Anais do XXXV Congresso Brasileiro de Ciência do Solo
SEQUENTIAL EXTRACTION OF COPPER IN BULK AND RHIZOSPHERE SOILS OF COMBRETUM LEPROSUM M. IN AN ABANDONED MINE SITE IN NE BRAZIL
FABIO PERLATTI(1); TIAGO OSÓRIO FERREIRA(2); XOSÉ LUIS OTERO(3); FRANCISCO RUIZ(2); 1 - DEPARTAMENTO NACIONAL DE PRODUÇÃO MINERAL; 2 - ESALQ/USP; 3 - UNIVERSIDAD DE SANTIAGO DE COMPOSTA/USC;
We evaluated the biogeochemical processes occurring in the rhizosphere of Combretum leprosum (Mufumbo); a plant native from the Brazilian semiarid; growing spontaneously in a highly Cu contaminated soil in an abandoned mine site in NE Brazil. The effect of these processes on copper mobility, toxicity, and the ability of this plant to be used as pioneer specie on restoration programmes were also assessed. Chemical properties (pH, % of TOC and % of TIC), and Cu sequential extraction were determined in both rhizosphere and bulk soil. The study findings show that the plant have greatly altered the physicochemical characteristics of the soil under the influence of their roots, by altering various soil components, affecting the biogeodynamic cycle of copper. The changes that occur in the rhizosphere affected copper dynamics mainly by decreasing the concentration of potentially bioavailable Cu evidenced by a significant reduction in the exchangeable and carbonate-associated Cu. Results also showed an increase in the Cu associated with amorphous Fe oxides, enhancing Cu immobilization and probably minimizing the risks of Cu toxicity and mobility in the rhizosphere. The biogeochemical processes observed in the rhizosphere of the studied specie seem to indicate that this plant may promote phytostabilization of Cu in their rhizosphere zone, and thus show desirable characteristics for use in phytoremediation programmes.
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