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砒砂岩与沙复配成土及其工程化核心技术的提出与应用,为毛乌素沙地合理利用土地资源、科学推进生态建设提供了新的思路与技术支撑。前期研究对利用层面的技术问题给予了较多关注并取得显著进展,而在潜在风险层面特别是关于复配土壤的固沙效应及其微观机理的探索则相对薄弱。基于集沙仪、扫描电镜及激光粒度仪,结合野外定位试验和室内仪器观测,对毛乌素典型原状沙地及复配农田的输沙特征差异及其固沙微观机理进行探索。结果表明:(1)观测周期内,原状沙地输沙总量为4 951 g,远高于复配农田2 436 g的输沙总量,原状沙地更易受风蚀,而复配农田土壤起沙风速大、输沙量较小,具有明显的固沙效应;(2)扫描电镜图像显示,原状沙地土粒(沙粒)粗骨化、无粘结,而耕种两年的复配农田土壤中已出现团聚体;(3)激光粒度仪分析显示,原状沙地的粉、黏粒含量仅为2.74%,而复配农田这一比例增至15.12%;(4)复配土防风固沙效应的形成与粉粒和黏粒含量及土壤结构等紧密相关。鉴于复配农田输沙固沙能力的动态差异性和风力敏感性,进一步实施复配成土造田工程时,宜在复配农田主导风向的上风向区域及成片农田内适当布设具有防风功能的适生草类或灌木条带。
The proposal and application of 砒 sandstone and sand compounding soil and its engineering core technology provide new ideas and technical support for the rational utilization of land resources and scientifically promoting ecological construction in Mu Us sandy land. Earlier studies paid more attention and made significant progress on the technical aspects of utilization. However, exploration on potential risks, especially on the effect of sand fixation and its micro-mechanism on compound soils is relatively weak. Sand sediment, SEM and laser particle sizer were used to investigate the difference of sediment transport characteristics and the microscopic mechanism of sediment transport in the typical undisturbed and mixed farmland of Mu Usu with the field experiment and indoor instrument observation. The results show that: (1) During the observation period, the total amount of sediment transport in intact sandy land is 4 951 g, which is much higher than the total amount of sediment transported by the 2 436 g farmland. The undisturbed sandy land is more susceptible to wind erosion. However, Sand velocity is large and sediment discharge is small with obvious sand fixation effect. (2) Scanning electron microscopy images show that coarse sand ridges (sand grains) (3) Laser particle sizer analysis showed that the content of powder and clay in the intact sandy land was only 2.74%, while the proportion of compound farmland increased to 15.12%. (4) The formation is closely related to the content of silt and clay and soil structure. Due to the dynamic and wind-susceptibility of sand-fixation and sediment-holding capacity of farmland, it is more appropriate to wind-proof farmland in the upwind area and into the farmland where the farmland is dominant Raw grass or shrub strips.