激光粒度仪法与湿筛-沉降法测定火山碎屑物发育土壤颗粒组成的比较

Comparison of Particle Composition of Soil Developed from Pyroclastic Material Measured by Laser Particle Size Analyzer and Wet Sieve-Sedimentation Method

为了比较湿筛-沉降法和激光粒度仪法测定玄武质火山碎屑物发育土壤的颗粒组成的结果,对供试土壤进行了比重值测定,并采用实测比重值和常用比重值(2.65)分别进行了湿筛-沉降法的土壤颗粒组成测定,同时又对样品进行了激光粒度仪法测定。结果表明:玄武质火山碎屑物发育土壤的比重值较土壤的常用比重值有一定的差异,进而导致了两种比重值条件下湿筛-沉降法测定的土壤颗粒组成的差异,但相差不大。激光粒度仪法测定的土壤颗粒组成与湿筛-沉降法比较,黏粒含量偏低,粉粒含量偏高,绝大多数砂粒含量偏高。导致这种差异的原因之一是两种方法的测定原理不同,分别测定的是同一颗粒的不同特征;其次是测定的粒径范围不同,湿筛-沉降法测定<2 mm的全部土粒,但激光粒度仪法对小于某粒径(MS3000激光粒度仪的测量范围是0.01~3500μm)的土粒不做测量;此外,还受黏土矿物的层状构造及土壤分散方法的影响。由于不同生产厂家、不同型号的激光粒度仪,其测量范围不同,对土壤颗粒组成的测定结果会产生一定的影响。所以,建议在应用激光粒度仪测定土壤颗粒组成时,标示仪器的生产厂家和型号。

In order to compare the results of wet sieve-sedimentation method and laser particle size analyzer in the determination of particle composition of basaltic volcanic debris-developed soils,the specific gravity values of the tested soils were determined,and the measured specific gravity values and the commonly used specific gravity values(2.65 g cm^-3)were used to determine the soil particle composition by wet sieve-sedimentation method respectively.At the same time,the samples were determined by laser particle size analyzer.The results show that the ratio of basaltic volcanic clastic material to developed soil is different from that of common soil,which leads to the difference of soil particle composition measured by wet sieve-sedimentation method under two specific gravity conditions,but the difference is not significant.Compared with the wet sieve-sedimentation method,the content of clay is lower,the content of silt is higher and the content of most sand is higher.One of the reasons for this difference is that the measuring principles of the two methods are different,and the different characteristics of the same particle are determined separately;secondly,the range of particle size determined is different.The wet sieve-sedimentation method is used to determine all soil particles<2 mm,but the laser particle sizer method is not used to measure soil particles smaller than a certain particle size(the measuring range of MS3000 Laser Particle Sizer is 0.01-3500μm);moreover,it is also subject to clay.The layered structure of soil minerals and the influence of soil dispersion methods.Due to different manufacturers and different models of laser particle size analyzer,the measurement range is different,which will have a certain impact on the determination results of soil particle composition.Therefore,it is suggested that the manufacturer and model of the instrument should be marked when the laser particle size analyzer is used to determine the composition of soil particles.