Caracterización hidroquímica e isotópica del acuífero kárstico carbonatado de la Sierra del Aramo (Asturias, NO España)

Abstract

Despite the Aramo Range carbonate karst aquifer (Serpukhovian-Moscovian) supplies water to 22% of Asturias region (NW Spain) population, no detailed hydrological studies are available. Hydrochemical and isotopic characterisation has been performed based on sample analysis from March 2017 to May 2018, for future study of the relationship between geology, water chemistry and hydrodynamic behaviour. Obtained parameters values include: EC, pH, T, ORP, major and minor ion concentration, concentration in B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sn, Sb, Ba, Hg, Tl, Pb and U, and δ2H, δ 18O and δ 87 Sr. Hydrochemical characteristics of the water discharge matches the aquifer geological nature, varying seasonally. Resulting values unravel a quite relevant water-rock interaction. In this regard, As and Sr con- centrations reach 1 μg/l and 600 μg/l, respectively, with a N-S positive gradient, during minimum discharge flow periods, which might relate to the Sr, Cu, Ni and Co mineralised limestone. As and Sr concentrations might be relevant for health risk (WHO, 2017; USEPA, 2014), therefore regular monitoring is recommended. δ2H and δ18O are depleted relative to the nearest reference stations (Díaz-Teijeiro, 2009), which might relate to a higher recharge altitude. δ 87Sr values match a Carboniferous limestone.