Preliminary Study on a Regional Radon Concentration in Surface Soil Prediction Method

Abstract

A reformulated mathematical equation for predicting radon concentration in surface soil has been established based on the diffusive and convection theory. The parameters in the equation, such as radon emanation coefficient, convection velocity, diffusion coefficient, porosity of soil and so on, are closely related to the soil types. In order to determine these parameters, field measurement were carried out in totally 31 sites covering four types of soil in Chengdu Area, China. And least squares fitting algorithm and inversion fitting computation were also used. The prediction equation is ultimately applied to map the radon concentration in surface soil of Chengdu Area along with the geochemical databases of uranium content distribution in soil and soil texture distribution. According to the field measurement results on 17 sites in Chengdu, the prediction was verified to work property.

Mathematical Expressions of Radon Measurements

“…Since radon is produced continuously from decay of radium in natural decay chains of uranium, the rate of change of the number of radon atoms is determined by radon decay and generation of radon in the decay of radium present in closed can Figure 1. Since radium present as solid and radon as gas, in order to find the rate of change of the number of radon atoms in the air-filled pore space, assuming that [1,4].…”

Environmental factors influencing the spatial distribution of geogenic radon sources (uranium, radium) in a granitic area

“…𝐶 ∞ : maximal radon concentration in soil air at large depth available for transport (Bq m -3 ) 𝐶 𝑅𝑎 : radium activity mass concentration of the material (Bq kg -1 ) 𝜀: emanation coefficient (dimensionless), 𝜌 𝑏𝑢𝑙𝑘 𝑑𝑟𝑦 : bulk density (kg m -3 ) 𝑝 𝑒 : effective porosity This relationship has been widely applied in its original form and with slight variations (Chitra et al, 2018;Cosma et al, 2001;Ielsch et al, 2002;Ishimori et al, 2013;Jiang et al, 2011;Moldrup et al, 1998;Nazaroff and Nero, 1988;Pereira et al, 2017;Petersell et al, 2015;Washington and Rose, 1992;Yakovleva, 2005).…”