Mastersize 2000型激光粒度仪分析数据可靠性检验及意义——以洛川剖面S4层古土壤为例

The Reliability and Significance of the Grain-size Obtained by Mastersize 2000 Laser Analyzer:a case study on the typical S4 from Luochuan section

黄土、古土壤剖面中物质粒度是恢复古环境的重要指标之一。精确地测定粒径的大小,是准确而可靠获取气候变化信息的基本前提。通过对洛川典型黄土剖面古土壤S 4及相临黄土层高密度、连续样品多次重复粒度测试结果经统计分析表明:粒径测量的误差主要来自于两方面,即仪器测量与前处理过程,其中前处理过程的影响是粒度测量中误差的主要来源。同时证明,单次测量结果具有不确定性,因此可靠的粒度参数需经多次测量平均获得。但是,此过程会导致某些快速变化信息的丢失和因峰态的平滑而造成粒度变化所反映的变化幅度弱化。

The grain size of loess and paleosol sequence is regarded as one of the most important proxies to reconstruct paleoenvironment. To obtain the reliable information of climate changes, it is necessary to measure the grain size accurately. Using Mastersize2000 Laser Grain-size Analyzer, grain size of loess-palaeosol samples taken from the typical S4 soil section of Luochuan is studied through multi-preparing processes. The results show that the error of grain size measurement originates from two kinds of aspects ： measurement accuracy of the machine itself and samples pretreatment processes. On the experiment, pretreatment of samples is the primary influence factor. At the same time, it was found that credible data are not obtained only through one time measurement, but more time measurements are necessary, and the average result can be used as climate proxy. But this method may made the information of rapid climate changes lost, and made changing range of the grain size inconspicuous which is affected by smoothness of the wave crest shape.