利用树轮中14C研究典型内陆城市大气化石源CO2长期排放量

CO2 is a major greenhouse gas. The main source of atmospheric carbon dioxide concentration is fossil combustion. Determination of the amount of radioactive carbon (14C) in air or plant is an effective way to monitor fossil source emissions. Quantitative assessment of the typical inland urban fossil source CO2 emissions is the project of a scientific and environmental protection value with the increasing population, economic growth and the increasing complexity of atmospheric transmission. Measuring the radioactive carbon in tree wheel of a typical inland urban will provide technical methods and data for the above studies. Based on the small 14C accelerator mass spectrometer developed by China Institute of Atomic Energy, this research project is based on the pine tree rings with age of 20 years or more near the atmospheric CO2 sampling point. The typical inland urban are analyzed for δ13C, △ 14C using tree rings for a long time and the interannual CO2 concentration of atmospheric fossil fuels in the typical inland urban in recent 20 years was calculated by combining the atmospheric interannual CO2 concentrations collected by the Institute of Atmospheric Physics, Chinese Academy of Sciences for nearly 20 years. This study is of great significance to quantitatively evaluate the long-term emission status and energy saving and emission reduction of fossil fuels in China.

CO2是一种主要的温室气体，大气二氧化碳浓度升高的主要来源是化石燃烧。测定空气或植物中放射性碳（14C）含量的变化量是监测化石源排放的有效方法。随着人口、经济的增长和大气传输的日益复杂，量化评估典型内陆城市化石源CO2的长期排放是一个具有科学意义和环境保护价值的项目。测量典型内陆城市树轮中的放射性碳将可以为上述研究提供技术方法和数据。本研究项目拟以中国原子能科学研究院自主研发的小型14C加速器质谱为基础，以大气CO2采样点附近树龄20年以上的松树年轮为样品，解析典型内陆城市近20年树轮中δ13C，△14C长时间的变化特征，并结合中科院大气物理研究所采集的近20年的大气年际CO2浓度，计算典型内陆城市近20年的大气化石源年际CO2排放量。此研究对量化评估我国目前化石源CO2的长期排放状况和节能减排效果具有重要意义。

研究化石燃料产生的二氧化碳对了解城市碳排放具有重要的意义，有助于我们制定减排策略。通过对北京北四环附近大气物理所内雪松树轮样品进行制备，利用加速器质谱对样品中14C进行测量，分析和研究北京城市化过程中大气化石源排放的变化趋势。结果显示：样品中14C浓度有降低的趋势，与经济社会发展中燃烧的大量化石燃料有正相关性。因为燃烧大量不含14C的化石燃料，排放CO2，稀释了大气中的CO2浓度。本项目为后续深入研究14C在环境中的示踪应用奠定基础。