湖泊沉积物硅藻提纯方法

硅藻是湖泊沉积物的重要组成部分,沉积物硅藻硅氧同位素在重建古气候、古环境方面具有重要价值。从湖泊沉积物中分离出高纯度硅藻样品十分困难,目前已有的硅藻提纯方法大多要求沉积物硅藻含量高于20%,其适用范围受到很大限制。本文通过对各种分离提纯过程的反复实验和镜下观察对比分析,建立了一套有效的五阶段硅藻提纯方法(盐酸和双氧水除碳酸盐与有机质-过筛除粗颗粒碎屑-沉降除粘土-重液浮选纯化硅藻-过筛除杂),成功地从初始硅藻含量大于7%的沉积物中提取出纯度达90%以上的硅藻样品,为广泛开展沉积物硅藻硅氧同位素研究奠定了基础。在硅藻提纯过程中,通过显微镜下观察对比分析来选择合适的分离方法和流程是建立有效硅藻提纯方法的必要手段。

AN EFFECTIVE CLEANING METHOD FOR PRODUCING PURE DIATOM SAMPLES FROM LAKE SEDIMENTS

As an important component of lake sediments,diatom is of great value for reconstructing paleoclimate and paleoenvironment.However,it is very difficult to get high-purity diatom samples from lake sediments.Nowadays,available clean-up methods work best only for sediments with >20% diatom content,thus its application is very limited.Based on repeated experiments of various cleaning procedures and observation in light microscope,a continuous five-stage cleaning method is established,including organic matter and carbonate removal by HCl-H2O2,coarse detrital minerals removal by sieving,clay removal by differential settling,diatom purification by heavy liquid floatation and impure material removal by sieving.The five-stage cleaning method is successfully used to produce diatom samples with >90 diatom content from lake sediments with >7% diatom content.This new procedure provides a good approach to study the silicon and oxygen isotope in diatom.It is necessary to observe and compare repeatedly the distribution characteristics of diatom and non-diatom materials in sediments via light microscope so as to choose appropriate separation procedure and to establish effective cleaning method.