Meteorological parameters contributing to variability in 222Rn activity concentrations in soil gas at a site in Sapporo, Japan

Abstract

Continuous 222Rn monitoring in soil gas since November 22, 2004 has revealed variability in activity concentration with time in the semi-natural woods on the campus of Hokkaido University in Sapporo, Japan. Among various factors affecting soil radon levels and variability, temperature was found to be dominant during three seasons when activity concentrations of 222Rn showed a diurnal high and nocturnal low with a boundary around 10 o'clock in the morning. This pattern was disturbed by low pressure fronts with occasional rain. The activity gradually decreased as soil temperatures decreased from late November to mid-December. After the ground surface was completely covered with snow, soil radon levels became low with a small fluctuation. There were several peaks of 222Rn on the time-series chart in winter. Those peaks appearing in early winter and early spring may be interpreted by considering meteorological parameters. In a few cases, the radon activity suddenly increased with increasing pressure in the soil at a depth of 10 cm, which may be associated with subsurface events such as seismic activity in the area

Depth profiles of potassium and its isotope ratio (40K/K) in several forest soils

“…6 In the observation site in Sapporo soil sampling was carried out in different seasons to investigate seasonal variation of the soil properties including environmental radionuclides ( 226 Ra, 137 Cs and 210 Pb) other than 40 K. Radon ( 222 Rn) and CO 2 (and its carbon isotopes,  13 C and  14 C) have also been monitored in this site since 2002. 5,10,11,17 It is interested to note in Table 1 that the amount of soil organic matter varied in winter-high and summer-low under a deciduous stand in Sapporo.…”

Tracing the sources of gaseous components (222Rn, CO2 and its carbon isotopes) in soil air under a cool-deciduous stand in Sapporo, Japan

“…The 222 Rn level usually remained low under thick snow cover in winter. However, 222 Rn peaks were sometimes observed with increasing barometric pressure in soil air (Fujiyoshi et al 2006). While its physical origin is known ( 226 Ra), the actual point of origin of 222 Rn in terms of certain soil layers, minerals or grain size fractions, and its pathway into other environmental compartments have not been sufficiently elucidated (Breitner et al 2008).…”

Natural and anthropogenic consequences of tropical forest soils in Northern Peru using environmental radionuclides as radiotracers

“…They showed applicability of these nuclides of different origin and of chemical properties as tracers for tracking natural and anthropogenic transition under various temperate stands in Germany and Czech Republic as well as on the campus of Hokkaido University in Sapporo, Japan. [4][5][6][7] The purpose of the this study is to elucidate natural and anthropogenic consequences on tropical forest soils in northern Peru where little intervention by men has been encountered so far using several environmental radionuclides ( 40 K, 137 Cs, 210 Pb and 226 Ra) as natural tracers. Figure 1 shows the location map of investigation sites (El Angolo and Alto Mayo) in Northern Peru.…”