Phytoremediation of a metal contaminated area in Southern Spain

The EMIR-UCO is a multidisciplinary group including agronomists, botanists, soil scientists, plant physiologists, microbiologists and biochemists at the Agronomy and Forest Science High Technical School, University of Cordoba, involved since 1998 in research projects directed at developing and evaluating phytoremediation techniques for metal contaminated soils, initially related to the multicomponent metal contamination caused by the Aznalcollar (Southern Spain) toxic spill. The main objectives and related activities are to use plant and microorganisms as bioindicators of toxic metal contamination, to carry out botanical surveys directed at identifying and classifying autoctonous plant species growing in heavily contaminated areas, evaluating, by using field and greenhouse experiments, the tolerance to toxic metals in crops and wild species, developing either continuous and induced phytoextraction protocols adapted to both hyperaccumulators and high biomass producer plants, isolating and characterizing rizospheric bacteria and their effect on plant growth, tolerance to toxic metals and their ability to accumulate them, and characterizing plant responses to toxic metals at the molecular level, with special emphasis on metal adsorption, translocation and accumulation, and synthesis of stress metabolites (i.e. secondary metabolites, antioxidants). Plant model systems include crops (sunflower, maize, chickpea, thistle) and herbaceous wild species (Nerium oleander, Canna sativa, wild sunflower relatives, etc.). Most relevants results, so far obtained, will be described. This multidisciplinary approach has proved specially useful in building a greater understanding of the many and varied processes involved in phytoremediation techniques.