Avaliação do potencial de espécies de eucalipto na remediação de áreas contaminadas com metais pesados

Abstract

With the increase of environmental pollution and soil contamination as a result, it is necessary to study the interaction between pollutants and the environment, and strategies to minimize and or recovery from the environment problems generated. For remediation of soils contaminated with heavy metals it is possible to use fitoremediation, which is the usage of plants in order to clean or contain pollutants, through techniques such as fitoextraction and fitostabilization. In the strategy of fitoestabilization agents with potential to reduce the availability and mobility of toxic elements to the soil are applied, reducing its toxicity. One of the basic requirements for the success of any technique of revegetation is to find plants tolerant to contaminants. This study aimed to evaluate the use of Eucalyptus urophylla and Eucalyptus saligna in the reclamation of soil contaminated with cadmium, zinc, manganese, and lead. The experiment was conducted in a greenhouse in the Universidade Federal Rural do Rio de Janeiro. It was used a substrate contaminated with high levels of Cd, Zn, Mn, and Pb, from the ore patio of CSN in Itaguaí port, Rio de Janeiro. The substrate was treated with the two following inertizant agents: an alkaline industrial residue (slag of aciaria), applied in two doses 4% and 6%; and a residue with a high iron oxide content (russeting) that acted as adsorbent, applied in a single dosage of 1%. After planting the eucalypt seedlings, samples of the substrate were taken in each unit test for determining the studied element concentrations in the different soil chemical fractions. It was found that the non-treated substrate had a high metal content in the hydro soluble fraction. The treatments resulted in a reduction of Cd level in solution, with the increase of more stable and non bio available forms. The lowest dose of slag from aciaria applied was sufficient for decreasing the levels of cadmium and zinc in the solution. This effect is evidenced by the development of the plants, where it was observed that the addition of the inertizants favored a better development of eucalyptus, and the largest dose of slag resulted in greatest development of Eucalyptus urophylla. Eucalyptus saligna did not show differences neither in the plants height nor diameter, in the various dosages of aciaria slag.