摘要
在贵州茂兰峰丛洼地区的工程碑草地洼地典型小流域进行了洼地沉积泥沙137Cs示踪分析研究。研究结果表明:(1)草地洼地土壤剖面属于堆积土壤剖面,土壤剖面中137Cs浓度分布特征反映了泥沙堆积与表层土壤侵蚀的信息。受岩土分布、微地形的影响,137Cs初始沉降后出现不均匀再分布,面积活度的空间变化较大,变异系数为1.35,不能表征土壤侵蚀状况。(2)根据草地洼地典型堆积农耕地土壤剖面A-1的137Cs浓度分布特征,1963年以来的流域平均堆积泥沙数量是16.6t/km2.a,流域平均土壤侵蚀速率为45.95t/km2.a,约占侵蚀产沙数量63.88%的泥沙以地下流失的形式散失;(3)草地洼地小流域内地面土壤流失与地下土壤流失的相对贡献率分别是70.13%和29.87%;(4)以茂兰地区最大成土速率为依据推算出的允许土壤侵蚀量是13.51t/km2.a,草地洼地的土壤侵蚀危险程度极高。
Sand and clay sediments are studied by means of ^137Cs tracing test in typical grass-covered peak cluster depression in Maolan, southern Guizhou. It proves that：The grass-coveted soil profile in depression is formed by aecumulation, and the ^137Cs concentration variation with the depth of the profile reflects the information of sediment accumulation and surface soil erosion. Affected by earth-rock distribution and micro topography, the spatial redistribution of the ^137Cs after primary fallout is uneven, and ^137Cs inventories occurs greater spatial variation with the variation coefficient being 1.35, which shows that the ^137Cs inventory can not characterize the status of soil erosion. According to the ^137Cs concentration distribution along a typical profile A-1 , the sediment accumulation rate and the natural surface soil erosion rate are respectively 16. 6 t/ km^2 · a and 45.95 t/km^2 · a, which shows that about 63.88% of the eroded surface soil is removed by way of underground loss. The relative contribution ratio of surface soil loss and underground soil loss are respectively 70. 13% and 29.87%. By comparison to the utmost soil formation rate 13.51 t/km^2 · a in Maolan, the risk of soil erosion in the Engineering Monument grass-covered depression is higher.
出处
《中国岩溶》
CAS
CSCD
2009年第2期181-188,共8页
Carsologica Sinica
基金
国家重点基础研究发展计划项目(2006CB403203,2007CB407206)
中国科学院知识创新工程项目(kzcx2-yw-306)
中国科学院水土保持研究所国家重点实验室基金项目(10501-109)
关键词
137Cs含量
堆积剖面
草地小流域
侵蚀产沙
喀斯特峰丛洼地
茂兰
贵州
^137Cs content
accumulated profile
grassland small catchment
soil erosion and sediment yield
peak cluster depression
Maolan, Guizhou
