侵蚀性风化花岗岩坡地土壤发育特性

采用CT扫描技术、X射线荧光光谱仪化学全量分析和实验室土壤理化特性测试方法,对浙江省典型风化花岗岩坡地土壤发育的主要物理指标、化学风化系数及风化强度进行了测量计算,分析了侵蚀环境下不同地貌部位的土壤发育特征。结果表明:坡地土壤的发育程度较弱,土壤分层不明显,不同地貌部位的土壤风化发育程度排序为坡底<坡中<坡顶,与坡面侵蚀强度的排序正好相反。土壤物理风化指标随土层深度增加的变化规律较强,脱硅富铝化过程随着剖面深度的增加越来越弱,物理风化指标和化学风化指标具有同等作用的表征效果,不同于当地地带性土壤发育中以化学风化为主的特性。水力侵蚀强烈地区的最大风化强度位于20-40 cm处,推得水力侵蚀对土壤发育的影响深度为0-40 cm。

Characteristics of Soil Development on the Erosive Weathered Granite Slopes

To reveal the soil developmental characteristics on the erosive weathered granite slopes, soil samples of a typical weathering granite slope in Zhejiang Province were studied by the methods of CT scanning technique, X-ray fluorescence spectrometer and laboratory soil physicochemical properties test based on the principles of soil genesis and water erosion. The results showed that the total developmental degree of the soil samples was weak because the varying difference between the up and bottom layers was very small and the soil level-development was not obvious. The weathering intensity displayed an order of bottom profile < middle profile < top profile, which was just opposite to that in terms of the erosion intensity. The physical weathering indexes increased significantly with soil depth while the desilication process weakened. The varying range of chemical weathering intensity was not significant in the all soil profiles and it was different from the local zonal soil development which gave priority to chemical weathering features. Physical and chemical weathering indexes had the equal effect on describing the soil developmental characteristics. Water erosion affected the soil weathering processes and hindered the soil development to typical zonal soil. The maximum weathering intensity was between the surface layer of 20-40 cm, which indicated that the soil layer of 0-40 cm was greatly affected by water erosion.