黄土花粉分析的筛析—重液综合法

INTEGRATIVE METHOD OF SIEVING AND HEAVY LIQUID IN POLLEN ANALYSIS OF LOESS—Data Analysis and Processing

高分辨黄土花粉研究可以揭示黄土高原植被演变规律,探讨古气候、古生态格局,提供人类活动及其环境效应信息。筛析-重液综合法以黄土花粉筛析法和重液法的实践为基础,是为满足高分辨率黄土花粉研究需要的新方法。该方法主要使用花粉筛析分析器过滤细粒物质,减轻30%的样品量,减少粘土等细粒物质的粘滞和吸附作用;采用不同类型重液分阶段提取花粉,增强花粉收集率,提高花粉的清晰度。与已有的黄土花粉分析法相比具有以下优点:(1)花粉获取率高,丢失少,花粉种类多,信息量丰富;(2)花粉底样清洁,花粉易鉴定;(3)样品需求量适中,分析流程短;(4)不使用有毒化学药品且分析成本低。

High - resolution pollen study of loess can reconstruct the vegetation history in loess plateau and discuss the vegetation characteristics of terrain and non- terrain in different episode. In the meantime, high-resolution pollen records play an important role in further studying on the rule of vegetation variation and palaeoecological pattern, understanding the control factors and dynamic mechanism of monsoon variation, providing the information of human activity and its impaction to environment in loess plateau. The Integrative method of sieving and heavy liquid provides a new approach for the studying on the analysis of loess pollen. The method is also applied to the samples of culture layer, soil and the lake sediment. The sieving analysis machine is used to take out the fine particles with sieve （the aperture〈 10μm）. In this process, not only is about 30 % weight of sample removed, but also the porosity of sample is increased, the viscosity and adsorption of clay are reduced. On the other hand, two kinds of heavy liquid are used in two different steps for the purpose of increasing the rate of pollen extraction and decreasing the costing of expensive chemical reagent. The pollen results of 19 samples from Fufeng section show that a total of 41 pollen taxa including Abies （ the biggest grain size） and castanea （the smallest grain size） are obtained, which cover the main pollen types of loess plateau. The method helps us to get over 300 pollen grains only counting 2 - 3 slides. Comparing with the conventional method of pollen analysis, the advantages of sieving- heavy liquid method are as follows： （1） Little pollen is loss and more pollen types. （2） Less destroying to the pollen structure and lines. （3） Shorter process. A whole process of 8 samples only needs 4 days. （4） Not using the toxicity reagent for the safety of the analysis process.