Heavy metal content in Erica andevalensis:: An endemic plant from the extreme acidic environment of TiNto river and its soils

The Tinto River (Huelva, Spain) constitutes a complex and singular system characterized by extreme acidity and high concentrations of iron and other metals (Cu, Co, Mn, Zn, Pb, As) of its soils and waters. Traditional mining activity and the resulting intensive deforestation have eliminated its natural vegetation. Communities of the endemic Erica andevalensis colonize the fluvial terraces of the mining areas of the Tinto River, from drier to more humid soils, reaching its optimum in the proximity of rivers and streams. Concentrations of 22 (S, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Sr, Cr, Na, Mg, Al, Sc, Ti, Rb, Cd, Ba, Hg) elements have been determined for soils and E. andevalensis specimens at several points near the origin of the river. Erica andevalensis shows a remarkable capacity to survive with meager quantities of nutrients and an extraordinary tolerance to high concentrations of heavy metals. However, this heath does not show a lack of nutrients (Ca: 2012-5942 ppm; K: 223-3771 ppm; Mg: 883-2566 ppm) nor an excess of metals in its tissues (Fe: 73-514 ppm; Cu: 9-16 ppm; Co: ND-2 ppm). These abilities make E. andevalensis an ideal candidate for revegetation of mining areas and phytostabilization of heavy metal contaminated soils. These characteristics together with the exclusive extreme habitat on which E. andevalensis grows, make it possible to classify it as a metal bioindicator, e. g., for Cu.