乌鲁木齐城市土壤粒度特征分析

Characteristics of Soil Particle Size in the Urumqi City

土壤粒度组成是土壤重要的物理特性之一,对提高绿洲城市土壤抗风蚀能力、持水能力和土壤养分等有重要意义。研究选用乌鲁木齐城市不同区域的45个表土样品,利用激光衍射粒度仪和扫描电镜分析土壤粒度特征。结果表明:1)研究区表层土壤颗粒中砂粒含量偏低,粉粒含量最大,不同采样区同粒级间含量差异性不大。2)研究区土壤颗粒总体较细,分选性差,偏度为正偏态近对称型,峰度为中等窄峰态。粒度参数的空间分布规律为城南平均粒径高于城北,分选系数与平均粒径变化趋势类似,样品多为正偏,建设用地土样的偏度值从北部到南部呈下降趋势,多数样地峰态值偏高。3)研究区土壤粒度频率分布曲线由近似正态分布的单峰和非正态分布的多峰构成,其中农用地样品为单峰曲线,表明沉积物存在单成因组分,而建设用地和未利用地为多峰,说明存在多成因组分。同时发现典型样点的电镜图与粒级含量分布结果具有相似性和一致性。

The particle size distribution is one of the important physical properties of the soil. It is of great sig- nificance to improve soil anti-wind erosion, water retention and nutrients, etc. , for oasis city. In this paper, forty-five soil samples were collected from different regions of Urumqi and analyzed by laser diffraction parti- cle size analyzer and scanning electron microscope to exhibit their soil particle size features. The results are as follows. 1） The particles of topsoil in the study area are composed of a lower sand content and higher silt content. There is no significant difference of contents among the same content levels of different sampling re- gions. 2） The particles of the soil are fine and low sorting. The distribution is a type of nearly symmetric positive skewness and moderate narrow kurosis. Moreover, the mean particle size of the south of the city is higher than that of the north of the city. Sorting coefficient and the mean particle size present the similar trend and the samples are a type of positive skewness. The skewness shows a decreasing trend from the con- struction land in the north to the south and the majority of the sampling soil has a higher kurtosis values. 3） The curves of soil particle size frequency distribution present the normal unimodal and multimodal non-nor- mal distributions. The curves of particle frequency distribution in agricultural lands show a single peak, indi- cating that the sediment is mainly caused by a component. However, the curves of construction land and un- used land show the multiple peaks, indicating the existence of multiple components from different sources. In addition, the result of typical samples analyzed by the scanning electron microscope is similar and consistent with the distribution of content levels.