Factors affecting the radon ( 222 Rn) emanation from aquifer rock materials: implications for radiological and groundwater tracer studies.

VITAL, MELANIE; GRONDONA, S.; DIMOVA, N.; MARTINEZ, DANIEL EMILIO

Bariloche

Congreso; VI Reunión Argentina de Geoquímica de la Superficie; 2022

Laboratory sediment equilibration experiments with various sediment and rocks materials, including sand, granitic, gneiss and loess deposits that constitute the Pampeano Aquifer (PA) in the Buenos Aires Province, Argentina, were applied to examine the factors affecting the magnitude of radon 222 Rn emanation. A decreasing linear relation was found between radon emanation and effective diameter (d e ) for particles with a d e under 2 mm in the tested PA sediment and rock materials. Based on these results, loess sediments with the smallest particle size and the largest particle surface area showed the highest radon emanation. This strongly suggests that these two parameters are the mostparameters that govern the magnitude of the radon diffusive fluxes in the PA. On the other hand, the PA basement rocks, which are primarily granite and gneiss, showed a production rate of radon of 8.1 Bq.m 2 h r-1 and 13.2 Bq.m 2 h r-1 respectively which is two orders of magnitude higher than loess sediments (0.3 ± 0.1 Bq.m 2 h r-1 ) owning to the higher natural content of radon’s parent isotopes from the 238 U natural decay series.