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

本项目将研究末次冰期-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。已发表的模式结果援引了在冰期存在一种不太通气、富含溶解无机碳的深水团块，以帮助解释海洋在过去影响大气二氧化碳分压变化方面的作用。最后一次冰期北太平洋环流和水柱结构的清晰图像至今尚未产生。本研究项目旨在回答冰期-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)在东北太平洋的冰川期间，中间水是否像在西北太平洋那样渗透到更深的地方；(2)末次冰期东北太平洋深水年龄较大；(3)冰期/间冰期铁输入的变化是否影响北太平洋硅藻的生产？PI提议对美国西北部大陆边缘从2000米处升起的半深海沉积物岩心进行多代理研究。冰川时代沉积物将分析其放射性碳年龄（使用底栖有孔虫）和自生微量金属含量来量化氧化还原条件（U, Re, Mo）。硅同位素分析将对Cascadia盆地岩芯和ODP站点882的硅藻进行，该站点位于北太平洋的铁限制区域，并将用于阐明北太平洋新型硅同位素代理的潜力。建议的研究包括资助一名博士后研究员和一名西澳大学海洋学院本科生的专业和科学发展。

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.