A geostatistical investigation of the spatial variation of radon in soil

Concern about possible links between emissions of radon (Rn) and certain ty pes of malignant disease has led to surveys to measure Rn concentrations in the soil and in dwellings. There is little information about the spatial s cales of Rn variation in bedrock and soil. Such information on Rn is needed to effectively sample it in order to measure for spatial prediction. To ex plore the spatial variation of Rn concentration in soil gas, it was measure d using solid-stale nuclear track detection in a Rn affected area in the En glish Midlands. Three surveys are described which show different sampling a pproaches for exploring spatial variation. The first was a nested survey wi th seven stages conducted near Burton in Derbyshire (UK), in an area compri sing three principal lithologies (two limestones and a sandstone). The othe r surveys were south of Burton on the Monsal Dale limestone. One was an irr egularly distributed sample in two dimensions in which Rn concentration, pa rticle size distribution, and elevation were recorded. The other was along a transect 2km long. In addition to Rn concentration, ground conductivity a nd slope angle were measured at 20m intervals. The results of the nested su rvey suggest that geology exerts a strong control on Rn variation, and thos e of the other two surveys that other factors are also involved, such as el evation, soil depth, and soil particle size distribution. (C) 2001 Elsevier Science Ltd. All rights reserved.