EDAFOLOGÍA, VOL 13. (2), PP 103-116 2006
AVALIAÇÃO DA ESTRATÉGIA DE IMOBILIZAÇÃO QUÍMICA EM SOLOS CONTAMINADOS
COM ZINCO PROVENIENTE DE LODO DE ESGOTO
ALCANTARA, A.M; AMARAL SOBRINHO, N.M.B.(1,3); OLIVEIRA,
C.(1) & MAZUR, N.(1,4)
1Departamento de Solos da Universidade Federal Rural do Rio de Janeiro (UFRRJ).
CEP 23890 000 Seropédica (RJ), Brasil 3Bolsista do CNPq 4Autor correspondente
The use of the sewage sludge’s in the agriculture can be limited by the presence of heavy metals, that they can cause contamination in the soils, in the aquifers and in the plants. This research had for objective: (i) to verify the chemical immobilization of Zn, Cd and Pb in soils treated with sewage sludge with high concentration of those heavy metals using immobilization agents and her stability with the timeIn a sewage sludge, produced in Rio de Janeiro, was added 6400 mg.kg -1 of Pb and 8000 mg kg 1 of Zn. After 20 days of incubation the enriched sludge was used for installation of experiments in samples of two types of soils: Yellow Red Latossol (LV) and Yellow Red Podzolic (PV). In laboratory, the samples of the soils were incubated with amount equivalent to 60 t ha 1 of the enriched sewage sludge. After 4 years and six months of contact soil sludge was settled, in laboratory, an experiment in plastic pots containing 400 g of the soils LV and LV with the enriched sludge and the following treatments: soil sludge; soil sludge + KH2PO4; soil sludge + CaCO3 and soil sludge + 0,07 moles L 1 FeCl3.6H2O + EDTA. Periodically, samples were removed for simple extractions with water, NaNO3, acetic acid and DTPA. With the tenors of Zn and Pb obtained in the extractions was estimated, through the differences in the amounts extracted, chemical forms of Zn and Pb. At 40 days of cultivation it was collected roots and aerial part and he/she was determined the production of dry matter and tenors of Zn and Pb. It was observed that the addition CaCO3 allowed chemical immobilization of Zn and Pb for the association of this with fractions chemistries more stability. The FeCl3 6H2O + EDTA caused dissolution of compounds of Zn and Pb and dessorção of these elements complexa- dos for functional groups of surface. The KH2PO4 didn't alter the distribution of Zn, Cd and Pb in the dif- ferent forms chemistries in the soils. With the time of incubation, in the soil LV, CaCO3 and KH2PO4 caused association of the zinc the compounds of Fe and Mn more crystalline and composed organic more stables, decreasing the availability. The availability of Pb, however, it increased in all of the treatments. The pr duction of dry matter of the aerial part, root and total was not affected significantly by the application of CaCO3 and KH2PO4. The addition of FeCl3 6H2O + EDTA affected significantly this parameter.
Key words: zinc, cadmium, lead contamination, soils.