作　　者： (吴书刚）; (周晓龙）; (程鹏）; (熊晓虎）;

机构地区： 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710061 陕西省加速器质谱技术与应用重点实验室,西安710061

出　　处： 《地球环境学报》 2017年第4期340-346,共7页

摘　　要： 树木年轮是重建过去大气Δ^(14)C变化和开展化石燃料CO_2示踪的重要介质。本文采集重庆金佛山一棵树龄10 a的水杉,通过AMS-^(14)C测量重建了2004—2013年间大气Δ^(14)C的变化,即以平均每年3.9‰的速率下降;发现随着大气CO_2浓度的持续上升,大气中Δ^(14)C不断降低。重庆金佛山树轮Δ^(14)C与Jungfraujoch、Schauinsland本底观测站大气Δ^(14)C值基本一致,表明金佛山树轮Δ^(14)C没有受到当地或区域化石燃料碳排放的影响,可以作为我国该时段内大气Δ^(14)C的本底值,计算化石燃料CO_2的贡献,也为今后研究本底Δ^(14)C的选择提供了新的思路。此外,发现受人类核活动影响地区的Δ^(14)C高于金佛山,而受人类化石燃料排放地区的Δ^(14)C低于金佛山。 Background, aim, and scope Radiocarbon is a cosmogenic radionuclide which kept at a steady state in natural condition. But the atmospheric nuclear test between the late 1950s and early 1960s nearly doubled the amount of 14C. For the safety of nuclear environment, many laboratories began to monitor the atmospheric △14C. Till present, they have obtained long-time series of △14C data. However, there is little work on atmospheric △ 14C in China. As the progressive of carbon cycle study, more and more researchers started to trace fossil fuel CO2 using △14C. A problem is that many researches have no their own △14C environmental background and use that of Europe or America. If this will result in some bias to the fossil fuel CO2 is unknown. In this paper, tree rings of a Metasequoia glyptostroboides growing in Jinfo Mountain, Chongqing was studied to （1） reconstruct the interannual variability of atmospheric △14C during the period of 2004 to 2013; （2） to explore whether the △14C of tree rings growing at remote site can be used as environmental background. This work is very important to the research of fossil fuel CO2 tracing using tree ring △14C and the choice of environmental background. Materials and methods Sampling site （28°59′8＂N, 107° 11′35＂E; 1560 m） is located in the center of Jinfo Mountain scenery, Nanchuan District, Chongqing. This scenery, with an area about 441 km2, has been named as a National Nature Reserve in 2000. The distances of the scenery from Nanchuan city and Chongqing city are 18 km and 88 km respectively, thus far from influences of human activities. In July 2013, a disc with a thickness of about 20 mm was collected using an oil saw. By identifying the sample with tree-ring skeleton diagram, we found that the widths of the rings are wide, ranging from 4.5 to 8.1 mm. The age of the tree was ten years old and there was no pseudo ring or missing ring. The tree rings from outmost to inmost were growing from 2013 to 2004, respectively. Cellulose and lignin, the m

关 键 词： 树轮 化石燃料 环境示踪