Identification of palaeo-seawater intrusion in groundwater using minor ions in a semi-confined aquifer of the Río de la Plata littoral (Argentina)

KRUSE EDUARDO; CAROL ELEONORA; SANTUCCI LUCIA

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 p. 1640 - 1648

0048-9697

The hydrochemistry of minor elements and traces such as bromide, lithium, strontium, uranium and selenium, togetherwith the chemical analysis ofmajor ions, has been used in the study of salinization process. This processBoccurs in a semi-confined aquifer that corresponds to a Pliocene?Pleistocene fluvial environment. The semi-confined aquifer is located in the littoral of the cities of Ensenada and Berisso, in the region of the middle Río de la Plata estuary, Argentina. Groundwater salinization was detected in the semi-confined aquifer in the coastal plain area, with salt contents that increase from the loess plain towards the river. The content of major ions that predominate in sea water (Cl−, Na+ and Mg2+), as well as the Cl−/Br− and U vs. Cl− ratios, demonstratesthat such salinization is related to seawater,which shows no correspondencewith estuarywater. In the salinized area, Li, Sr and Se enrichments occur, and are used as tracers of the average time that a substance remains in solutionin sea water in the aquifer. The study of suchminor ions togetherwith the geological evolution of the area made it possible to recognize that the saltwater in the semi-confined aquifer corresponds to a palaeo-intrusion ofsea water associated with the Pleistocene?Holocene ingressions caused by the climate changes occurring duringthe Quaternary.