GEOTRACES Arctic Section: Diagnosing the unique silicon isotope composition of the Arctic Ocean

GEOTRACES 北极部分：诊断北冰洋独特的硅同位素组成

• 批准号: 1434305
• 负责人: Mark Brzezinski
• 金额: $ 50.09万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434305&HistoricalAwards=false
• 关键词: GEOTRACES; Arctic; Section; Diagnosing; unique

An investigator will participate in the 2015 U.S. GEOTRACES Arctic Ocean expedition and measure silicon isotopes composition of silicic acid in seawater samples, as well as diatoms and sea ice. In common with other multinational initiatives in the International GEOTRACES program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Some trace elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. As silicon is a key component of diatom shells, the measurement of their concentrations in this study can provide an important indicator of primary productivity, both in the present day, as well as past oceans. The project will provide training for undergraduate students and a post-doctoral researcher in silicon chemistry, as well as include outreach to K-12 students.The silicon isotope proxy is increasingly being used to assess the role of diatoms and silicic acid supply to past shifts in ocean productivity and their role in Earth's climate. Application of the proxy requires knowledge of the silicon isotopic composition of ventilating water masses. Uncertainty in these values translates directly into uncertainty in the level of productivity implied by the proxy. The growing global data set of silicon isotopes in marine waters suggest that silicon isotopes in subsurface waters are not uniform, but vary systematically driven by interactions between silicon isotope fractionation, the biological pump and thermohaline circulation. In addition, significant anomalies exist between model predictions and observations. In this study, researchers will test hypotheses regarding the origin of this signal and the mechanisms controlling silicon isotope distributions within the Arctic Ocean by greatly expanding the silicon isotope data set for this region. The overarching hypothesis to be tested is that silicon isotope distributions are controlled by the coupling of silicon fractionation during silica production and during silica dissolution to the biological pump and to the meridional overturning circulation.

一名研究人员将参加2015年美国北极海洋探险队，并测量硅酸在海水样品中以及硅藻和硅冰地区的硅同位素组成。美国北极探险队的目标是与国际地理计划计划中的其他跨国公司计划相同，是确定过程并量化流量，以控制海洋中关键的微量元素和同位素的分布，并确定这些分布对不断变化环境条件的敏感性。一些痕量元素对生命至关重要，另一些是已知的生物毒素，而另一些则很重要，因为它们可以用作海洋中各种物理，化学和生物过程的示踪剂。由于硅是硅藻壳的关键组成部分，因此本研究中其浓度的测量可以为当今的主要生产力以及过去的海洋提供重要的指标。该项目将为本科生和硅化学的博士后研究人员提供培训，并包括向K-12学生提供外展。代理的应用需要了解通风水质量的硅同位素组成。这些值的不确定性直接转化为代理隐含生产率水平的不确定性。在海水中，硅同位素的全球数据集不断增长，表明地下水域中的硅同位素不是均匀的，而是由硅同位素分馏，生物泵和热盐循环的系统驱动的。此外，模型预测和观测值之间存在明显的异常。在这项研究中，研究人员将通过大大扩展该区域的硅同位素数据集来检验有关该信号起源的假设以及控制北极海洋中硅同位素分布的机制。要测试的总体假设是，硅同位素分布是通过硅生产过程中硅分馏以及二氧化硅溶解至生物泵和子午线倾覆循环的控制来控制的。