岩溶洞穴次生碳酸盐沉积铀及其同位素组成古气候环境研究进展

Progress in the study of paleoclimate reconstruction from speleothem uranium and its isotope

洞穴沉积铀含量及其同位素初始^(234)U/^(238)U[(^(234)U/^(238)U)_0)]变化均与过去气候环境变化关系密切。文章分别对石笋中U含量和(^(234)U/^(238)U)_0,的气候意义进行统计分析发现,多数研究认为洞穴沉积U含量和(^(234)U/^(238)U)_0可能指示土壤湿度和有效降水变化。然而,不管是对洞穴沉积的U含量还是(^(234)U/^(238)U)_0,其气候环境意义解读还存在两种观点。但无论如何,这些研究成果都显示了洞穴沉积的U含量和(^(234)U/^(238)U)_0是研究过去气候环境变化的重要替代指标。在未来的研究中,除了土壤环境和过程,还应关注U来源的相对贡献变化和其他微量元素与U元素的关系。这一指标可能在对东亚地区的大气粉尘活动和冬季风演化、地表生物量的变化研究等方面发挥重要作用。

Uranium content and its isotope initial ^234U/^238U[^234U/^238U）0]preserved in speleothems have a considerable potential to record the changes of the paleoclimate and paleoenvironment. Here we review the studies on these elements and their climate implications. Most previous work suggested that the uranium concentration and （^234U/^238U）0 could indicate the changes of the soil humidity and effective precipitation. However, some researchers hold different viewpoints on this subject. Nevertheless, all these researches agree that U concentration and its isotope should be important alternative indexes for reconstructing paleoclimate and pateoenvironment. In the future, in addition to soil environments and processes, the investigations should be focused on relative contribution of different sources of U and the relationship between U and other trace elementals, which may play an important role in the study of atmospheric dust activity, winter monsoon variations, changes of biomass on the surface, and so on in East Asia.