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Cosomogenic isotope production and global carbon cycles during the past 10,000 years

过去一万年的同位素产生和全球碳循环

基本信息

批准号：
13490013
负责人：
KITAGAWA Hiroyuki
金额：
$ 7.81万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

The cosinogenic radionuclide ^<14>C is produced in the Earth's atmosphere mainly by the interaction of cosmic rays with nitrogen. Since the cosmic ray flux is modulated by geo-and heliomagnetic shieldings, records of ^<14>C provide information on variations in the solar activity and the geomagnetic field intensity in the past, After oxidation to ^<14>CO_2 (radiocarbon) becomes a constituent of the global carbon cycle, and exchanges between atmosphere, biosphere and the ocean. The analysis of the past atmospheric ^<14>C concentration therefore provides the possibility to detect change of global carbon cycle. However, since the atmospheric ^<14>CO_2 concentration is sensitive to changes in the ^<14>C production rate, we need to verify the past production rate from the independent data. In this study, we focused on a cosmogenic radionuclide, ^<10>Be, as a trace of.pastproduction changes.In this study, we aimed to investigate the past carbon cycle by the comparison of ^<14>C concentration with ^<10>Be abundance. In general, the past ^<10>Be reconstructions have carried out from ice core analyses. We had an approach to reconstruct the ^<10>Be change from the terrestrial deposition such as lake sediment and peat depositions with higher sedimentation rate. As research marches on 10Be analysis of the lake sediments, it became very obvious that the ^<10>Be concentration of the lake sediments can be strongly influenced by the ^<10>Be cycle on the earth's surface ; supply of the material form atmosphere and river. Based on the this fact, we here complete following interpretation into a report ; developed method of ^<10>Be concentration of the terrestrial sediments, extended wiggle matching method to determine the sedimentation rate, ^<10>Be on the earth's surface based on the analysis of a core from the lake Biwa.

宇宙放射性核素^C主要由宇宙射线与氮的相互作用在地球大气中产生。<14>由于宇宙线通量受地磁和日磁屏蔽的调制，^C的记录提供了过去太阳活动和地磁场强度变化的信息。氧化成^CO_2（放射性碳）后，成为全球碳循环的组成部分，并在大气、生物圈和海洋之间进行交换。<14><14>因此，对过去大气^C浓度的分析提供了检测全球碳循环变化的可能性。<14>然而，由于大气中的^CO_2浓度对^C产生率的变化很敏感，我们需要从独立的数据中验证过去的产生率。<14><14>在这项研究中，我们专注于宇宙成因放射性核素^Be，作为过去生产变化的痕迹，在这项研究中，我们的目的是通过比较^C浓度和^Be丰度来研究过去的碳循环。<10><14><10>一般来说，过去的重建是根据冰芯分析进行的。<10>我们有一种方法来重建陆地沉积（例如湖泊沉积物和沉积速率较高的泥炭沉积）的^Be变化。<10>随着对湖泊沉积物~（10）Be分析研究的深入，湖泊沉积物中~（10）Be的含量明显受到地表~（10）Be循环、大气和河流物质供给的影响。<10><10>基于这一事实，我们在此完成了以下解释报告：开发了陆地沉积物中^Be浓度的方法，扩展了摆动匹配法来确定沉积速率，根据对琵琶湖岩心的分析，^Be在地球表面上。<10><10>