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.

该奖项是根据2021年《美国救援计划法》（公法117-2）全部或部分资助的。旱地是覆盖地球地面40％的水限制生态系统，是25亿人的家园，尤其容易受到气候变化的影响。在旱地生态系统中常见的碳酸盐形成土壤是碳循环的重要组成部分，对于过去气候的建筑记录至关重要，但我们不完全了解它们的形成方式。该项目将研究水损失土壤的作用，作为土壤碳酸盐形成的机制。该团队将使用氧气，16o，17o和18o的三种稳定的同位素来区分通过蒸发与植物吸收的土壤水分流失的作用。虽然18O与16O的氧同位素比率通常用于研究土壤碳酸盐和其他气候档案，但第三稳定的氧同位素17o的丰富度却少得多，并且尚未完全开发用于土壤和过去气候的研究。该项目将开发三氧同位素分布（比较所有三种氧同位素），作为通过在美国的主要生态和干旱梯度（包括旱地关键区域网络）的现代和古代气候研究中研究土壤形成过程的工具。这项工作的结果将改善过去气候的重建，特别注意检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，以准备建立自己的分析密集的实验室和研究计划，从而满足了能够进行分析性挑战性三重氧同位素测量的更多实验室和PI的需求。在三个机构中对本科生的培训将是这项研究的现场组成部分的组成部分。这项工作的本科组成部分将扩大对地球科学的参与，并包括通过密歇根大学地球训练营计划招募参与者。由于现代气候变化而导致的水文周期的变化率很高，可能会导致水和碳存储的反馈。同时，现代气候变化增强了对在古代气候中识别水压力的工具的需求，作为我们未来世界的类似物。该项目使用三重氧同位素来评估美国土壤中碳酸盐形成期间土壤脱水中的作用，这项工作将包括对土壤及其父灭气水中碳酸盐中三重氧同位素的研究。我们的现场工作将集中在美国的四个地点上，包括加利福尼亚的Hyper-Arid Mojave沙漠，密歇根州的亚富裕落叶森林以及干旱环境中的两个中间地点，雷诺兹溪，爱达荷州，爱达荷州和新墨西哥州的Jornada盆地。 这项工作的结果将包括用于剥离蒸发对碳酸盐碳酸盐三角洲18o的影响的工具，以揭示陨石水的三角洲18o，这是用于古水的圣杯和古质量法。这项工作将提高我们对非生物和生物过程如何控制成源碳酸盐形成的理解。这种理解是必须预测在预测的自然和农业土壤中如何以及在何处在水文变异性增加的情况下沉淀的如何以及何处，这对Dryland关键区域的碳固换和水的存储产生了影响。这奖反映了NSF的法定任务，并被认为是通过基金会的知识优点和广泛的crietia crietia crietia crietia criperia crietia criperia crietia criteria criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia rectiria rection the奖项。

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