侵蚀性风化花岗岩坡地不同地貌部位土壤剖面风化特征研究

发布时间：2018-05-18 02:29

本文选题：侵蚀性坡地 + 土壤剖面　；参考：《浙江大学》2017年硕士论文

【摘要】：严重的土壤侵蚀强烈影响着坡地土壤剖面的发育特性,在同一母质条件下,不同的侵蚀强度,其土壤剖面的风化程度以及孔隙特性差异很大。为了揭示不同地貌部位不同侵蚀强度对土壤剖面演化的影响,研究所选土壤剖面为:浙江省嵊州市水土保持监测站典型的侵蚀性风化花岗岩坡地,同一坡面不同侵蚀强度的坡地顶部、坡地中部、坡地下部的3个剖面。本研究以土壤剖面的孔隙特性及风化强度为两项主要讨论指标,通过3个土壤剖面分层样品和原状土柱的采集,各样品土壤基本理化特性和化学全量的分析,进而计算了3个剖面不同层次的主要化学风化系数及总的风化强度。利用CT扫描,对原状土柱的土壤孔隙特性进行高密度的数据获取,分析了不同地貌部位3个土壤剖面的总孔隙和大孔隙的分布特征以及影响因素。在上述分析的基础上,讨论了不同地貌部位、不同侵蚀强度、土壤剖面不同深度孔隙特性和风化强度的对应关系,得如下结论:(1)土壤剖面总的风化强度不大,上下层的递变差异很小,脱硅富铝化过程随着剖面深度的增加风化程度越来越弱。土壤剖面的化学风化分层不明显,各种风化指标均在60 cm左右形成了一个分界层,其上受水力侵蚀影响明显,其下呈现出的特性以继承残积母质为主。位于不同地貌部位的土壤剖面风化发育程度排序为:坡底坡中坡顶,其与采样坡面的侵蚀强度排序正好相反。(2)风化程度与有机质和黏粒含量具有较为明显的正比关系,在侵蚀环境下,土壤的物理特性对风化的影响明显,在沉积环境下土壤有机质的影响大于黏粒含量的影响。总之,由于受侵蚀的影响,坡地土壤剖面的淀积层不发育,剖面呈现出的假淀积层不是由淋溶作用形成的,而是具有一定风化程度的风化残积层,结果导致发育于山地丘陵侵蚀性坡地的土壤层次划分不同于常规的土壤层次划分。(3)3个土壤剖面总孔隙度都是随着剖面深度的增加而减小,并以大孔隙为主。孔径在1～3mm所占比重最大,5～7mm所占比重最小。同一坡面不同地貌位置3个土壤剖面的大孔隙个数比例的排序为:坡中坡底坡顶。3个土壤剖面的大孔隙度与总孔隙度的差值都很小,并随着深度的变化而递减。在3个土壤剖面中大孔隙度大于平均值的层位主要分布在0～30cm深度之间。大孔隙度的平均值以坡顶最大(35.18%),坡中次之(33.18%),坡底最小(30.64%)。大孔隙的成圆率影响大孔隙度与总孔隙度的关系。土壤黏粒和粉粒含量越多,成圆率越大。(4)总孔隙度,大孔隙度与风化强度之间一致性受到侵蚀的影响,侵蚀强度越大,它们之间的一致性越差,侵蚀强度越小,它们之间的一致性越好。在整个土壤剖面中风化强度值的变化范围不大,对侵蚀强度指示的灵敏度具有迟缓性,而土壤孔隙特性的指示灵敏度高于风化强度。(5)在强烈侵蚀的花岗岩风化残积坡地发育的土壤,总体发育成熟过程较弱,其进一步的发育与典型的地带性土壤的发育有很大的差异。侵蚀强度越大,则土壤发育越差,最大风化强度不是在土壤表层,而是在表层以下的一定深度,风化强度最大值的层位,即为水力侵蚀的最大影响深度。土壤侵蚀强度越大,土壤剖面大孔隙度所占的比例越大。
[Abstract]:Serious soil erosion strongly affects the development characteristics of soil profile in the slope. Under the same parent material, different erosion intensity, the difference of weathering degree and pore characteristics of the soil profile is very different. In order to reveal the influence of different erosion intensity on the soil profile evolution in different geomorphologic parts, the selected soil profile is Zhejiang Shengsheng. The typical erosive weathered granite slope in the soil and water conservation monitoring station of the state city is the top of the slope with different erosion intensity on the same slope, 3 sections in the middle of the slope and the lower part of the slope. In this study, the pore characteristics and weathering strength of the soil profile are two main discussion indexes, and the collection of the stratified samples and the original soil columns in 3 soil profiles is collected. The main chemical weathering coefficient and total weathering intensity of the 3 sections were calculated by the analysis of the basic physicochemical properties and chemical total quantity of the soil. The soil pore characteristics of the original soil column were obtained by CT scanning, and the distribution of the total pore and the large pore in the 3 soil profiles at different geomorphic parts was analyzed. On the basis of the above analysis, the corresponding relationship between different geomorphic parts, different erosion intensity, different depth pore characteristics and weathering intensity of soil profile is discussed. The following conclusions are as follows: (1) the total weathering intensity of the soil profile is not large, the variation of the upper and lower layers is very small, and the process of desilication and aluminizing increases with the depth of the section. The weathering degree is getting weaker and weaker. The stratification of the chemical weathering of the soil profile is not