Water mass mixing and silicate utilization in the Atlantic Ocean

大西洋的水团混合和硅酸盐利用

• 批准号: 193275278
• 负责人: Professor Dr. Martin Frank
• 金额: --
• 依托单位: Forschungseinheit Paläo-Ozeanographie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/193275278?language=en
• 关键词: Water; mass; mixing; silicate; utilization

The central goal of this proposed study is a detailed investigation of the distribution of dissolved neodymium (Nd), hafnium (Hf) and silicon (Si) concentrations and isotope compositions in the water column of the tropical Atlantic Ocean. Radiogenic Nd and Hf isotopes are powerful geochemical tracers of water mass flow and mixing, as well as of continental inputs and weathering regimes, but there are significant uncertainties concerning the quantitative importance of input sources such as Saharan dust, rivers and exchange with shelf sediments, which currently prevent the use of these isotope systems as quantitative proxies for present and past ocean circulation. Silicon isotopes are a promising tracer for Si utilization by biological activity the surface waters, but the Si isotope distributions are also influenced by water mass mixing. For all these isotopic tracers there is a severe lack of detailed data on their distribution in critical areas of the present day Atlantic Meridional Overturning Circulation (AMOC) in the northwestern and tropical Atlantic, which severely restricts their reliable application as proxy tracers. To remove this gap, full water column profiles were sampled at high resolution and under trace metal clean conditions along the sections of expedition Meteor M81/1 (GEOTRACES Cruise A11, Canaries – Port of Spain, Trinidad and Tobago in February/March 2010) and during RV Pelagia expedition 64PE319/321 (GEOTRACES Cruise A02, Scrabster, Scotland – Fortaleza, Brasil, April - July 2010) in the tropical and western North Atlantic, which will serve as material for the proposed study. The systematic measurement of the isotope composition and concentration of Nd, Hf, and Si will for the first time characterize the factors controlling their water mass signatures and inputs in the tropical Atlantic Ocean and will significantly improve their applicability as proxy tracers for ocean circulation, weathering inputs, and silicate utilisation in the present and past ocean.

本研究的中心目标是详细研究热带大西洋水柱中溶解的钕（Nd）、铪（Hf）和硅（Si）浓度和同位素组成的分布。放射性成因的Nd和Hf同位素是水团流动和混合以及大陆输入和风化机制的强大地球化学示踪剂，但在输入源（如撒哈拉沙尘、河流和与陆架沉积物的交换）的数量重要性方面存在很大的不确定性，这目前阻碍了将这些同位素系统用作当前和过去海洋环流的定量代用物。硅同位素是一种很有前景的地表水生物活性利用硅的示踪剂，但硅同位素分布也受到水质量混合的影响。所有这些同位素示踪剂在现今大西洋经向翻转环流（AMOC）在西北和热带大西洋的关键区域分布的详细资料严重缺乏，这严重限制了它们作为替代示踪剂的可靠应用。为了消除这一差距，在高分辨率和痕量金属清洁条件下，沿着流星M81/1（2010年2月/3月，加那利群岛-西班西班港，特立尼达和多巴哥，GEOTRACES邮轮A11号）和RV Pelagia号探险64PE319/321（2010年4月- 7月，苏格兰斯克拉斯特-巴西福塔莱萨，GEOTRACES邮轮A02号）在热带和北大西洋西部取样了完整的水柱剖面，这将作为建议研究的材料。Nd、Hf和Si的同位素组成和浓度的系统测量将首次表征控制它们在热带大西洋的水团特征和输入的因素，并将显著提高它们作为海洋环流、风化输入和现在和过去海洋硅酸盐利用的替代示踪剂的适用性。