Caracterización geoquímica de balsas mineras de la Faja Pirítica Ibérica

Abstract

In this work, the first data on trace element geochemistry (including the majority of heavy metals of interest in environmental geochemistry) are presented. These data have been performed in tailings belonging to three mining ponds located in the Iberian Faja Pirítica. The results indicate the existence of extensive concentration ranges for different elements, not only between different ponds, but also sometimes in the same pond, as a function of depth. By means of a principal component analysis, four groups of samples have been delimited inside the mentioned variability: 1) group N, homogeneous (La Nava-Nerva pond); 2) group MC, less homogeneous, but akin to the former (Mina Concepción pond); 3) and 4), groups MR-I and MR-II, for the non water-saturated and water-saturated zones, respectively, of the Monte Romero pond. The two former groups display a more ‘lithologic’ or ‘barren’ character, whereas the two latter ones display, on the contrary, a more ‘metalogenic’ character, with higher concentrations especially of As, Ba, Zn and Sb. These results show that very disparate conditions exist for the different mining ponds from an environmental risk point of view, and so it is mandatory that, more in-depth, geochemical-mineralogical studies, are performed before a correct evaluation of the environmental risk can be attained.