摘要
137Cs背景值的确定是利用核示踪技术研究土壤侵蚀的前提和根本,直接关系到侵蚀速率计算的准确与否。而大部分研究对137Cs背景值的确定均采取随机采样,没有统一的采样点数与确定的采样面积。本研究利用网格加密采样法,对未扰动地和长期耕种且未平整的农耕地各两块样地的137Cs背景值空间变异进行了分析,结果表明:在未扰动地与农耕地采样地块,137Cs采样点数与背景值空间变异系数都存在指数回归关系;在未扰动地块137Cs背景值存在较大空间变异性,且随着网格面积的扩大137Cs空间变异系数表现为增加趋势,在0.25m2范围内选取最少11个样点才能满足试验精度;在农耕地采样地块,因长期的耕种作用使得137Cs在耕层中混合相对均匀,137Cs背景值空间变异性显著变小,最少选取7个样点就能满足试验精度,且不受采样面积的影响。
Confirmation of the ^137 Cs reference inventory is the premise and foundation of using ^137 Cs technique to study soil erosion. However, most investigators made the ^137 Cs reference inventory using haphazard approach and lacked the uniform sampling numbers and sampling area. The sampling method of gradually increased grid density was used to study the spatial variation of ^137 Cs reference inventory on undisturbed land and cultivated land in this paper. The results indicated that ^137 Cs inventory showed spatial variation greatly on the undisturbed area. The exponential regression appeared between the number of reference points and CV. With the increasing of grid area, the coefficient of variation of ^137 Cs content displayed the increased trend. And to satisfy the required accuracy of experiment, at least 11 points should be sampled in the area of 0.25m^2. However, due to long-term cultivation on crop land, the ^137 Cs content was mixed uniformly within the plough layer, and the spatial variation decreased obviously. The sampling numbers Of reference points had also the exponential regression relationship with CV. At least 7 points should be sampled to reach accuracy of experiment, and the sampling numbers were not affected by sampling area.
出处
《核农学报》
CAS
CSCD
北大核心
2009年第3期482-486,共5页
Journal of Nuclear Agricultural Sciences
基金
国家科技支撑计划(2006BAD09B05)
教育部“新世纪优秀人才”支持计划
关键词
^137Cs背景值
网格采样
空间变异
^137 Cs reference inventory
grid sampling
spatial variability
