HYDRODYNAMIC AND HYDROCHEMISTRY OF WET MEADOWS AND SHALLOW LAKES IN AREAS OF THE PATAGONIAN BASALTIC PLATEAUS, ARGENTINA

MELENDI, EDOARDO; TANJAL CAROLINA; BORZI GUIDO; RAIGEMBORN MARIA SOL; CAROL ELEONORA

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020

0048-9697

Abstract: Extra-Andean Patagonia, located in the south end of SouthAmerica, is a wide arid region where the basaltic plateau landscapedominates. Associated with the basaltic plateaus, wet meadows and shallowlakes make up environments of relevance due to the ecosystemic servicesthey provide. The aim of this work was to define the processes andfactors that condition the hydrodynamics and hydrogeochemistry of wetmeadows and shallow lakes in a sector of the Patagonian plateau basalts.For this, detailed geological and geomorphological studies were carriedout and water was sampled at 29 points for the analysis of major ionsand, in some samples, stable isotopes of the water molecule. Values ofδ18O and δ2H similar to the local meteoric line in the water of wetmeadows indicate that rainwater quickly infiltrates through the fracturesof the basaltic plateaus and stores in the underlying sediments.Groundwater discharge occurs in the scarp zone due to changes in sedimentpermeability. The weathering of silicates in basalts, ion exchange in thesediment clays, and the dissolution of soluble salts provided by the dustcontrol water chemistry of this wetland. Water from wet meadows drainsinto saline endorheic basins of sodium chloride composition where theisotopic signal is indicative of evaporation percentages close to 95%.The high evaporation rates cause the precipitation of evaporitic salts atthe edges of shallow lakes with carbonate, sulfate, and chloride speciescontrolled by the dominance of sodium in the water.