砒砂岩与沙复配土壤的冻融特征

Freezing and Thawing Characteristics of Mixed Soil with Soft Rock and Sand

[目的] 揭示砒砂岩与沙复配土壤冻融特征及其对风蚀的影响，为毛乌素沙地土地整治可持续性提供理论依据。[方法] 利用陕西省榆林市榆阳区气象资料和土壤观测数据，结合含水量变化规律，以砒砂岩与沙复配土壤为研究对象，沙土为对照，探究2种土壤冻结层形成差异、冻融过程及积雪消融特点。[结果] 由于含水量的差异，复配土壤与沙冻结层形成特点具有差异，沙地表层通常会形成土壤干层，从表层之下冻结，而复配土壤的冻结层在地表形成；复配土壤的最大冻结深度为116.0 cm；大于沙地的最大冻结深度96.0 cm，且冻结层融解时间晚于沙地一周；积雪覆盖条件下，沙地表层存在1.0～6.4 cm的土壤干层，而复配土壤表层不存在干层，复配土壤积雪盖度和厚度均大于原始沙地，阳坡尤为显著。[结论] 土壤冻层和积雪在复配土壤地表形成了2层保护层，减少了休闲期的风蚀作用。

[Objective] The objective of the study is to reveal the freezing and thawing characteristics of the mixed soil and its effect on wind erosion and to provide a theoretical basis for the sustainability of the Mu Us sandland reclamation.[Methods] Taking mixed soil with soft rock and sand as the research object and sand as a control, the paper explored the differences in the freezing-layer formation, freezing-thawing processes and the snowpack melting of the two types of soil using meteorological data and soil and water content data of Yuyang District of Yulin City, Shaanxi Province.[Results] Due to the differences in water content, difference exists in the formations of the freezing layers between the two soils. Sandy soil was usually formed in dry layer and frozen under the surface while the mixed soil is frozen at the surface. The maximum frozen depth of mixed soil was 116.0 cm, deeper than that of the sand（96.0 cm）, and the freezing thawing time was a week later than the sand. When covered with snow, the surface of sand has 1.0 to 6.4 cm dry layer while the surface of mixed soil did not has. The snow coverage and thickness of mixed soil were greater than the sand, especially on the sunny slope.[Conclusion] Frozen soil layer and the snow could form two protective layers on the surface of mixed soil, and therefore reduce the wind erosion during the fallow period.