Hamada Hiromasa, Miyazaki Tsuyoshi
Japan International Research Center for Agricultural Sciences, Ohwashi 1-1, Tsukuba, Ibaraki, 305-8686, Japan.
J Environ Radioact. 2004;71(2):89-100. doi: 10.1016/S0265-931X(03)00143-7.
This paper describes an application of the quasi-partition law of radon-222 (222Rn) to a deep unsaturated vadose zone in a field. 222Rn is a very useful tracer to investigate not only saturated but also unsaturated water flows in vadose zones. Concentrations of 222Rn in water in unsaturated soils are, based on the quasi-partition law, lower than those in saturated soils. However, no study has previously applied quasi-partition law of 222Rn to analyze saturated and unsaturated water flows in vadose zones. In this study, we observed the applicability of existing theoretical equations of quasi-partition law of 222Rn experimentally. After confirming the validity of the theoretical equation, we applied this equation to estimate the unsaturated water flow in an actual vadose zone. By comparing the estimated degree of saturation from 222Rn measurement with that from a neutron moisture meter measurement, we obtained a beautiful agreement between them.
本文描述了氡 - 222（²²²Rn）的准分配定律在野外深层非饱和渗流带中的应用。²²²Rn不仅是研究饱和带中饱和水流，也是研究非饱和渗流带中非饱和水流的一种非常有用的示踪剂。基于准分配定律，非饱和土壤中水中²²²Rn的浓度低于饱和土壤中的浓度。然而，此前尚无研究将²²²Rn的准分配定律应用于分析渗流带中的饱和水流和非饱和水流。在本研究中，我们通过实验观察了²²²Rn准分配定律现有理论方程的适用性。在确认理论方程的有效性之后，我们应用该方程来估算实际渗流带中的非饱和水流。通过比较从²²²Rn测量得到的饱和度估算值与中子湿度计测量得到的饱和度估算值，我们发现二者吻合得很好。
