BECAS
ECHEGOYEN Cecilia Vanina
artículos
Título:
Use of radon-222 to assess the groundwater inflow in a phreatic lake of a dune field (San Luis, Argentine)
Autor/es:
ECHEGOYEN, CECILIA V.; LECOMTE, KARINA L.; CAMPODONICO, VERENA AGUSTINA; YACIUK, PABLO AGUSTIN; JOBBÁGY, ESTEBAN; HEIDER, GUILLERMO; SEPÚLVEDA, LAURA DANIELA; PASQUINI, ANDREA INÉS; DE MICCO, GEORGINA; BOHÉ, ANA ESTER
Revista:
BOLETIN GEOLOGICO Y MINERO
Editorial:
IGME
Referencias:
Lugar: Madrid; Año: 2021 vol. 132 p. 99 - 106
ISSN:
0366-0176
Resumen:
In the southeastern portion of San Luis Province (33°53´10´´-34°19´00´´ S and 65°42´00´´-65°20´00´´ W), the sand dune landscape hosts a lacustrine system with more than 200 water bodies, where the water table reaches the surface and fills the deepest depressions. The aim of this work is to analyze surface-groundwater interactions using the radioactive isotope radon-222 (222Rn) in a lake known as ?Los Pocitos?. During September 2017, in situ 222Rn determinations were performed in the air; in the water/sediment interface and in surface waters at 6 sampling stations, as well as in 4 groundwater samples collected in the dune and the lake mudflat using the RAD-7 equipment (Durridge Co.). Surface waters are of the HCO3- - Na+ - K+ type, with mean pH and electrical conductivity in Lake Los Pocitos of 8.7 and 1232 µS cm-1, respectively, whereas groundwaters are of the HCO3- - Ca+2 type, with variable pH and electrical conductivity values. In the northern portion of the lake, concentrations of 222Rn in surface water were ~ 70 Bq m-3, one order of magnitude greater than those of the southern sector, which registered values < 5 Bq m-3. By means of a 222Rn mass balance model it was possible to determine that the groundwater discharge occurs in the northern sector, with an inflow rate discharge of about 185.3 ± 39.1 m3 d-1, whereas in the southern sector, an outflow from the lake to surrounding aquifers can be detected. The intense groundwater inflow into these lakes may explain their relatively low salinity under a semiarid climate in which evaporation exceeds by far direct rainfall inputs.