Almgren S, Isaksson M
Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden.
J Environ Radioact. 2006;91(1-2):90-102. doi: 10.1016/j.jenvrad.2006.08.008. Epub 2006 Oct 5.
The vertical migration of (137)Cs originating from nuclear weapons fallout (NWF) and the Chernobyl accident has been studied at 33 sampling sites in western Sweden. An attempt to describe the present depth distribution with a solution to the convection-diffusion equation (CDE) with a pulse-like fallout event as the initial condition was made. A sum of two CDEs describing the NWF and Chernobyl debris was fitted to the actual depth profiles measured by soil sampling. The fitted depth profiles were used to correct in situ measurements for the actual depth distribution, showing good agreement with the accumulated activities in soil samples. As expected, the vertical migration was very slow and most caesium was still present in the upper soil layers. The ranges of the apparent convection velocity, v, and apparent diffusion coefficient, D, were between 0 and 0.35 cm/year and 0.06 and 2.63 cm(2)/year, respectively.
在瑞典西部的33个采样点对源自核武器沉降物（NWF）和切尔诺贝利事故的（137）铯的垂直迁移进行了研究。尝试以脉冲状沉降事件为初始条件，用对流扩散方程（CDE）的解来描述当前的深度分布。将描述NWF和切尔诺贝利碎片的两个CDE之和拟合到通过土壤采样测量的实际深度剖面。拟合的深度剖面用于校正原位测量的实际深度分布，结果表明与土壤样品中的累积活度吻合良好。正如预期的那样，垂直迁移非常缓慢，大部分铯仍存在于上层土壤中。表观对流速度v和表观扩散系数D的范围分别在0至0.35厘米/年和0.06至2.63平方厘米/年之间。
