Developing bottom water temperature (BWT) calibrations using elemental ratios in benthic foraminifera

使用底栖有孔虫的元素比率进行底层水温 (BWT) 校准

• 批准号: 1811305
• 负责人: Delia Oppo
• 金额: $ 50万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2021-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1811305&HistoricalAwards=false
• 关键词: Developing; bottom; water; temperature; BWT

Data from geological archives such as ice cores, corals, tree rings, and marine and lake sediments reveal past changes in atmosphere and ocean conditions that exceed the range of variability observed during the instrumental era, but the precise mechanisms of past changes are often not well known. Temperature of the subsurface ocean is a key indicator of many ocean processes and accurate estimates would help test many hypotheses of past ocean and climate change. Subsurface temperature in the past is generally estimated from elemental ratios, especially magnesium/calcium (Mg/Ca) of benthic foraminifera but there are many lines of evidence that the incorporation of Mg (and other metals) into the shells of benthic foraminifera is influenced in the process of shell construction (biomineralization). This research investigates the controls on Mg/Ca and other elemental ratios in benthic foraminifera with the goal of providing new calibrations to estimate subsurface temperature in the past. Improved calibrations will enable subsurface temperature estimates that can be used to test hypothesis of past climate change, as well as test the ability of the same numerical models that are used to predict future climate change to reproduce estimates of subsurface temperature in the past. The project benefits from a collaboration between a paleoceanographer and a geochemist. A postdoctoral scientist will participate in the research, which also includes community participation in data syntheses. These data syntheses will be made publicly available through NOAA's World Data Services for Paleoclimatology, and results will be described for general audiences on participants' web pages.The team will generate new benthic elemental data from a wide range of ocean environments, with the goal of isolating the control of temperature and carbonate chemistry on elemental ratios, especially Mg/Ca and lithium/calcium (Li/Ca). A biomineralization model will provide a unifying framework and more quantitative constraints on the environmental factors controlling the elemental ratios, and context for new multi-element (e.g., Mg/Li) calibrations. New calibrations will be tested with data from sediment core-top samples from regions omitted from the calibrations, and by assessing whether vertical and horizontal temperature trends in the glacial and deglacial ocean are reasonable. Past temperature estimates will be compared to predictions from climate model simulations. Community participation in both the data synthesis and data-model comparisons will be requested through a paleoclimate listserv. While model-data synthesis will focus on the last 22,000 years, the results will provide improved calibrations to estimate subsurface temperature over a much longer time scale.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

来自地质档案的数据，如冰芯、珊瑚、树轮、海洋和湖泊沉积物，揭示了过去大气和海洋条件的变化，超出了仪器时代观察到的可变性范围，但过去变化的确切机制往往不是很清楚。次表层海洋的温度是许多海洋过程的关键指标，准确的估计将有助于检验过去海洋和气候变化的许多假说。过去，海底有孔虫的表层温度通常是通过元素比值，特别是镁/钙(mg/Ca)来估算的，但有许多证据表明，镁(和其他金属)进入海底有孔虫壳层的过程会在贝壳结构(生物矿化)过程中受到影响。本研究旨在探讨底栖有孔虫对镁/钙及其他元素比值的控制，以期为过去估算地下温度提供新的校正方法。改进的校准将使地下温度估计能够用于检验过去气候变化的假说，并测试用于预测未来气候变化的相同数值模型重现过去地下温度估计的能力。该项目得益于一位古海洋学家和一位地球化学家的合作。一名博士后科学家将参与这项研究，该研究还包括社区参与数据合成。这些数据合成将通过NOAA的世界古气候学数据服务公开，结果将在参与者的网页上向普通观众描述。该团队将从广泛的海洋环境中生成新的海底元素数据，目标是隔离温度和碳酸盐化学对元素比例的控制，特别是镁/钙和锂/钙(Li/Ca)。生物矿化模型将为控制元素比例的环境因素提供统一的框架和更多的定量约束，并为新的多元素(如镁/锂)校准提供背景。新的校准将使用校准遗漏区域的沉积物岩心顶部样本的数据进行测试，并评估冰川和非冰川海洋的垂直和水平温度趋势是否合理。过去的气温估计将与气候模型模拟的预测进行比较。将通过古气候清单服务器请求社区参与数据合成和数据模型比较。虽然模型数据合成将专注于过去22,000年，但结果将提供改进的校准，以估计更长时间范围内的地下温度。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。