Evidence for nondiffusive transport of 86Rn in the ground and a new physical model for the transport

Abstract

Concentration of radon has been measured in the soil near the ground surface with solid‐state, nuclear track detectors with the inverted cup technique. Measurements were made in the overburden at depth intervals 0.1–0.7 m, at 0.1–6 m, and at a constant depth of 0.2 m, in a narrow rectangular matrix. The results disagree with the hypothesis that radon concentration only depends upon local production and migration by diffusion with a diffusion length of about 1 m. A transport length of 0.1–0.2 m is observed near the ground surface and the transport is dominated by a flow component. Radon measurements in the ground surface over the Laisvall lead mine have given evidence of radon transport through rock exceeding a distance of 100 m, which is possible only if the migration is a flow transport with a characteristic transport length larger than about 10 m/day. To explain the radon transport in the overburden and through the rock with a common transport system, the existence of a general upward flow of geo‐gas is proposed. This geo‐gas works as a carrier mechanism for radon. The physical conditions for the existence of a flow transport of radon are discussed.

Increased radon-222 in soil gas because of cumulative seismicity at active faults

“…This interpretation is evidenced by the simple kinetic transport of 222 Rn in the vertical direction in shallow soils. The transport can be expressed by the following mass balance equation, which combines molecular diffusion and advection of the carrier gas flow (Kristiansson and Malmqvist 1982;Ioannides et al 2003):…”

Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

“…The process (i), known as advection of geogas (Etiope and Martinelli, 2002) and can act as a major radon source in fractured rocks. CO 2 (together with other gases) works as a carrier gas for radon (Kristiansson and Malmqvist, 1982). While numerous fault zones are found along the Pisani rov (Šebela, 1992), this process may have a substantial role in controlling the concentration of radon and CO 2 in this passage.…”

Assessment of soil radon potential in Hong Kong, China, using a 10-point evaluation system

“…Radon anomalies observed near faults were generally due to the extra deposition of uranium from underground water (Al-Tamimi and Abumurad 2001;Hagmaier 1972) and additional transportation of radon along the facture zones (Kristiansson and Malmqvist 1982). The soil radon concentrations over granite 50 m within and outside of faults were quite similar due to two reasons (Fig.…”