GEOLOGICAL BASEMENT CONTROL ON 222RN ACCUMULATION AS AN INPUT FUNCTION FOR HYDROGEOLOGICAL SYSTEMS ON A LOESS AQUIFER, ARGENTINA.

VITAL, MELANIE; MARTINEZ, DANIEL EMILIO; GRONDONA, S.I.; LONDOÑO, MAURICIO QUIROZ; DONNA, FLAVIA; GILLES MORVAN

CATENA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020

0341-8162

In this study, theThe activity of 222 Rn of the groundwater was measured in different wells in thePampeano aquifer in southeastern Buenos Aires to assess the influencehow of thehydrogeological characteristics of the study area, which involves type and depth of bedrock,aquifer mineralogy and residence time along flowpaths, influences on 222 Rn contents. Watersamples, as well as sediment samples, were collected in multilevel piezometers in differentsites locations of the Buenos Aires province for the determination of stable isotopes, 222 Rnconcentrations and mineralogical analyses. The identification of uranium-bearing minerals inthe sediments was carried out with a scanning electron microscope allowing identifying zirconand monazite. The 222 Rn was determined with a RAD7 detector, showing a range of activitiesfrom 3.7 to 14 Bq/L. The results showed a relation between the 222 Rn activity, the depth of thewells, and the proximity of the Precambrian basement. The activity of 222 Rn increases linearlywith increasing depth at a rate of 0.08 Bq.l -1 .m -1 . However, at the same depth theconcentration of 222 Rn in wells near the Precambrian basement showed to be three timeshigher than the concentrations in the wells that have a Paleozoic basement, clearly showingthat the presence of gratinoids rocks results in higher concentrations of radon.