Characterization of the Salinisation Processes in Aquifers Using Boron Isotopes; Application to South-Eastern Spain
2008
Morell Evangelista, Ignacio | Pulido Bosch, Antonio | Sánchez-Martos, Francisco | Vallejos, Angela | Daniele, Linda | Molina, Luis | Calaforra, José María | Roig, Antoni Francesc | Renau, Alejandra
Use of δ¹¹B provides a solid tool for discriminating hydrogeochemical processes in complex coastal aquifers. Its efficiency increases markedly when it is applied along with other major or minor constituents. Nevertheless, various factors may affect its interpretation: the presence of clays, which favour adsorption and desorption, the influence of wastewaters, and even the presence of geothermalism. The δ¹¹B has been applied to the study of a series of aquifers in south-eastern Spain: Castell de Ferro (Granada), Campo de Dalías, Lower Andarax and Sorbas (Almería), all of which are complex and heterogeneous. The results obtained demonstrate that the concentration of Br, the SO₄/Cl and Cl/Br ratios are good indicators of marine intrusion. Inland some negative values of δ¹¹B (-16.7 and -8.1[per thousand]) are related to a geothermal influence (34.8 and 51.5°C). The boron solubility is directly related to temperature favours boron mobilization, even from the associated metapelitic deposits. The difference in the boron isotope content in two carbonate units must be caused by the different composition of the carbonate rocks, as well as a long residence time.
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