环青海湖表层土壤沉积物粒度分布特征及其指示意义

Grain Size Distributions of the Surface Soil Deposit Around Qinghai Lake and Its Implications

对环青海湖区38个表层土壤沉积物样品进行了粒度特征分布分析,结果表明：环青海湖表层土壤沉积物粒度组成以粉砂为主,占所有采样点土壤粒度组成的52%,砂含量次之,占37%,黏粒含量最少,占11%;环湖区38个采样点主要植被类型下表层土壤粒度百分比中也表现出粉砂〉砂〉黏粒;环青海湖区表层土壤沉积物粒度特征表明青海湖以东表层土壤沉积物粒度特征呈单峰模式、以西表层土壤沉积物粒度特征呈不对称双峰模式、以南表层土壤沉积物粒度特征近乎正态分布、以北表层土壤沉积物粒度特征呈多峰模式;环青海湖区表层土壤沉积物的平均粒径为1.96~6.71Ф,平均值为4.68Ф,为粉砂粒级;峰态值为0.75〈KG〈1.89,平均值为1.09;标准离差变化范围为0.81~2.63,平均值为1.77;偏度变化范围为-0.03~0.43,平均值为0.14。分析结果说明环青海湖区湖东区域为典型的风成砂沉积、湖西和湖南区域表层土壤沉积为风成黄土、湖北表层土壤沉积环境复杂多样。

The research of analyzing the particle size feature distribution of 38 surface soil deposit samples col lected from the areas around the Qinghai Lake showed that the main component of the surface soil deposit is silt accounting for 52~ in the composition of soil grain. The sand content is 37%, and is the second largest. And the clay content is 11%, and is the least. The percentage of the particle size of the surface soil which is under the main vegetation types in the 38 sample points which are around the Qinghai Lake presents that silt content is more than sand content, and sand content is more than clay content. The feature of particle size distribution of the surface soil deposit collected from the east of the Qinghai Lake presents unimodal pattern, the west of the Qinghai Lake presents asymmetrical bimodal pattern, it is close to normal distribution in the south of the Qinghai Lake, it presents multimodal pattern in the north of the Qinghai Lake. The average par- ticle size of the surface soil deposits collected around the Qinghai Lake area is between 1. 9646. 710, with an average of 4. 680, which is at the level of silt. The kurtosis values ranges from 0.75 to 1.89 with an average of 1.09. The standard deviation varies from 0.81 to 2.63 with an average of 1.77. And the skewness ranges from --0.03 to 0.43 with an average of 0.14. The analytical results reveal that the east area of Qinghai I.ake is typical eolian sand deposition in the surface soil, it is eolian loess in the west and south of Qinghai Lake, and the soil deposits are complex and diverse in the north of Qinghai Lake.