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

OCE-0647446麻省理工学院的一位研究人员建议对铅(铅)、铁(Fe)、锌(锌)及其稳定同位素进行协调研究，以评估人类活动对海洋化学的影响，并提高我们对痕量金属在调节海洋生物地球化学循环中的作用的理解。该项目的具体目标如下：(1)确定微量元素变化、尘埃通量、海洋学和生物变化之间的联系；(2)确定北大西洋西部北大西洋深水铅最大值的空间演化；(3)评估氧最低铁最大值是通过来自非洲西北部海域还原沉积物的铁通量的平流混合向西发展，还是来自浮游生物对浮游生物大量吸收的尘埃铁的原位再矿化；(4)确定铅同位素比值是否可用于确定铅向大西洋东部深部输送的时间尺度；以及(5)评估首次在大西洋进行的公海Fe同位素比值测量，确定我们是否可以区分尘埃Fe和再矿化的生物Fe，并考虑上层海洋的Zn同位素比值是否反映了渐进的生物瑞利分馏作用。为了实现概述的目标，科学家将在选定的BTM和MOSEAN部署上使用系泊水取样器，在BATS和热邮轮上使用MITESS/ATE单机部署，继续百慕大和夏威夷的铅和铁时间序列，并完成对2005年夏季奋进号408号热带大西洋西部邮轮期间收集的铅剖面的分析。此外，还将开展远洋实地工作，以确定热带大西洋铁最大值与浅层氧最低值有关的空间变异性，并在19世纪中叶最古老的东大西洋深水中找到独特的铅同位素比值。最后，对于铁和锌同位素工作，将进行表层和中深海海水铁同位素，北太平洋海水锌同位素剖面，以及秘鲁上升流区域锌同位素生物分馏的研究。然而，预计本科生也将参与这项工作，并与研究生一起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.