毛乌素沙地布寨淖尔下风向沙化湖滨地表沉积物理化特性

The physicochemical characteristics of the surface sediments on dry lake bed in Buzhai-nur Lake,Mu Us Sandy Land,China

布寨淖尔湖是鄂尔多斯高原毛乌素沙地腹地的代表性盐湖,其东南部分布着平坦裸露的沙化湖滨\,湖岸沙丘及半固定沙丘,地表均沉积有大量沙物质与粉尘,这些松散富盐物质在风力侵蚀作用下常形成盐碱尘暴,威胁下风向区域的生态环境安全。研究了布寨淖尔湖东南部区域2.5 km范围内地表沉积物的土壤粒度与理化特性,旨在为盐碱尘暴源区的防治与生态治理提供基础科学参考。结果表明:布寨淖尔湖滨裸露地表沉积物以粗砂、中沙和细砂为主;从湖心沿东南方向等距离(0.5 km)采样,距湖心越远,粗砂和细砂含量逐渐减小,极细砂、粉砂和黏土含量逐渐增加,中砂含量无明显变化。地表沉积物含水率、容重随与湖心距离的增加逐渐增加,pH值、全盐量及电导率则呈逐渐减小趋势;沉积物阳离子以Na+为主,阴离子以Cl-为主,其次为SO4^2-、HCO3^-。整体看,区内地表碱化较为严重,区域下风向土壤理化特征呈明显有规律变化趋势,湖滨地表土壤有明显风蚀迹象,可能是盐碱尘暴与湖岸沙丘形成的重要物源区。

Buzhai-nur Lake is a representative salt lake in the hinterland of Mu Us Sandy Land.Flat and bare sandy lakeshore zone,lakeshore dune and semi-fixed dunes are widely distributed to the southeast of Buzhai-nur Lake.Abundant sand and dust that deposited on the surface of dry lake,are salt-rich and highly susceptible to saline-alkaline dust emission,threatening the ecological environment in the downwind areas.In this study,the grain-size and physicochemical characteristics of surface sediments within 0-2.5 km to the southeast of Buzhai-nur Lake were studied,aiming to provide basic scientific reference for the prevention and ecological management of the source area of saline-alkaline dust storm.Results show:(1)Surface sediments at the playa are predominantly coarse,medium and fine sand;(2)With increasing distance from the center of the lake,the fractions of coarse sand and fine sand decrease while the very fine sand,silt and clay gradually increase,and the medium sand dose not significantly change;(3)Soil moisture and bulk density of surface sediments increase,but pH,total salt content and electronic conductivity decrease as the distance increased from the center of the lake.Overall the results indicate that alkalization is serious in this area and the physicochemical properties exhibit remarkable trends in the downwind direction.Soils in the lakeshore zone have experienced significant wind erosion,which may be the important provenance of saline-alkaline dust storm and the formation of sand dunes in the lakeshore.