Triple Oxygen Isotope Composition of Stratospheric Carbon Dioxide as the Basis for a New Proxy of Marine and Terrestrial Biosphere Productivity

平流层二氧化碳的三重氧同位素组成作为海洋和陆地生物圈生产力新指标的基础

• 批准号: 0096504
• 负责人: Kristie Boering
• 金额: $ 28.51万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-15 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0096504&HistoricalAwards=false
• 关键词: Triple; Oxygen; Isotope; Composition; Stratospheric

Anomalies in the oxygen isotope compositions of carbon dioxide (CO2) and molecular oxygen (O2), which are the basis for new probes of gross carbon exchanges between the atmosphere, biosphere, and oceans, will be investigated. These anomalies are the results of stratospheric reactions involving O2, ozone (O3), oxygen atoms, and CO2. The rates for O3 formation from the reaction O+O2 are different for different isotopic species. The resulting anomaly in O3 is then photochemically transferred to CO2, although other reactions to be studied might also contribute. Anomalies in CO2 are accompanied by corresponding anomalies in O2 (from which the O3 formed). This isotopic signature is destroyed only by respiration/photosynthesis processes at the Earth's surface. Once the stratospheric anomalies are better quantified, the isotopic composition of O2 in the troposphere can therefore be used to infer globally averaged marine and terrestrial biosphere productivity. Ice-core records of the O2 isotopic composition can then be used to derive the biospheric productivity and its response to environmental change for the past 400,000 years. This will lead to a better understanding of Earth's climate history, and therefore, future.In this project, stratospheric air samples will be analyzed for the isotopic composition of CO2 using isotope ratio mass spectrometry. Coupled with laboratory experiments and modeling, these measurements will provide new observation-based constraints on the mechanisms that lead to the observed compositions and on the fluxes of stratospheric CO2 and O2 to the troposphere. This information is needed to interpret the O2 record.

二氧化碳（CO2）和分子氧（O2）的氧同位素组成异常将被研究，这是大气、生物圈和海洋之间总碳交换新探测的基础。这些异常现象是涉及 O2、臭氧 (O3)、氧原子和 CO2 的平流层反应的结果。对于不同的同位素种类，O+O2 反应形成 O3 的速率不同。由此产生的 O3 异常现象随后通过光化学作用转移为 CO2，尽管其他待研究的反应也可能有所贡献。 CO2 的异常伴随着 O2（O3 的形成）的相应异常。这种同位素特征仅通过地球表面的呼吸/光合作用过程而被破坏。一旦平流层异常得到更好的量化，对流层中氧气的同位素组成就可以用来推断全球平均海洋和陆地生物圈生产力。 O2 同位素组成的冰芯记录可用于推导过去 40 万年的生物圈生产力及其对环境变化的响应。这将有助于更好地了解地球的气候历史，从而更好地了解未来。在该项目中，将使用同位素比质谱法分析平流层空气样本中二氧化碳的同位素组成。与实验室实验和建模相结合，这些测量将为产生观测到的成分的机制以及平流层二氧化碳和氧气流向对流层的通量提供新的基于观测的约束。需要此信息来解释 O2 记录。