EAGER: Unraveling riverine sulfate using minor oxygen isotopes

EAGER：使用次要氧同位素解开河流硫酸盐

• 批准号: 1839341
• 负责人: David Johnston
• 金额: $ 10.04万
• 依托单位: Harvard University
• 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: 2018-09-01 至 2020-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1839341&HistoricalAwards=false
• 关键词: EAGER; Unraveling; riverine; sulfate; using

Over geological timescales, weathering reactions involving minerals on the land surface have regulated the amounts of important gases such as oxygen and carbon dioxide in Earth's atmosphere. This award funds research that will explore the potential for a new method to provide constraints on one such reaction in Earth history: the oxidation of the mineral pyrite. Over the geological past, global variation in the amount of pyrite that has been oxidized provides a critical link between Earth's carbon and sulfur cycles, while a record of this history may be preserved by sulfate minerals in marine sediments. The researchers will generate a proof-of-concept data set that takes advantage of information that can be gathered from a rare and difficult-to-measure stable isotope in dissolved and mineral sulfate: 17-oxygen. This novel method will be applied to previously collected and well-characterized water samples from a major river system draining the Himalaya Range. This pilot data set will provide important information about the mechanisms that control the isotopic composition of dissolved sulfate and will help to unravel the record that is preserved in marine sediments. The award will also provide mentoring for a postdoctoral fellow who has contributed to the design and planning of this project and will provide the individual with opportunities for leadership roles within the research group.This award funds the exploration of the potential for a new proxy to quantify geological rates of pyrite oxidation, based on the minor oxygen stable isotope (17-O) preserved in sulfate produced by pyrite oxidation. Because pyrite oxidation both consumes oxygen and generates acidity that dissolves carbonate rocks and produces CO2, it has been suggested that changes in pyrite oxidation rates may have acted to stabilize fluctuations in atmospheric CO2. Although pyrite oxidation is a critical link between Earth's carbon and sulfur cycles, the application of a 17-O proxy in marine sulfate is limited by our understanding of sulfate generation and translation through fluvial systems. This work would begin to narrow this gap by generating a proof-of-concept data set from well-characterized river samples from a major river system draining the Himalaya Range that has already been measured for 34-S and 18-O composition of dissolved sulfate. The researchers will add measurements of the 17O composition of dissolved sulfate from these samples to investigate the potential sources and subsequent recycling of sulfate in downstream floodplains. The riverine 17-O-sulfate data set will provide a rigid framework with which to interpret 17-O records in the marine sulfate record.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.

在地质时间尺度上，涉及陆地表面矿物的风化反应调节了地球大气中氧气和二氧化碳等重要气体的含量。 该奖项资助的研究将探索一种新方法的潜力，以限制地球历史上的一个此类反应：矿物黄铁矿的氧化。 在过去的地质历史中，已氧化的黄铁矿数量的全球变化提供了地球碳和硫循环之间的关键联系，而海洋沉积物中的硫酸盐矿物可能保存了这段历史的记录。 研究人员将生成一个概念验证数据集，该数据集利用从溶解的矿物硫酸盐中稀有且难以测量的稳定同位素：17-氧中收集的信息。 这种新颖的方法将应用于以前从喜马拉雅山脉排水的主要河流系统中收集和充分表征的水样。 该试点数据集将提供有关控制溶解硫酸盐同位素组成的机制的重要信息，并将有助于解开海洋沉积物中保存的记录。该奖项还将为一名博士后研究员提供指导，该博士后研究员对该项目的设计和规划做出了贡献，并将为个人提供在研究小组内发挥领导作用的机会。该奖项资助探索新的量化代理的潜力黄铁矿氧化的地质速率，基于黄铁矿氧化产生的硫酸盐中保存的次要氧稳定同位素（17-O）。由于黄铁矿氧化既消耗氧气，又产生酸性，溶解碳酸盐岩石并产生二氧化碳，因此有人认为，黄铁矿氧化速率的变化可能起到了稳定大气二氧化碳波动的作用。尽管黄铁矿氧化是地球碳和硫循环之间的关键环节，但 17-O 代理在海洋硫酸盐中的应用受到我们对硫酸盐通过河流系统的生成和转化的理解的限制。这项工作将开始缩小这一差距，方法是从喜马拉雅山脉主要河流系统的特征良好的河流样本中生成概念验证数据集，这些样本已经测量了溶解硫酸盐的 34-S 和 18-O 成分。研究人员将对这些样本中溶解的硫酸盐的 17O 成分进行测量，以调查硫酸盐在下游洪泛区的潜在来源和随后的回收利用。河流 17-O-硫酸盐数据集将提供一个严格的框架，用于解释海洋硫酸盐记录中的 17-O 记录。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的评估进行评估，被认为值得支持。影响审查标准。