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首页> 外文学位 >Advancing the use of radiocarbon in studies of global and regional carbon cycling with high precision measurements of carbon-14 in carbon dioxide from the Scripps Carbon Dioxide Program.
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Advancing the use of radiocarbon in studies of global and regional carbon cycling with high precision measurements of carbon-14 in carbon dioxide from the Scripps Carbon Dioxide Program.

机译：通过Scripps二氧化碳计划对二氧化碳中的碳14进行高精度测量，从而促进在全球和区域碳循环研究中使用放射性碳。

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摘要

Measurements of 14C in atmospheric CO2 have served as a powerful geochemical tracer since the first observation programs began over 50 years ago. As the nuclear weapons tests of the 1950s and 60s caused an enormous perturbation to natural atmospheric 14C levels, tracking the response of 14C in CO2 provided a measure of exchange rates between different regions of the atmosphere and between the troposphere and the ocean surface and terrestrial biosphere. Early measurements of 14C/12C, or Delta14 C, in tree rings provided clear evidence that rising CO2 concentrations were due to human activities by revealing the dilution of 14C in the atmosphere by the combustion of million year old fossil carbon, a process termed the "Suess Effect".; This thesis aimed to continue and expand the use of Delta14 C in atmospheric CO2 for investigating carbon cycle dynamics. Since much of the excess 14C derived from nuclear weapons testing has been redistributed into oceanic and biospheric reservoirs, trends and gradients in Delta14C of CO2 have diminished to levels that are nearly commensurate with measurement precision at most laboratories. Development of improved methods for Delta14C analysis by accelerator mass spectrometry at Lawrence Livermore National Laboratory advanced measurement uncertainty to 1.7‰.; Application of the improved analytical procedures to an archive of CO 2 samples from the Scripps CO2 Program produced 2-15 year monthly time series of Delta14C at seven global sampling stations. The high precision observations show variability in the secular trend of Delta14C that could enable new insights to the climatic influences on CO2 exchange. Measurement of a shift in the Delta 14C gradient between the Northern and Southern Hemispheres since the 1980s also places constraints on regional fluxes of carbon, with particular relevance to Southern Ocean dynamics. The measurements presented here contribute significantly to the amount and global coverage of recent Delta14 C observations available to the community.; The thesis also demonstrates the application of Delta14C measurements for identifying fossil fuel-derived CO2 in vertical profiles sampled by aircraft. Similar measurements could be used to distinguish regional sources of industrial or biospheric CO2 or to investigate the mixing of surface CO2 fluxes in the troposphere.
机译：自从50多年前开始实施第一个观测计划以来，大气CO2中14 C的测量就一直是一种强大的地球化学示踪剂。由于1950年代和60年代的核武器试验对自然大气14C浓度产生了极大的干扰，因此跟踪14 C在二氧化碳中的响应提供了对大气不同区域之间以及对流层与海洋表面以及陆地生物圈之间交换速率的一种度量。 。通过对树木年轮中14C / 12C或Delta14 C的早期测量，可以清楚地证明二氧化碳浓度的升高是由于人类活动造成的，它揭示了燃烧一百万年前的化石碳在大气中对14C的稀释作用，这一过程称为“ Suess效应”。本论文旨在继续和扩展在大气CO2中使用Delta14 C来研究碳循环动力学。由于大部分来自核武器试验的过量14C已重新分配到海洋和生物圈储层中，因此大多数实验室中，CO2 Delta14C的趋势和梯度已减少到几乎与测量精度相当的水平。劳伦斯·利弗莫尔国家实验室的加速器质谱分析开发了改进的Delta14C分析方法，将测量不确定度提高到1.7‰。将改进的分析程序应用到Scripps CO2计划的CO 2样品档案中，在七个全球采样站产生了Delta14C每月2-15年的时间序列。高精度观测表明Delta14C长期趋势的变化，这可能为气候对CO2交换的影响提供新的见解。自1980年代以来，对北半球和南半球之间Delta 14C梯度变化的测量也限制了碳的区域通量，特别是与南大洋动力学有关。这里介绍的测量结果对社区可获得的最新Delta14 C观测值的数量和全球覆盖率做出了重大贡献。本文还演示了Delta14C测量在识别飞机采样的垂直剖面中化石燃料衍生的CO2中的应用。类似的测量可用于区分工业或生物圈CO2的区域来源或研究对流层表面CO2通量的混合。

著录项

  • 作者

    Graven, Heather Dawn.;

  • 作者单位

    University of California, San Diego.$bOceanography.;

  • 授予单位 University of California, San Diego.$bOceanography.;
  • 学科 Biogeochemistry.; Atmospheric Sciences.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 274 p.
  • 总页数 274
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物地球化学、气体地球化学;
  • 关键词

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