obvious. All weathering indexes have formed a demarcation layer around 60 cm, which are influenced obviously by the hydraulic erosion. The characteristics of the soil profile are mainly inherited from the residual parent material. The weathering development of the soil profile at different geomorphic parts is ranked as the top of the middle slope of the slope. It is the opposite of the erosion intensity on the slope surface. (2) the degree of weathering and the content of organic matter and clay particles have a more obvious positive ratio. In the environment of erosion, the physical properties of soil have obvious influence on the weathering, and the influence of soil organic matter in the sedimentary environment is greater than the effect of the clay content. In a word, the slope is affected by erosion. The sediment layer in the soil profile is not developed, and the false accumulation layer is not formed by leaching, but is a weathering residual layer with a certain degree of weathering. The results lead to the classification of soil layers developed on the eroded slope of the hills and hills. (3) the total porosity of the 3 soil profiles is all along with the profile. With the increase of surface depth, the main pore size is large pore. The proportion of pore size from 1 to 3mm is the largest and the proportion of 5 ~ 7mm is the smallest. The proportion of large pore numbers in 3 soil profiles with different geomorphologic positions on the same slope is: the difference between the large porosity and the total porosity of the.3 soil profile at the top of the slope bottom is small, and changes with the depth. In 3 soil profiles, the large porosity larger than the average is mainly between 0 and 30cm depth. The average value of the large porosity is maximum (35.18%), the secondary (33.18%) and the bottom of the slope (30.64%). The relationship between the large porosity and the total porosity is influenced by the macroporosity. The more the clay and powder content, the more the content of the clay and the grain is formed. The greater the roundness. (4) the total porosity, the consistency between the large porosity and the weathering intensity is affected by erosion, the greater the intensity of the erosion, the worse the consistency between them, the smaller the erosion intensity, the better the consistency between them. The variation of the weathering intensity value in the whole soil profile is not large, and the sensitivity of the erosion intensity indication is slow. The indicator sensitivity of soil pore characteristics is higher than that of weathering intensity. (5) the soil developed in the strongly eroded granite weathering residue slope is weaker in overall development, and its further development is very different from that of typical zonal soil. The greater the erosion intensity, the worse the soil development, the maximum weathering intensity is not. On the surface of the soil, but at a certain depth below the surface, the maximum depth of the weathering intensity is the maximum influence depth of the hydraulic erosion. The greater the soil erosion intensity, the greater the proportion of the large porosity in the soil profile.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157;S151.1

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