Fukui M
Health Phys. 1987 Aug;53(2):181-6.
Concentration profiles of 222Rn and their variations were studied to understand the vertical motion in the ground caused by fluctuations of meteorological parameters, such as precipitation, ground-water level and atmospheric pressure. A method of trapping 222Rn was developed to measure the concentration profiles by circulating and bubbling soil gas in porous cups into toluene. For locations where the water table is close to the surface, observations showed a peak concentration in the vertical profile of 222Rn at about a 40-cm depth and revealed that the concentration in soil gas decreases as soil moisture increases near the water table. Soil gas in a buried vessel also was circulated continuously to monitor 222Rn in the ground air near the surface using an ionization chamber. A rising of the water table following precipitation causes a burst of 222Rn concentration by upflow in the ground, though the concentration in the soil gas soon decreases with the intake of air above the surface due to increasing atmospheric pressure following precipitation. The concentration in soil gas again increases via the phenomenon accompanying the recovery of equilibrium in soil water between 222Rn and 226Ra.
研究了²²²Rn的浓度分布及其变化，以了解由降水、地下水位和大气压力等气象参数波动引起的地面垂直运动。开发了一种捕获²²²Rn的方法，通过使多孔杯中的土壤气体循环并鼓泡到甲苯中来测量浓度分布。对于地下水位接近地表的位置，观测结果显示²²²Rn垂直分布在约40厘米深度处有一个峰值浓度，并表明随着地下水位附近土壤湿度的增加，土壤气体中的浓度会降低。还通过电离室对埋入容器中的土壤气体进行连续循环，以监测地表附近地面空气中的²²²Rn。降水后地下水位上升会导致地面²²²Rn浓度因向上流动而突然增加，尽管由于降水后大气压力增加，地表上方空气的进入会使土壤气体中的浓度很快降低。土壤气体中的浓度会通过²²²Rn与²²⁶Ra之间土壤水恢复平衡所伴随的现象再次增加。
