RADON: GEOINFORMATION FOR THE PLANNING OF URBAN – SUBURBAN REGIONS. THE CASE OF NAFPLION CITY, GREECE
Radon is trapped in the terrestrial cover as a transmutation product of natural radioactive elements. It is directly related to the geotectonic environment and the atmosphere contains traces of radon near the ground, as a result of emanations from soil and rocks, both of which contain minute quantities of radium; it also infiltrates into the ground and circulates in groundwater. Because naturally occurring radon gas has come to be recognised as a potentially serious health hazard, especially in the built environment, a radon and radiometric (α- and γ-radiation) survey was carried out in the urban and suburban region of Nafplion, using the same grid of 500 x 500 m that was used by other methods, i.e., urban geochemical and geophysical surveys. Radon was measured down to a soil depth of 50 cm, and at each site α- and γ-radiation measurements were taken. The survey results have shown that these concentrations are low compared to other regions of Greece. However, potential accumulations of radon in closed underground spaces cannot be excluded. The isoradon contours of these concentrations form anisotropy axes of main NW to NE and N-S direction related to geological-tectonic structures.