宁夏黄河以东固定沙丘土壤粒度特征及小尺度空间分异

Soil Grain Size Characteristics and Small Scale Spatial Differentiation of Fixed Dune in East of the Yellow River in Ningxia

为探明固定沙丘粒度特征及小尺度空间差异,以宁夏河东沙区典型固定沙丘作为研究对象,通过网格法布点采样,分析研究该区域土壤粒度特征。结果表明:研究区颗粒组成以中沙和细沙为主。不同地貌部位的颗粒组成不同,丘间地、背风坡、迎风坡部位的粉沙体积分数、极细沙体积分数依次减小,细沙体积分数依次增加,背风坡的中沙、粗沙体积分数高于迎风坡。丘间地、背风坡、迎风坡的粒度分布曲线形态相似,均在主峰处差距最大。在粒径小于200μm时,丘间地的体积分数累积量高于背风坡、迎风坡的累积量,且细沙、中沙的累积量最多,曲线斜率最大。研究区风沙土的平均粒径在(2.04~2.10)Φ,分选性为中等及较好,土壤颗粒的偏态属于近对称分布,峰度曲线分布为中等状态。平均粒径与标准偏差、偏度、峰度之间存在一定的相关性,且不同地貌部位相关性存在差异。丘间地平均粒径与标准偏差、偏度呈正相关,与峰度呈负相关;背风坡平均粒径与标准偏差、偏度、峰度都呈正相关但相关系数匀较小,迎风坡的参数相关性最不显著。

In order to explore the grain size characteristics and small-scale spatial differentiation of fixed dune,we selected the typical fixed dune in the sand land in the east of the Yellow River in Ningxia as the research object,and the soil grain size characteristics in this region were analyzed.The grain composition of the study area was mainly medium sand and fine sand.The grain composition of different geomorphic parts was different.The content of silt and very fine sand in the site between sand dune,leeward slope and windward slope decreased stepwise,while the content of fine sand e increased stepwise.The content of medium sand and coarse sand in leeward slope was higher than that in windward slope.The grain size distribution curves of the site between sand dune,leeward slope and windward slope were similar,and the difference was the largest at the main peak.When the grain size was less than 200μm,the volume percentage accumulation of the site among sand dune land was higher than that of leeward slope and windward slope,and the accumulations of fine sand and medium sand were the largest,and the slope of curve was the largest.The average particle size of aeolian sand in the study area ranged from 2.04 to 2.10Φ,and the sorting of the aeolian sand soil was medium or good.The skewness of soil particles was nearly symmetric,and the kurtosis curve distribution was medium.There was a certain correlation between mean particle size and standard deviation,skewness and kurtosis,and the correlation was different among different geomorphic parts.The mean grain size of the site among sand dune was positively correlated with standard deviation and skewness,but negatively correlated with kurtosis.The mean particle size of leeward slope was positively correlated with standard deviation,skewness and kurtosis,but the correlation coefficients were small.The parameters of windward slope have the least correlation.