Revista Chilena de Historia Natural (Jun 2008)
Acumulación de cobre en una comunidad vegetal afectada por contaminación minera en el valle de Puchuncaví, Chile central Copper accumulation in a plant community affected by mining contamination in Puchuncaví valley, central Chile
Abstract
Las especies hiperacumuladoras son capaces de acumular más de 1.000 mg kg-1 de metal en su biomasa aérea y son útiles en procesos de fitoextracción de metales en suelos contaminados por actividades mineras. Con el fin de identificar especies hiperacumuladoras representativas de las condiciones chilenas, se realizó una prospección dentro de la diversidad vegetal en el área afectada por las emisiones de la Fundición Ventanas (90-900 mg kg-1 de Cu total en suelos), así como en un área cercana a una pila de escorias de fundición (500-3.000 mg kg-1 de Cu total en suelos). Se determinaron las concentraciones de Cu en la biomasa aérea de las plantas. Los resultados indican que dentro de la diversidad del sitio existen al menos veintidós especies pseudometalofitas, es decir, ecotipos de especies comunes que son capaces de tolerar concentraciones de cobre en el suelo que para una planta normal serían tóxicas. Las especies fueron clasificadas según su concentración de cobre y mostraron en su mayoría media (200-600 mg kg-1) o baja (Hyperaccumulator plants species are capable of accumulating more than 1,000 mg Cu kg-1 in their shoots and are useful for metal phytoextraction in soils contaminated by mining activities. To identify the hyperaccumulator plants representative of the Chilean conditions, we carried out a survey of plant diversity in the área affected by the emissions of the Ventanas smelter (90-900 mg kg-1 of total Cu in soils) and in a nearby área cióse to a smelter slug pile (500-3,000 mg kg-1 of total Cu in soils). Copper concentrations in the shoots of the studied plants were determined. Results indicate that there were at least twenty-two pseudometallophyte species, i.e., ecotypes of common species capable to tolérate concentrations of Cu in the soil that would be toxic for a normal plant. The species were classified by their copper accumulation and nearly all exhibited médium (200-600 mg kg-1) or low (< 200 mg kg-1) accumulation of copper. The species with the highest accumulation of copper was Oenothera affinis (614 mg kg-1). However, no hyperaccumulator species were found. Oenothera affinis could be considered as a good candidate for remediation initiatives in Chile, because it is a native perennial herb, it is drought resistant, it is easy to propágate, and that it produces a large biomass. However, it is still required to verify that there was no overestimation of Cu concentrations in the plants due to attachment of particles onto the trichomes. In addition, two new samplings were carried out later in the growing season, for Argemone subfusiformis and Oenothera affinis. There was a decrease in the concentration of Cu in the shoots with the advance of the season caused by the development of structures with low Cu accumulation (flowers, fruits, and summer leaves) during the reproductive stage and the loss of Cu-rich biomass during the senescence. Moreover, this last sampling suggests that there was possibly a certain re-translocation of Cu into the subterranean structures during the senescence for O. affinis.
