Kocher D C
Health and Safety Research Division, Oak Ridge National Laboratory, TN 37831-6383.
Health Phys. 1991 Apr;60(4):523-31. doi: 10.1097/00004032-199104000-00006.
A linear compartment model for global transport of iodine that we previously developed predicted that the mean residence time of iodine in the first 1 m of surface soil is about 4,000 y. An independent test of the model prediction is provided by measured depth profiles of (129)I in soil following atmospheric releases from the Savannah River Plant (SRP) in South Carolina and from the Karlsruhe fuel reprocessing plant in Germany. Previous analyses of these data using a linear compartment model for downward transport through soil indicated that the mean residence time in the first 0.3 m is about 40 y at both locations, which suggests that removal of (129)I from surface soil may be considerably more rapid than predicted by the global transport model. In this paper, a diffusion model is used to describe the measured soil profiles of (129)I at Savannah River. The diffusion coefficient obtained from the analysis corresponds to a mean residence time in the first 1 m of surface soil that agrees semi-quantitatively with the prediction of the global model when the concentration of naturally occurring stable iodine in soil and the flux of iodine from the atmosphere onto surface soil at Savannah River, as they differ from globally averaged values, are considered. This paper also discusses (1) the importance of the mean residence time of (129)I in surface soil for estimates of dose to individuals from near-surface land disposal of low-level radioactive wastes and (2) unresolved issues regarding global cycling of iodine.
我们之前开发的一个用于碘全球传输的线性隔室模型预测，碘在表层土壤前1米中的平均停留时间约为4000年。对该模型预测的一项独立检验来自于对南卡罗来纳州萨凡纳河工厂（SRP）以及德国卡尔斯鲁厄燃料后处理厂大气释放后土壤中¹²⁹I深度剖面的测量。此前使用一个用于描述¹²⁹I在土壤中向下传输的线性隔室模型对这些数据进行的分析表明，在这两个地点，¹²⁹I在0.3米深度内的平均停留时间约为40年，这表明¹²⁹I从表层土壤中的去除速度可能比全球传输模型预测的要快得多。在本文中，我们使用一个扩散模型来描述萨凡纳河土壤中¹²⁹I的实测剖面。从分析中获得的扩散系数对应于表层土壤前1米中的平均停留时间，当考虑到土壤中天然存在的稳定碘浓度以及萨凡纳河大气中碘向表层土壤的通量与全球平均值不同时，该平均停留时间与全球模型的预测在半定量上是一致的。本文还讨论了：（1）¹²⁹I在表层土壤中的平均停留时间对于估算低放废物近地表陆地处置对个人的剂量的重要性；（2）关于碘全球循环的未解决问题。
