粤北岩溶山地土壤垂直渗漏与粒度变化特征

选择广东粤北连南两个典型岩溶山地剖面，调查了剖面裂隙、漏斗等的垂直分布特征，采样分析了土壤粒度垂向变化。结果表明：碳酸盐岩的构造运动、差异风化和溶蚀等形成的裂隙、漏斗和孔穴在降水入渗、土壤自重力和溶蚀作用下成为土壤地下迁移的通道；漏斗、裂隙及孔穴主要分布在0-10 m的范围，根据横断面调查计算，漏斗土壤占整个断面面积的23.1%-28.1%，裂隙土占整个断面面积的5.3%-8.9%，孔穴土占0.16%，土壤面积占整个剖面面积的28.4%-37.16%。在漏斗和裂隙中土壤颗粒物以粗粉沙和砂粒为主，次为粘粒和细粉沙，随深度增加砂粒含量降低，粘粒含量总体呈增加趋势但其变化与漏斗和裂隙底部形态、角度、宽度等有关；土壤粒度分布特征证明岩溶山地土壤存在水平和垂直两个运移过程以及地表侵蚀、土壤细粒物质下渗和土壤细粒物质堆积三个迁移阶段。

Vertical distribution of migration channels and grain-size change features of soil in karst mountainous areas of northern Guangdong

In this paper, we selected two typical profiles in karst mountainous area of Liannan county, Guangdong province, the underground distribution feature of funnels and crack were investigated and grain-size parameters were measured. The results show that, main underground transport channels of soil are funnels, cracks and caves, which are formed by differential weathering of carbonate rock, abundant rainfall infiltration, gravity and corrosion. Funnels, cracks and caves distribution depends primarily on the rock composition and the joint structure, and surface range of 0-10 m is the main distribution area. The funnel soil area accounted for 23.1%-28.1% of the total cross-sectional area, while the crack soil area occupied 5.3%-8.9% of the total area, and the hole soil area is only 0.16%. The total soil area in the profiles accounted for 28.4%-37.16% of the total area of profiles. Soil grain-sizes underground are mainly coarse silt and sand, followed by clay and fine silt. The vertical grain-size distribution of soil in the funnel and crack proves that there are two processes of soil migration: the horizontal erosion and vertical leakage. There are three soil migration stages: surface erosion, infiltration of fine-grained soil material, and accumulation of fine-grained soil material in the karst mountains. The main driving force of the soil migration leakage is soil gravity and the infiltration of water gravity.