摘要
通过对高寒草原背景值样点(RS7)的分析,将共和盆地的137Cs背景值含量确定为(2691.78±196 08)Bq·m-2,基本接近北半球137Cs背景值的平均水平,其137Cs剖面满足尖峰分布函数,与公认的理论分布(即负指数分布)相比,呈现出峰值下移和曲线趋平的现象,可能与近几十年来137Cs的稳定下渗有关。应用137Cs背景值剖面分布函数,建立了风蚀速率的137Cs估算模型,估算出四个样方的土壤风蚀速率,并由此转化为区域风蚀速率,计算出共和盆地区域土壤风蚀速率为12 556t·hm-2·a-1,通过蚀积平衡检验,其误差水平小于10%。并分析了风蚀物的输出途径及其所占比例。
Analyzing results of the 137 Cs distribution along soil profile suggest that the cold grassland that maintained the relatively perfect profile of original 137 Cs fallout can be regarded as ideal sampling site of 137 Cs reference. Therefore the value of 137 Cs reference inventory of the Gonghe Basin is calculated to be ( 2 691.78 ±196 08) Bq·m -2 at the site of RS7, which is close to the globe average of the Northern Hemisphere. The depth distribution of 137 Cs activity fits the peak type remarkably, and comparing with the exponential type regarded as classical and theoretical one, it exhibites the descent of peak layer and smoothing of the 137 Cs curve, which is possibly related to stable infiltration of 137 Cs in recent decades. Therefore by means of the 137 Cs model derived from the 137 Cs reference distribution, the rate of wind erosion on the four sampling plots was estimated, and then transforming the point erosion estimates to the area, the rate of wind erosion in the Gonghe Basin averaged 12 556 t·hm -2 ·a -1 , which is in according with the erosion deposition equilibrium with a relatively small error less than 10%.
出处
《中国沙漠》
CSCD
北大核心
2003年第4期391-397,共7页
Journal of Desert Research
基金
国家自然科学基金(40001001)
国家重大基础研究规划项目(G2000048702)
"十五"国家科技攻关项目"沙区农田
草地土壤风蚀防治技术研究"课题(2002BA517A10)资助
