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洞穴石笋碳酸钙 (盐 )δ13C的同位素记录表明 ,其与δ18O同位素记录一样 ,均能反映气候环境的冷暖旋回变化 ,也具有急速的突变事件记录。本文利用近期或古老的洞穴石笋碳酸钙 (盐 )δ13C的同位素组成 ,对桂林地区 4 4ka以来的大气CO2浓度进行了尝试性的估算 ,估算结果表明 ,它可与近期所测量的以及冰岩芯气泡组分分析和北方黄土碳酸盐δ13C估算的大气CO2 浓度值基本接近 ,可以进行相互对比 ,说明利用洞穴石笋碳酸盐δ13C同位素组成对大气CO2 浓度进行估算的方法是可行的。研究表明 ,洞穴石笋碳酸盐δ13C同位素的记录 ,对地质时期的冷事件具有独特的敏感性 ,特别是对新仙女木冷事件和北大西洋Heinrich的H1至H5冷事件反映较为明显 ,在干冷期δ13C同位素快速升高 ,总体上与大气CO2 浓度的变化呈反比 ,大气CO2 浓度的变化与全球性的气候波动大体一致 ,但存在明显的区域性变化特征。
The isotope records of δ13C in the cave stalagmite indicate that the δ13C isotope records reflect the climatic and warm cycles of the climatic environment as well as the abrupt event records. In this paper, we use the isotopic composition of calcium carbonate (salt) δ13C in recent or ancient cave stalagmites to tentatively estimate the atmospheric CO 2 concentration in the region since 4 4 ka in Guilin. The estimation results show that it can be used in combination with the recent measurements of ice cores The results of bubble component analysis and atmospheric carbon dioxide (δ13C) estimated by δ13C in North China are close to each other and can be compared with each other. It is feasible to estimate the atmospheric CO2 concentration using the δ13C isotopic composition of carbonates in caves. The results show that δ13C isotope records of carbonate stalagmites have unique sensitivity to cold events in geologic period, especially for the H1-H5 cold events of the new fairy woody and Heinrich of the North Atlantic, The δ13C isotopes increased rapidly, which was generally inversely proportional to the change of atmospheric CO2 concentration. The change of atmospheric CO2 concentration was generally consistent with the global climate fluctuations, but there were obvious regional variations.