也将参与这项工作，并与研究生一起沿着接受如何使用最先进的仪器获得高质量痕量金属和同位素数据的培训。

OCE-0647446A researcher from Massachusetts Institute of Technology proposes to carry out coordinated studies of lead (Pb), iron (Fe), zinc (Zn), and their stable isotopes to assess the anthropogenic impact on ocean chemistry and improve our understanding of the role of trace metals in regulating ocean biogeochemical cycles. The specific goals of this project are the following: (1) determine links between trace element variability, dust flux, oceanographic and biological changes; (2) ascertain the spatial evolution of the upper North Atlantic Deep Water Pb maximum in the western North Atlantic; (3) evaluate whether the oxygen-minimum Fe-maximum develops westward via advective mixing from Fe fluxes from reducing sediments off NW Africa, or from in-situ re-mineralization of luxury-uptake dust Fe by plankton; (4) determine whether Pb isotope ratios can be used to establish the time scale of Pb transport into the eastern deep Atlantic; and (5) assess the first open-ocean measurements of Fe isotope ratios in the Atlantic and determine whether we can distinguish dust Fe from re-mineralized biological Fe and consider whether upper ocean Zn isotope ratios reflect progressive biological Rayleigh fractionation. To attain the outlined goals, the scientist will continue the Bermuda and Hawaii Pb and Fe time-series using the moored water sampler on selected BTM and MOSEAN deployments, the single-unit MITESS/ATE deployments on BATS and HOT cruises, and complete the analysis of Pb profiles collected during the summer 2005 Endeavor 408 cruise in the western tropical Atlantic. In addition, sea-going fieldwork will be carried out to establish the spatial variability of the tropical Atlantic Fe maximum associated with the shallow oxygen minimum, and to find unique mid-19th century Pb isotope ratios in the oldest east Atlantic deep water. Lastly, for the Fe and Zn isotope work, seawater Fe isotopes from surface and mid-depth waters, a seawater Zn isotope profile from the North Pacific, and a study of the progressive biological fractionation of Zn isotopes in the Peruvian upwelling region will be done.As regards broader impacts, one graduate student will be supported by this project. However, it is anticipated that undergraduate students will also be included in the work and be trained along with the graduate student on how to obtain high quality trace metal and isotopic data using state of the art instrumentation.