Carbonate contents of lake sediments determined by XRD method

Abstract

湖泊沉积中的碳酸盐对于气候环境具有很好的指示意义.利用化学分析方法(气量法)和X衍射(XRD)方法,对青藏高原可可西里库赛湖KS-2006孔沉积物中的碳酸盐含量进行了半定量分析.结果表明:虽然KS-2006孔沉积物中的矿物种类达9种之多,且XRD的测量误差(±5%)高于气量法的测量误差(±0.8%);但XRD法获得的KS-2006孔沉积物碳酸盐总含量的平均值(18.9%)以及波动范围(7%~39%),同气量法所获得的碳酸盐含量的平均值(19.4%)和波动范围(5.0%~30.7%)基本一致,而且二者具有很好的正相关关系(相关系数R²为0.3940),随深度的波动趋势一致,说明XRD方法在半定量分析湖泊沉积物碳酸盐矿物种类及其含量方面,具有很高的可靠性.;Carbonate in lake sediments has an indicative significance for climate and environment. In this paper, the carbonate contents were semi-quantitatively analyzed by meaning of chemical analysis(gasometric method) and X-ray diffraction(XRD method), which were from the sediments of the core KS-2006 of Lake Kusai in Hoh Xil region, Qinghai-Tibetan Plateau. The results showed that there were at least nine kinds of minerals in the core KS-2006, and the measurement error of XRD method(± 5%) was higher than that of gasometric method(± 0.8%). However, the XRD method obtained the average value(18.9%) and variation range(7%-39%) of the total carbonate contents from the sediments of the core KS-2006, which was basically identical with the average value(19.4%) and variation range(5.0%-30.7%) comparing with both of the result. Meanwhile, it showed a positive correlation between the XRD method and gasometric method, and fluctuation tendency with the depth was uniform. This indicated that the XRD method was a reliable method which can be well used to semi-quantitatively analyze the kinds of carbonate minerals and determine their content in lake sediments.