Contribuicao para o estudo da contaminacao de solos por metais pesados Caso do cobre num regossolo psamitico

Potential contamination of groundwater was evaluated through soil samples from an unpolluted homogeneous area close to an inter municipal sanitary landfill. Samples were contaminated with several spike doses of copper, under different pH values, using batch reaction as well as continuous percolation tests. Several equilibrium models were tested for their ability to describe the retention of copper by the soil. The Freundlich model described successfully the relationship between the amount of metal retained by the soil and the concentration of metal in solution. Sequential extraction after batch experiments has shown that copper content increased in almost all soil fractions, specially in the "amorphous oxides and hydroxides". Preliminary percolation tests were conducted in soil columns, in order to obtain breakthrough curves and "aqua regia" extractions were performed to confirm the amount of metal actually retained in each soil column. In the dynamic system it was observed that copper retained in the soil phase was much higher than in the batch experiments for the same equilibrium liquid phase concentration. These results need to be confirmed under pH controlled conditions, as well as the simultaneous occurrence of adsorption and chemical reaction. In comparison with the batch system, sequential extraction after dynamic experiments has shown higher concentrations of copper in the fractions "exchange" and "amorphous oxides and hydroxides". Thus, probability of water contamination is larger with dynamic conditions, since copper retained in the "exchange" fraction has the smallest retention energy. However, as copper concentration in the "amorphous oxides and hydroxides" is always higher than in the remaining fractions, situations of unavailability of this metal in the soil might occur if iron recrystallization happensAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga