SGER: Paleoceanographic Evidence for Changes in Ocean Circulation and the Ecological Effects of Iron Fertilization in the Northeast Pacific (0-20 ka)

该项目将研究最后一次冰期-间冰期过渡期间东北太平洋海洋环流和生物生产力的演变。已发表的模型结果引用了冰川时期通风不佳的深水团的存在，富含溶解的无机碳，以帮助解释海洋在过去影响大气二氧化碳变异性方面的作用。到目前为止，还没有关于上一次冰川时期北太平洋环流和水柱结构的清晰图景。这一研究项目旨在回答冰川-间冰期过渡期间北太平洋海洋学的基本问题。这些问题包括(1)东北太平洋冰期期间中间水是否像西北太平洋那样渗透到更深的深度；(2)上一次冰期期间东北太平洋深水的年龄是否更大；以及(3)冰川/间冰期铁输入的变化是否影响北太平洋硅藻的生产？PI建议对美国西北部大陆边缘2000米处上升的半深海沉积物岩芯进行多代理研究。将分析冰川时代沉积物的放射性碳年龄(使用海底有孔虫)和自生微量金属含量，以量化氧化还原条件(U、Re、Mo)。将对卡斯卡迪亚盆地岩心和ODP882号站点的硅藻进行硅同位素分析，该站点位于北太平洋一个已证实的铁限制区域，将用于揭示北太平洋新型硅同位素代理的潜力。拟议的研究包括为威斯康星大学海洋学院的一名博士后研究员和一名本科生的专业和科学发展提供资金。

This project will study the evolution of ocean circulation and biological productivity in the Northeast Pacific during the last glacial-interglacial transition. Published model results invoke the existence of a less well-ventilated, deep water mass enriched in dissolved inorganic carbon during glacial periods in order to help explain the ocean's role in influencing atmospheric pCO2 variability in the past. A clear picture of North Pacific circulation and water column structure during the last glacial period has not been produced to date. This research project seeks to answer fundamental questions about North Pacific oceanography during the glacial-interglacial transition. These include (1) did intermediate water penetrate to greater depths during glacials in the NE Pacific as they did in the NW Pacific; (2) was the age of deep waters in the NE Pacific greater during the last glacial period; and (3) did glacial/interglacial changes in iron input influence North Pacific diatom production? The PI proposes a multiproxy study of a hemipelagic sediment core raised from 2000 meters on the continental margin off the Northwestern United States. Glacial age sediment will be analyzed for its radiocarbon age (using benthic foraminifera) and authigenic trace metal content to quantify redox conditions (U, Re, Mo). Silicon isotope analyses will be conducted on diatoms from both the Cascadia Basin core and from ODP Site 882, which is situated in a demonstrated iron-limited region of the North Pacific, and will be used to shed light on the potential for the novel silicon isotope proxy in the North Pacific. The proposed research includes funds for the professional and scientific development of a postdoctoral researcher and an undergraduate student in the UW School of Oceanography.