Fingerprinting and Calibrating Low Oxygen Conditions Using Vanadium Isotopes

使用钒同位素进行指纹识别和校准低氧条件

• 批准号: 1434785
• 负责人: Jeremy Owens
• 金额: $ 36.95万
• 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: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434785&HistoricalAwards=false
• 关键词: Fingerprinting; Calibrating; Low; Oxygen; Conditions

Discovering, testing, and developing chemical proxies (relic materials) in marine sediments that reveal how strongly or weakly oxidizing near-surface environmental conditions were in the Earth's geological past are immensely important for understanding interactions between ocean chemistry, biological evolution and extinctions, and climate. To date scientists do not have a proxy for low but non-zero oxygen conditions -- the sort of conditions that are likely to have dominated in biologically important periods of Earth history. In this project, researchers will study the relationship between bottom water oxygen concentration and the isotopes of the trace metal vanadium (V) in a range of oxygen conditions in the modern ocean. Based on pilot data, theoretical calculations and dissolved seawater V concentrations they believe that stable V isotope ratios of core top sediments will correlate systematically over a range of bottom water oxygen conditions. By analyzing these materials, the research team expects to establish the relationship between V isotopes and bottom water oxygen concentrations. Given the importance of chemical proxies to quantify past climate change, the results of this study will be of great importance to the modern and paleoceanographic community, as well as for modelers to better understand a broad range of oxygen variability in Earth history.Although recent investigations have provided a wealth of information about the redox conditions of the ancient oceans, there is a significant gap in understanding low oxygen conditions throughout Earth history. Therefore, it is important to develop new paleoredox proxies that can provide additional and complementary knowledge about ocean redox conditions during these important periods of Earth history. In this study, scientists will analyze bulk sediments and their organic and ferromanganese mineral fractions to investigate the V isotopic variability within the various sedimentary components. (These samples comprise organic rich to ferromanganese rich sediments due to a range in bottom water oxygen concentrations.) Reconstructing marine low oxygen conditions using vanadium isotopes would fill a void in the paleoredox proxy toolbox. Developing, calibrating, and fingerprinting the V isotopic variability in modern sediments is required to be able to apply vanadium isotopes as an accurate paleoredox proxy.

在海洋沉积物中发现、测试和开发化学代理（遗迹材料），揭示地球地质历史中近地表环境条件氧化的强弱程度，对于理解海洋化学、生物进化和灭绝以及气候之间的相互作用非常重要。迄今为止，科学家们还没有找到低但非零氧条件的替代指标，这种条件可能在地球历史上具有重要生物学意义的时期占据主导地位。 在该项目中，研究人员将研究现代海洋各种氧气条件下底层水氧浓度与微量金属钒（V）同位素之间的关系。 根据试验数据、理论计算和溶解海水 V 浓度，他们认为岩心顶部沉积物的稳定 V 同位素比率将在一系列底层水氧条件下系统地相关。 通过分析这些材料，研究小组希望建立V同位素与底层水氧浓度之间的关系。 鉴于化学替代物对量化过去气候变化的重要性，这项研究的结果对于现代和古海洋学界以及建模者更好地了解地球历史中广泛的氧变化具有非常重要的意义。尽管已经提供了有关古代海洋氧化还原条件的大量信息，但在了解整个地球历史上的低氧条件方面存在着巨大的差距。因此，开发新的古氧化还原代理非常重要，它可以提供有关地球历史这些重要时期海洋氧化还原条件的额外和补充知识。 在这项研究中，科学家将分析大块沉积物及其有机和铁锰矿物成分，以研究各种沉积成分内的 V 同位素变异性。 （由于底层水氧浓度范围不同，这些样品包含富含有机物到富含铁锰的沉积物。）使用钒同位素重建海洋低氧条件将填补古氧化还原代理工具箱中的空白。 需要对现代沉积物中的 V 同位素变异性进行开发、校准和指纹识别，以便能够应用钒同位素作为准确的古氧化还原替代物。