Reconstructing Pliocene-Pleistocene paleoenvironmental conditions and biogeochemical element cycling in the Gulf of Alaska (Northeast Pacific)

重建阿拉斯加湾（东北太平洋）上新世-更新世古环境条件和生物地球化学元素循环

• 批准号: NE/L002639/1
• 负责人: Christian Maerz
• 金额: $ 1.76万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FL002639%2F1
• 关键词: Reconstructing; Pliocene; Pleistocene; paleoenvironmental; conditions

Studying marine sediments is one of the best methods to assess changes to the environment and climate that affected certain regions of our ocean in the past, ultimately leading to a better understanding of Erath's climate system as a whole, and potentially a better idea of the effects of future climate change. In the context of climate change, the cycling of carbon and other essential elements between the atmosphere, the biosphere, the ocean and marine sediments is of major importance. Marine primary producers sequester carbon dioxide from the atmophere into their biomass, and ultimately into marine sediments at the seafloor. There is a delicate balance between sources, sinks, and transformations between a number of essential elements (like carbon, phosphorus, iron) that controls how much atmospheric carbon gets buried in the seafloor. Reconstructing this balance, and its linkage to global climate changes, can be done by analysing the archives of past environmental conditions using inorganic geochemical methods. This is one of the major aims of the Integrated Ocean Drilling Program, dedicated to provide high-quality marine sediment records covering critical intervals in Earth's climatic history from various parts of the world ocean.Within the context of this global and longterm undertaking, IODP Expedition 341 will recover long sediment cores from the currently understudied marginal Northeast Pacific. The selected drill sites cover a range of water depths and distances to the coast, which will hopefully allow for paleoenvironmental reconstructions along a depth/distance transect. In addition, the Gulf of Alaska is located close to the Bering Sea, where the PI of this project participated in IODP Expedition 323 and in the following studied various paleoenvironmental and biogeochemical parameters than can ideally be compared to respective data from the Gulf of Alaska. The sediments to be recovered there are well suited to tackle a number of highly relevant research questions. First, biogenic opal productivity in the North Pacific is generally believed to have "crashed" at the Pliocene-Pleistocene boundary, but new data from the Bering Sea contradict this widely accepted assumption. Comparable data from the Gulf of Alaska will provide additional information for this discussion, and will give us a better idea of the development of primary productivity across the wider North Pacific in response to northern hemisphere cooling. Second, primary productivity in the Gulf of Alaska is Fe-limited, and both glacial dust storms as well as diagenetic processes on the shelf have been invoked to deliver the urgently needed reactive Fe to the open marine phytoplankton communities. Studying the distribution of various Fe, but also P phases in the sediments will allow us to estimate how and when these Fe sources were active in the past, and how they affected primary productivity and organic carbon burial. Third, the North Pacific margin has experienced strong variations in bottom water redox conditions over the past millions of years, likely related to enhanced export of organic carbon to the seafloor and/or changes in the degree of deepwater ventilation. Using trace metal records, we will reconstruct the redox history of different water masses in the Gulf of Alaska. Fourth, the Gulf of Alaska sediments provide an ideal location to study the sources, sinks and biogeochemical cycling of various P phases that were newly identified in the Bering Sea. Recognition of these P phases and their involvement into biogeochemical cycles might change our current understanding of the global marine P cycle, and might be instrumental for better global biogeochemical models.

研究海洋沉积物是评估过去影响我们海洋某些地区的环境和气候变化的最佳方法之一，最终使人们对埃拉斯（Erath）的气候系统整体有了更好的了解，并有可能更好地了解未来气候变化的影响。在气候变化的背景下，碳，生物圈，海洋和海洋沉积物之间的碳和其他基本要素的循环至关重要。海洋初级生产商将二氧化碳从增压器静止到其生物质中，并最终变成海底的海洋沉积物。来源，水槽和多个基本要素（例如碳，磷，铁）之间的转化之间存在微妙的平衡，该要素控制着埋在海底的大气碳。可以通过使用无机地球化学方法分析过去环境条件的档案来重建这种平衡及其与全球气候变化的联系。这是综合海洋钻井计划的主要目的之一，致力于提供高质量的海洋沉积物记录，涵盖了来自世界各地的地球气候历史上的关键间隔。在这项全球和长期企业的背景下，IODP Expedition 341将从目前被熟悉的东北太平洋杂货中恢复长期的沉积物核心。选定的钻头覆盖了一系列水深和沿海岸的距离，这将有望允许沿深度/距离样带进行古环境重建。此外，阿拉斯加湾位于白令海附近，该项目的PI参与了IODP Expedition 323，在以下研究中，研究了各种古环境和生物地球化学参数，而不是理想地将其与阿拉斯加湾的各自数据相比。要回收的沉积物非常适合解决许多高度相关的研究问题。首先，通常认为北太平洋的生物蛋白石生产力在上新世 - 尤迪近代边界处“崩溃”，但白令海的新数据与这个被广泛接受的假设相矛盾。来自阿拉斯加湾的可比数据将为本讨论提供其他信息，并将使我们更好地了解整个北太平洋的主要生产力，以响应北半球的冷却。其次，阿拉斯加湾的主要生产力是有限限制的，并且已经调用了架子上​​的冰川沙尘暴以及架子上的成岩化过程，以将急需的反应性FE运送到开放的海洋浮游植物社区。研究各种FE的分布，但在沉积物中的P阶段也将使我们能够估计这些FE来源过去以及何时何时活跃，以及它们如何影响原发性生产力和有机碳埋葬。第三，在过去的数百万年中，北太平洋的边缘在底水氧化还原条件上经历了巨大的变化，这可能与有机碳的出口增强有关和/或深水通风程度的变化有关。使用痕量金属记录，我们将重建阿拉斯加湾不同水质量的氧化还原病史。第四，阿拉斯加沉积物的湾提供了研究各种P阶段的来源，水槽和生物地球化学循环的理想位置，这些P阶段在白令海新近鉴定出来。对这些P阶段的认识及其参与生物地球化学周期可能会改变我们对全球海洋P周期的当前理解，并且可能对更好的全球生物地球化学模型具有重要作用。

项目成果

Cordilleran ice-sheet growth fueled primary productivity in the Gulf of Alaska, northeast Pacific Ocean

• DOI: 10.1130/g39904.1
• 发表时间: 2018-04
• 期刊: Geology
• 影响因子: 5.8
• 作者: J. Müller;O. Romero;E. Cowan;E. McClymont;M. Forwick;H. Asahi;C. März;C. Moy;I. Suto;A. Mix;J. Stoner

Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska

• DOI: 10.1073/pnas.1512549112
• 发表时间: 2015-12-08
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Gulick, Sean P. S.;Jaeger, John M.;Swartz, John M.
• 通讯作者: Swartz, John M.