72
VARIABILITY OF RADON ACTIVITY CONCENTRATION IN SOIL GAS DUE TO CHANGES IN GROUNDWATER TABLE AND METEOROLOGICAL PARAMETERS -FIRST RESULTS OF A CONTINUOUS LONG TERM RADON MONITORING

M.Valdivia-Manchego * , R.Stegemann * , S.Leonardi + , K.Lehmann + and A.Siehl *
1 Institute of Geology, University of Bonn , Nussallee 8, 53115 Bonn, Germany + Institute of Geology, University of Bonn, Section Applied Geophysics,
Nussallee 8 , D-53115 Bonn, Germany

ABSTRACT
The evaluation of the geogenic radon potential is based on field measurements of radon activity
concentration in soil gas. The values obtained through such spot measurements depend strongly on
the geological background [1] [2] but also on the soil properties like grainsize distribution, pore-space
watersaturation and also on meteorological conditions. The goal of this study was to estimate
the variability of the radon activity concentration in soil gas and to relate it to the variations of soil
properties induced by seasonal changes. For this purpose, a long term monitoring of the variation of
radon activity concentration in soil gas has been carried out simultaneously to the registration of
soil and meteorological parameters at the Jülich Research Center (W-Germany) from February to
December 1997. The recorded time series should be used as a reference for the estimates of
seasonal variability for similar locations and help to interpret variations from spot measurements,
improving in that way the database for mapping and prediction of the geogenic radon potential.