Uso de espécies florestais na fitorremediação do solo contaminado por cádmio.

Abstract

Cadmium (Cd) contamination of soils represents a potential risk to human and environmental health. The use of forest species as a metal phytoremediator can be an economically and ecologically sustainable choice when associated with silicate fertilization, which will alleviate metal toxicity to plants. In this sense, the study aimed to evaluate: the tolerance of two forest species (Casearia sylvestris Swartz and Machaerium aculeatum Raddi) cultivated in a soil contaminated by Cd and submitted to silicate adduction; bioaccumulation and distribution of Cd and Si, as well as changes in plant nutritional status. The experiment will be carried out in a greenhouse in a completely randomized design in a 2 x 2 factorial arrangement (two forest species: M. aculeatum and C. sylvestris; combined with 0.0 and 200.0 mg kg-1 Si). with three repetitions. The soil used in the experiment was collected at a depth of 0.0 - 0.2 m and characterized chemically and physically. The soils were weighed 9 kg for each pot. Soil contamination was induced with CdCl2.H2O above 10.0 mg kg. Subsequently, they were treated with Si as calcium silicate and then a seedling of each species was transplanted to each pot. The experiment was collected after four months of transplantation. The seedlings were collected and separated in shoots and roots; soil samples were also collected. Soils and plants were extracted and the contents of Cd and Si were determined; In the vegetal tissues the contents of N, P, K, Ca and Mg were determined. The results were submitted to descriptive statistical analysis, ANOVA (one way p <0.05) and Tukey test (p <0.05). The results showed that M. aculeatum presented better tolerance to Cd and when associated with Si obtained higher root biomass and better nutritional status, as well as Si influenced the translocation of Cd to shoot. Although Cd bioaccumulation was more significant in C. syvestris, its development was affected by biomass loss and poorer nutritional status. The distribution of Cd in both species presented the highest concentration in the root. Evaluating the best yield and biomass results, tolerance and nutritional status, M.aculeatum demonstrated potential as a phytostabilizer of cadmium contaminated soil.