Spatial and temporal variations of radon concentration in soil air

The spatial and temporal variability of the soil gas radon concentration in typical soils is studied. The results obtained will be further used to predict indoor radon levels. To this end, 50 measuring points along geologic sections with known physicogeological parameters of soils were chosen. The soil gas radon concentration was measured with SSNTDs (Type III-b) at a depth of 70 cm from June to October, 2000. The radon exposure time was 72-96 h. The average radon concentration in the soil pore air for an urban area was 11 kBq m ^-3 (1.7-24 kBq m^-3). Small-scale spatial variations in the concentration were found to lie within a narrower range. The effect of meteorological conditions on the soil gas radon concentration was investigated by performing 8 series of measurements at 5 closely spaced points in September-October, 2000. A significant correlation was found between the soil radon concentration and atmospheric pressure (K = -0.86), ambient temperature (K = 0.75), and soil temperature (K = 0.75).