A Study of the Abundance of the Atmospheric O2 Mole Fractionin Relationship to the Carbon Cycle and Air-Sea Exchange

在生物地球化学中，几乎没有一个学科比大气中氧气的变化更基础，但人们却知之甚少。氧气是全球生命周期的基本要素，并因燃烧化石燃料和砍伐森林而消耗；然而，必须反映这些过程的大气中氧浓度的变化却从未被探测到。困难仅仅在于没有合适的技术来测量空气中大量氧气背景下预期的氧气变化。直接测量氧的变化将大大改善研究全球碳循环和人类活动引起的扰动的框架。具体地说，测量假定的长期氧气下降率将为确定全球年氧化净值提供一个基础，从而可以为化石燃料燃烧和生物圈氧化产生的碳的净源和净汇构建准确的数字。这将为预测未来二氧化碳水平和未来气候所需的海洋二氧化碳吸收模式提供客观约束。它还将为理解当前二氧化碳水平升高是否正在刺激全球净初级产量提供更好的基础。该项目旨在调查从世界各地的一系列站点收集的空气样本中的大气氧气和二氧化碳含量。这些测量的目的是将大气二氧化碳的季节、纬度和长期趋势与氧气的变化联系起来。这些数据将提供对全球生物量以及海洋和陆地生物生产力变化的见解。空气样品将在玻璃烧瓶和氧气摩尔分数将参考压缩空气标准，使用最新开发的干涉式氧分析仪。测量将伴随着对玻璃烧瓶和高压钢瓶中氧气稳定性的系统研究。其他工作将包括从平流层获得低温提取的空气样本进行氧分析的实验室可行性研究，这将对确定最近的氧气消耗感兴趣。

There is scarcely a subject in biogeochemistry which is more fundamental, yet so poorly understood, as the variability in atmospheric oxygen. Oxygen is an essential element to global life cycles and is consumed by fossil fuel-burning and deforestation; yet the changes in the atmospheric oxygen concentration which must reflect these processes have never been detected. The difficulty is simply that the appropriate technology has not been available for measuring the expected variations in oxygen against the large oxygen background of air. Direct measurements of changes in oxygen would substantially improve the framework for studying the global carbon cycle and the perturbations due to human activities. Specifically, measuring the presumed long term rate of decline in oxygen would provide a basis for establishing the net annual global oxidation from which one could construct accurate figures for the net sources and sinks of carbon from fossil fuel burning and biospheric oxidation. This would provide objective constraints on models of oceanic carbon dioxide uptake which are needed to forecast future carbon dioxide levels and future climate. It would also provide a better basis for understanding whether today's elevated carbon dioxide levels are stimulating global net primary production. This project is designed to investigate the atmospheric oxygen and carbon dioxide fraction in air samples gathered from a series of stations around the world. The purpose of those measurements is to correlate seasonal, latitudinal and secular trends in atmospheric carbon dioxide with variations in oxygen. These data will provide insights into changes in global biomass, and in ocean and land biological productivities. Air samples will be taken in glass flasks and oxygen mole fraction will be referenced to compressed air standards using a recently developed interferometric oxygen analyzer. The measurements will be accompanied by systematic studies of oxygen stability in glass flasks and high pressure cylinders. Other work will include a laboratory feasibility study of obtaining cryogenically extracted air samples from the stratosphere for oxygen analysis, which would be of interest for determining recent oxygen depletion.