Radon emanation from fresh, altered and disturbed granitic rock characterized by 14C-PMMA impregnation and autoradiography

Radon emanation from intact samples of fresh (“BG”), altered (“Fract”) and disturbed (“EDZ”) Finnish granitic rock from Kuru (Finland) and its dependence on humidity and rock structural factors was studied. The pore network of the rock was characterized by microscopy and impregnation with 14C-PMMA (polymethylmethacrylate) resin and autoradiography. The radon emanation factor was increasing linearly with the relative humidity. 14C-PMMA autoradiography of the altered zones and the EDZ indicated significant, mineral-specific increase of porosity and porosity gradients towards the fracture surfaces (Fract) and microcracks within the EDZ. For small samples in the cm-scale emanation was not diffusion, but source term controlled.