Digging into Soil Carbonate Formation Processes with Triple Oxygen Isotopes

用三重氧同位素深入研究土壤碳酸盐的形成过程

• 批准号: 2122023
• 负责人: Naomi Levin
• 金额: $ 36.07万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2122023&HistoricalAwards=false
• 关键词: Digging; into; Soil; Carbonate; Formation

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Drylands are water-limited ecosystems that cover 40% of Earth's land surface, are home to 2.5 billion people, and are particularly vulnerable to climate change. Carbonate-forming soils, which are common in dryland ecosystems, are important components to the carbon cycle and critical for building records of past climate, but we do not fully understand how they form. This project will investigate the role of water loss from soils as a mechanism for soil carbonate formation. The team will use the three stable isotopes of oxygen, 16O, 17O and 18O, to distinguish between the role of soil water loss via evaporation vs. uptake by plants. While ratios of oxygen isotopes 18O to 16O are commonly used to study soil carbonate and other climate archives, 17O, the 3rd stable oxygen isotope, is far less abundant and has not been fully developed for studies of soils and past climate. This project will develop triple oxygen isotope distributions (comparing all three oxygen isotopes) as tools for investigating soil formation processes in modern and ancient climates through field work across major ecological and aridity gradients in the U.S., including sites in the Drylands Critical Zone Network. The results from this work will improve reconstructions of past climate, with particular attention to detecting drought and aridity in ancient ecosystems. The project will provide training for a postdoctoral scientist in preparation for building her own analytically intensive laboratory and research program, filling the need for more laboratories and PIs who are capable of making analytically challenging triple oxygen isotope measurements. Training of undergraduates at three institutions will be integral to the field components to this research. The undergraduate component to this work will broaden participation in the geosciences and include recruiting participants through the University of Michigan Earth Camp program.Increased variability in the hydrologic cycle due to modern climate change will potentially lead to feedbacks in water and carbon storage. At the same time, modern climate change enhances the need for tools to identify water stress in ancient climates as analogues for our future world. This project uses triple oxygen isotopes to evaluate the role of evaporation and transpiration in soil dewatering during soil carbonate formation in the U.S. This work will include a study of triple oxygen isotopes in carbonate in soils and in their parent meteoric waters. Our field work will focus on four sites in the US that include the hyper-arid Mojave Desert of California, the subhumid deciduous forest in Michigan, and two intermediate sites in arid environments, Reynolds Creek, Idaho and the Jornada Basin in New Mexico. The outcomes of this work will include tools for stripping away the effects of evaporation on pedogenic carbonate delta 18O to reveal meteoric water delta 18O, which is the holy grail for paleohydrology and paleoaltimetry. This work will improve our understanding of how abiotic and biotic processes each control pedogenic carbonate formation; this understanding is necessary to be able to predict how and where pedogenic carbonate will precipitate in natural and agricultural soils under the predicted increased hydrological variability, with implications for carbon sequestration and water storage in dryland critical zones.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.

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。旱地是水资源有限的生态系统，覆盖了地球陆地表面的40%，是25亿人的家园，特别容易受到气候变化的影响。形成碳酸盐的土壤在旱地生态系统中很常见，是碳循环的重要组成部分，对建立过去气候记录至关重要，但我们并不完全了解它们是如何形成的。该项目将研究土壤水分流失作为土壤碳酸盐形成机制的作用。该团队将使用氧的三种稳定同位素，16O、17O和18O，来区分土壤水分通过蒸发损失和植物吸收的作用。氧同位素18O和16O的比值通常用于研究土壤碳酸盐和其他气候档案，而第三种稳定的氧同位素17O的丰度要低得多，尚未完全用于土壤和过去气候的研究。该项目将开发三种氧同位素分布（比较所有三种氧同位素），作为研究现代和古代气候下土壤形成过程的工具，通过在美国主要生态和干旱梯度（包括旱地关键带网络）的现场工作。这项工作的结果将改进对过去气候的重建，特别关注探测古代生态系统中的干旱和干旱。该项目将为博士后科学家提供培训，为建立自己的分析密集型实验室和研究项目做准备，以填补对更多实验室和pi的需求，这些实验室和pi能够进行具有分析挑战性的三氧同位素测量。三所院校的本科生培训将是本研究的实地组成部分的组成部分。这项工作的本科生部分将扩大对地球科学的参与，包括通过密歇根大学地球营项目招募参与者。现代气候变化导致的水文循环变异性的增加将潜在地导致水和碳储量的反馈。与此同时，现代气候变化增加了对工具的需求，以识别古代气候中的水压力，作为我们未来世界的类似物。该项目使用三氧同位素来评估美国土壤碳酸盐形成过程中蒸发和蒸腾在土壤脱水中的作用。这项工作将包括研究土壤中碳酸盐及其母体大气水中的三氧同位素。我们的野外工作将集中在美国的四个地点，包括加利福尼亚州极度干旱的莫哈韦沙漠，密歇根州半湿润的落叶森林，以及两个干旱环境中的中间地点，爱达荷州的雷诺兹溪和新墨西哥州的约纳达盆地。这项工作的成果将包括剥离蒸发对成土碳酸盐三角洲18O的影响的工具，以揭示大气水三角洲18O，这是古水文学和古高度计的圣杯。这项工作将提高我们对非生物和生物过程如何各自控制成土碳酸盐岩形成的理解；这种理解对于能够预测在预测的水文变异性增加的情况下，成土碳酸盐将如何以及在何处在自然和农业土壤中沉淀是必要的，这对旱地关键地带的碳固存和水储存具有影响。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。

项目成果

Triple oxygen isotope compositions of globally distributed soil carbonates record widespread evaporation of soil waters

• DOI: 10.1016/j.gca.2023.06.034
• 发表时间: 2023-08
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: J. Kelson;T. Huth;B. Passey;N. Levin;S. Petersen;P. Ballato;E. Beverly;D. Breecker;G. Hoke;A. Hudson;Haoyuan Ji;A. Licht;Erik J. Oerter;J. Quade