同步辐射技术在高分辨率古气候、古环境变化中的应用

APPLICATION OF SYNCHROTRON RADIATION TECHNOLOGY IN HIGHRESOLUTION PALEOCLIMATIC AND PALEOENVIRONMENTAL RESEARCH

随着古全球变化研究的深入,理解快速古气候变化的过程及机制正成为学术界关注的关键问题。同步辐射X射线荧光原位无损分析是近年来发展起来的新方法。本文简单介绍了同步辐射技术,指出在分辨率和分析灵敏度方面,同步辐射X射线荧光分析比其他方法更具有优势。以北极斯瓦尔巴德群岛Bolterskardet湖年纹层为例,介绍同步辐射技术在年纹层沉积物中的应用。初步研究结果表明,同步辐射X射线荧光分析数据能够揭示元素含量变化的季节规律。在季节变化层面上,Rb/Sr比值的旋回变化与每个年纹层序列中夏季正粒序层逐渐过度为暗色的冬季粘土微层对应,甚至Rb/Sr比值变化亦能够反映夏季纹层内的次一级波动。因此,沉积物的粒度变化可能是决定Rb/Sr比值季节波动的主要因素。其他元素(As和Ti)含量的变化受沉积物粒度影响较小,Ti含量的变化可能主要受物理风化作用以及区域降水量变化的影响。

To understand the process and dynamics of abrupt climate changes requires high temporal resolution researches on the past proxy records. Synchrotron radiation X-ray fluorescence（SRXRF） method,a newly developed technology in recent years,provides a potential tool for high-resolution,in-situ analyses of elements in sedimentary sequences. The principle and application of SRXRF and its advantages in the research of paleoclimatic and paleoenvironmental history were briefly reviewed in this paper. An annually laminated sediment core recovered from Boherskardet Lake was analyzed for element content with the method of SRXRF. The data indicate that the seasonal cycle of variations in the element content was detected by the SRXRF technology. The Rb/Sr ratio of the sediment core displays covariations with the silt layer formed in summer and clay one formed in winter. Changes in the content of As and Ti are less influenced by the grain size of the sediments. Nevertheless the content of Ti is probably related to the weathering intensity and precipitation in the lake region.