On the Sources of Salinity in Groundwater under Plain Areas. Insights from δ18O, δ2H and Hydrochemistry in the Azul River Basin, Argentina

  1. Zabala , Mª Emilia
  2. Manzano Arellano, María del Sol 1
  3. Varni , Marcelo
  4. Weinzettel, Pablo
  1. 1 Universidad Politécnica de Cartagena
    info

    Universidad Politécnica de Cartagena

    Cartagena, España

    ROR https://ror.org/02k5kx966

Libro:
Isotopes in hydrology, marine ecosystems and climate change studies : proceedings of the International Symposium held in Monaco

Editorial: International Atomic Energy Agency (IAEA)

ISBN: 978-92-0-135610-9

Año de publicación: 2013

Páginas: 287-294

Tipo: Capítulo de Libro

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Resumen

The Azul River basin, with some 6200 km2, is located in the plains of Buenos Aires Province, Argentina. The Azul River flows along 160 km from the Tandilia Range, in the SW, to the Channel 11, in the NE. Average annual precipitation is 1005 mm (1988-2000); mean reference evapotranspiration is 1090 mm. The geology consists of Miocene to recent sediments, mostly sands and silts with some clay and calcrete layers, overlying crystalline rocks and marine sediments. The water table is shallow and groundwater in the aquifer upper 30 m displays an increasing salinity from SW to NE. The previous hypothesis to explain the salinity was infiltration of evapo-concentrated surface water, as the small soil slope in the northern basin (< 0.2%) induces rainfall accumulation in lowlands, where water evaporates prior to infiltration. But recent chemical and isotopic data reveal two salinity sources: evaporation of recent recharge water, and mixing with old saline groundwater of yet unknown origin. (author)