石羊河尾闾青土湖表层土壤粒度空间分布特征

Characteristics of Spatial Distribution of Surface Soil Particle Size in Qingtu Lake at the End of Shiyang River

[目的]揭示石羊河尾闾青土湖土壤粒度空间分布特征,为该区域生态恢复提供理论依据。[方法]以湖区为中心分别在西北、正东、东南方向上布设样线并采集0—20 cm深度土壤样品,对比分析了青土湖周边不同区域沙物质粒配组成、粒配曲线等参数特征。[结果](1)青土湖表层土壤粒度组成以细砂为主(26.26%~84.97%),其中西北方向上表层土壤粒度以细砂为主(26.26%~66.62%),其次是粉粒(4.23%~46.35%);正东、东南方向上表层土壤粒度组成以细砂为主(43.41%~86.30%),其次是极细砂(1.86%~29.60%)。不同样线同粒级间含量存在差异。(2)研究区表层土壤颗粒总体较粗,分选较差,偏度为正偏度,峰度属尖窄。粒度参数的空间分布表现为:西北方向表层土壤平均粒径较其他方向偏细,分选性较差,偏度也更为正偏,峰值小于正东方向。正东、东南方向表层土壤平均粒径较为一致,明显偏粗,分选性分别属中等、较好,均为近于对称,峰度为尖窄、中等。(3)西北方向土壤粒度频率平均值分布曲线表现为双峰型,正东、东南方向为单峰型。粒度累计分布曲线反映出,东南方向风沙活动较正东、西北方向频繁、强烈。(4)通过沉积环境判别得出西北方向主要是湖相沉积,正东、东南主要是风成沉积。[结论]成土过程和干旱多风的环境条件影响青土湖土壤的基本特性,而通过生态输水形成水面改善了该区的土壤环境。

[Objective]The aims of this study are to reveal the characteristics of spatial distribution of soil grain size in Qingtu Lake at the end of Shiyang River,and to provide theoretical basis for ecological restoration in this region.[Methods]Sampling lines were set up in the northwest,east and southeast directions of the lake area.Soil samples at a depth of 0—20 cm were collected to compare and analyze the parameter characteristics of particle composition and particle size distribution curves in different areas around Qingtu Lake.[Results](1)The particle size composition of the surface soil of Qingtu Lake is mainly composed of fine sand(26.26%~84.97%),with fine sand being the main particle size in the northwest direction(26.26%~66.62%),followed by silt(4.23%~46.35%).The particle size composition of the surface soil in the east and southeast directions is mainly composed of fine sand(43.41%~86.30%),followed by extremely fine sand(1.86%~29.60%).There are differences in contents between different sample lines and the same particle size.(2)The surface soil particles in the research area are generally coarse and poorly sorted,with a positive skewness and a sharp and narrow kurtosis.The spatial distribution of particle size parameters shows that the average particle size of the surface soil in the northwest direction is finer than that in other directions,with poor sorting ability and more positive skewness,with a peak value smaller than that in the east direction.The average particle size of the surface soil in the east and southeast directions is relatively consistent,significantly coarser,with medium and good sorting properties,both of which are nearly symmetrical,and the kurtosis is narrow and medium.(3)The average distribution curve of soil grain size frequency shows a bimodal pattern in northwest direction,and a unimodal pattern in due east and southeast direction.The cumulative distribution curve of particle size reflects that the wind and sand activities in the southeast direction is more frequent and intense than those in the due east and northwest directions.(4)Through sedimentary environment discrimination,it can be concluded that the northwest direction is mainly lacustrine sedimentation,while the due east and southeast are mainly eolian sedimentation.[Conclusion]The soil formation process and arid and windy environmental conditions affect the basic characteristics of the soil in Qingtu Lake.The soil environment in this area is improved by ecological water transport to form water surface.