Thermo-diffusional radon waves in soils.
Thermo-diffusional radon waves in soils.
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DOI：
10.1016/j.scitotenv.2016.04.131
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发表时间：
2016-09
期刊：
影响因子：
--
通讯作者：
L. Minkin;A. S. Shapovalov
中科院分区：
文献类型：
--
作者：
L. Minkin;A. S. Shapovalov
提出了土壤和露天环境中氡浓度日变化和季节变化的新理论框架。该理论基于土壤中存在的温度波和多孔介质中的热扩散气体通量。由于土壤是一种非等温多孔介质，通常具有很大一部分属于努森自由分子场的微观孔隙，土壤中必然会出现热扩散气体流动。求解了土壤-大气边界正弦温度振荡时土壤中氡的传质方程，结果表明，土壤中的氡浓度表现为一种阻尼谐振波。氡浓度振荡的幅度和氡浓度振荡与土壤温度之间的相移取决于土壤中的氡扩散系数、产氡速率、土壤导热系数、平均地温、衰变常数和氡迁移热。给出了初步的数值计算，并与实验数据进行了比较。
A new theoretical framework for diurnal and seasonal oscillations of the concentration of radon in soil and open air is proposed. The theory is based on the existing temperature waves in soils and thermo-diffusional gas flux in porous media. As soil is a non-isothermal porous medium, usually possessing a large fraction of microscopic pores belonging to Knudsen's free molecular field, a thermo-diffusional gas flow in soil has to arise. The radon mass transfer equation in soil for sinusoidal temperature oscillations at the soil–atmosphere boundary is solved, which reveals that radon concentration behaves as a damped harmonic wave. The amplitude of radon concentration oscillations and phase shift between radon concentration oscillations and soil temperature depend on the radon diffusion coefficient in soil, rate of radon production, soil thermal conductivity, average soil temperature, decay constant, and heat of radon transfer. Primarily numerical calculations are presented and comparisons with experimental data are shown.