不同预处理对沉积物粒度分析结果的影响

Influence of Different Pretreatments on Size Analysis and Its Implication

粒度分析的方法很多 ,无论是传统的方法还是现代的激光粒度分析法 ,都需要对样品做预处理 .不同的预处理所得到的分析结果不同 .取自东海农场泥质潮滩的 4 1个样品 ,经稍做振荡分散、加少量双氧水与盐酸和加大量双氧水与盐酸等三种截然不同的方法预处理后 ,平均粒径减小 ;中值粒径减小 ;标准偏差增大 ,但不影响沉积物的分选等级 ;粒级含量变化 ,但不影响沉积物的命名 .这些变化一方面是沉积物中颗粒有机质和贝壳、生物碎屑类碳酸盐被双氧水和盐酸除去所致 。

The pretreatment is needed by all grain size analysis methods,including traditional and modern-laser analyses.Different pretreatments lead to different results.In this paper,forty-one surface samples,taken from the Nanhui mudflat fringing the Changjiang Delta,were pretreated in three ways.In method Ⅰ,samples are saturated with water and dispersed by slight shaking.In method Ⅱ ,samples are immersed successively by little hydrogen peroxide and hydrochloric acid.In method Ⅲ,samples are boiled with hydrogen peroxide and hydrochloric acid in order.The results show that,1) the mean and median particle sizes decrease,2) the standard deviation increases but does not affect the grade of sorting,3) changes of grain component are evident but do not influence sample denomination according to components.The variations may be due to removing organic and carbonate grains,such as shell and bioclast,and separation of floccules.