EAGER: Constraining the Y-axis: Towards Quantitative Constraints for Precipitation and Temperature Using Speleothem Isotope and Trace Element Data

该项目利用早期探索性研究概念基金（EAGER）项目资助的资金，重点研究如何利用质谱分析和数据分析方面的最新进展，从古气候记录中产生温度和降水的定量测量。初步的分析结果表明，碳酸盐中88锶/86锶的比例对温度的变化很敏感。这种理想的关系由于有限的实验数据而变得复杂，这些数据表明其他因素，如生长动力学可能在该值中起作用。研究人员使用高温和低温碳酸盐进行了一些初步测量，数据令人鼓舞，88Strontium/86Strontium与温度之间似乎存在很强的关系。然而，目前还没有数据能令人信服地证明与古气候有关的温度范围内的温度依赖性。热电离质谱（TIMS）的最新进展与“双尖峰”方法相结合，可以提供足够的准确度和精度来验证这一想法。此外，斯坦顿堡洞穴中的石笋在末次冰期到全新世早期的气候波动中生长，是分析的理想选择。锶同位素工作将在一个拥有新一代放大器的实验室中进行，该放大器将有可能获得非常准确和精确的88锶/86锶比率，足以在与古气候相关的尺度上解决温度的潜在变化。研究人员还将设计一个可以容纳长石笋样品的样品室。该项目的另一个有希望的方面是，使用新型准分子激光耦合电感耦合等离子体质谱（ICP-MS）仪器在高通量和高质量元素数据方面的综合技术成就，以及使用机器学习查看数据的新方法。研究人员的初步结果表明，一些微量元素，特别是碱和碱土元素，可能随着稳定同位素的变化而相干变化，从而为机器学习应用提供了所需的多维数据。这些活动在科学上是重要的，并且很好地符合EAGER项目潜在的变革性、高风险但潜在的高回报的研究属性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project uses funds, under the auspices of the EArly Concept Grant For Exploratory Research (EAGER) program, to focus on ways to take advantage of recent advances in mass spectrometry and data analysis in order to produce quantitative measures of temperature and precipitation from the paleoclimate record.An initial analytical finding suggests that the 88Strontium/86Strontium ratio in carbonates is sensitive to changes in temperature. This ideal relationship has been found to be complicated by limited experimental data that suggest that other factors, such as growth kinetics may play a role in this value. The researcher made some initial measurements using high temperature and low temperature carbonates and the data are encouraging to the extent that there seems to be a strong relationship between 88Strontium/86Strontium and temperature. There is no data on hand, however, to convincingly demonstrate temperature dependence in the range of temperature relevant for paleoclimate. Recent advances in thermal ionization mass spectrometry (TIMS) coupled with the "double spike" method could allow enough accuracy and precision to test the idea. In addition, stalagmites from Fort Stanton Cave that grew through the full climate swings that took place from the Last Glacial to the Early Holocene are ideal for analysis and are in-hand. The Strontium isotopic work will be attempted in a laboratory that houses a new generation of amplifier that would make it possible to obtain very accurate and precise 88Strontium/86Strontium ratios, sufficient to resolve potential changes in temperature at a scale relevant for paleoclimate. The researcher will also work on the design of a sample chamber that can accommodate long stalagmite samples.Another aspect of the project that holds promise is the combined technical achievements in high-throughput and high-quality elemental data using newer excimer lasers coupled to inductively coupled plasma mass spectrometry (ICP-MS) instruments and new ways to look at data using machine learning. Initial results by the researcher show that some trace elements, especially alkali and alkali-earth elements, may coherently vary with stable isotopes, thus providing the multidimensional data needed for machine learning applications. The activities are scientifically important and fit well into the potentially transformative, high-risk but potential high payoff research attributes of the EAGER program.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.