贵州高原面岩溶丘陵坡地土壤侵蚀速率核示踪法研究
文献类型：学位论文
| 作者 | 严冬春
|
| 学位类别 | 硕士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 文安邦 |
| 关键词 | 土壤侵蚀 岩溶坡地 贵州高原面 137Cs 异质性 空间分布 |
| 学位专业 | 自然地理学 |
| 中文摘要 | 岩溶山区具有多相多层复杂界面体系，环境界面变异敏感度高、环境容量低、稳定性差、承受灾害能力弱。为了调查贵州高原面岩溶坡地土壤侵蚀强度，指导石漠化治理，应用自制的简易工具调查了贵州高原面岩溶坡地土壤异质性，讨论了岩溶坡地土壤异质性的表述方法；尝试137Cs法示踪了岩溶坡地土壤侵蚀情况，采集了贵州高原面137Cs本底值，分析了岩溶坡地137Cs的空间分布；结合径流小区观测资料，调查了洼地和小流域出口沉积泥沙中137Cs含量，并讨论了土壤地面流失与地下流失之比。主要结论如下：（1）选取了地表石质土地面积比例及空间分布和土壤厚度及空间分布两个方面作为土壤空间异质性的表述内容，引入了地块破碎度、离散度、变异函数等指标；以王家寨为例，研究发现岩溶坡地土石比、破碎度、离散度、土壤厚度等指标从坡顶到坡脚逐渐增大；石质地块破碎度在微观地块上表现为值越大地块越完整，是否与研究尺度有关还需要进一步论证；土壤厚度变异系数基本在1~1.5之间，与岩溶坡地土壤厚度变程和土壤平均厚度有关。（2）龙里草原土壤中137Cs的平均面积活度为955.3Bq/m2。普定土壤中137Cs的平均面积活度为886.5Bq/m2。考虑到贵州高原面不同水气来源对137Cs沉降量的影响，本研究137Cs本底值为龙里与普定的平均值920.9 Bq/m2。（3）王家寨岩溶坡地土壤中137Cs的深度分布坡顶和坡脚具有相同的趋势，次表层土壤中137Cs的比活度最大；坡中土壤中137Cs的含量先增加后陡然减少，可能是由于小于2mm的土壤颗粒向下渗漏。土壤中137Cs的比活度介于9.1－56.9Bq/kg之间，变化趋势顺坡降低，与土层厚度变化趋势相反；平均比活度为26.1Bq/kg，远远大于本底值的137Cs比活度，可能是由于岩溶坡地土层较薄，同时基岩表面沉降的137Cs也流入土壤中，导致单位土壤接收的137Cs含量增大。土壤中137Cs的面积活度介于144.7－440.2Bq/m2之间，顺坡变化趋势不明显；与本底值比较，流失比较大；可能是由于黔中岩溶坡地早期石漠化较严重，基岩无法吸附137Cs，导致早期沉降的137Cs随水流失。基于目前的研究方法和模型，有理由认为用于均质土壤地区的137Cs法暂时不适合直接用于基岩型岩溶坡地土壤侵蚀速率的调查。（4）普定陈旗小流域6种径流小区调查的2007年平均土壤侵蚀强度基本上小于10t/km2a，三个洼地通过137Cs法断代除石人寨洼地由于1960年前后植被破坏殆尽导致泥沙沉积量巨大外，马关和中坝洼地产沙模数均小于30 t/km2a。 |
| 英文摘要 | In order to survey soil erosion on karst slope of Guizhou plateau and guide soil and water conservation, firstly, this paper did research on the soil spatial heterogeneity in karst zone and discussed the expression methods. Secondly, we investigated the distribution of Caesium-137 in karst soil. Thirdly, we chose 3 depressions to study sediment deposition modulus and find the soil erosion rate on 6 runoff plots. Underside is the particular results:To express effectively the soil spatial heterogeneity in karst zone, we chose the proportion of rock area on overland and the rock area’s spatial distribution and the depth of soil and its spatial distribution as research fact. We made a wooden block to extract information of overland, which include spatial distribution of rock plague and the rock plague’s area. The depth of soil was measured by a steel drill which was calibrated scale per centimeter and then the depth information was expressed by equal depth linear figure. The fragmentation and dispersion were utilized to quantitatively describe the proportion of rock area on overland and the rock area’s spatial distribution and the variable function was used in soil depth variety. Then we sampled the Wangjiazhai slope and found that the indexes included the proportion of soil area, fragmentation, dispersion and mean soil depth were enlarged from upper slope to bottom slope. In theory the value of rock area fragmentation is bigger means the area more cracked. But it was opposite in our study. Nevertheless, it required more experiments to testify whether the result is reverse between microscopic landform and macroscopic landform. The value of variable index ranged from 1 to 1.5，which is decided by the extent of soil depth and the mean soil depth. Finally, we tried to explain the soil spatial heterogeneity by soil erosion principle.The inventory of Caesium-137 in Longli grass land is 955.3Bq/m2, and the inventory in Puding county is 886.5Bq/m2. Considering the different source of hydrosphere in Guizhou plateau, this paper chooses the average inventory of Longli and Puding.The concentration of Caesium-137 in soil of Wangjiazhai slope is 9.1－56.9Bq/kg, and the average is 26.1Bq/kg, which is too bigger the concentration in no erosion site. The depth diffusion of Caesium-137 in soil is not fit to index distributing, and the concentration of Caesium-137 in second layer soil is most than other sites. The concentration of Caesium-137 in middle slope, first to increase, and than decrease, for two reasons: for one hand is the soil particle whose diameter is smaller than 2 mm leaks out, for the other hand is the soil from upper slope deposit on the middle slope. The inventory of Caesium-137 is 144.7－440.2Bq/m2, comparing with no erosion site is smaller, it is said that the quantity of erosion is bigger. And the reason is likely that the Caesium-137 had flown to lake when the Caesium-137 fell out, because the early plateau surface is lack soil and the Caesium-137 is hard to be absorbed. Base on resently research methods and models, we can consider that the Caesium-137 method is not fit to trace soil erosion on karst slope temporarily.The modulus of soil erosion from 6 runoff plots in Puding county are smaller than 10 t/km2a. Exception Shirenzhai depression whose vegetable is destroyed in 1960s, other two depressions’ sediment deposition modulus of soil is smaller than 30 t/km2a. |
| 学科主题 | 土壤学 ; 水土保持学 |
| 语种 | 中文 |
| 公开日期 | 2010-10-15 |
| 分类号 | S15;S14 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2223]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） 成都山地灾害与环境研究所_山地表生过程与生态调控重点实验室 |
| 推荐引用方式 GB/T 7714 | 严冬春. 贵州高原面岩溶丘陵坡地土壤侵蚀速率核示踪法研究[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2008. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。