Comportamento de mudas de espécies florestais nativas na fitorremediação de solo contaminado com zinco e cobre

Abstract

Phytoremediation is a technology of environmental cleanup with residues of anthropogenic origin. This technology uses the vegetables and their microbial rhizosphere to stabilize, extract, degrade, or votilization for various organic and inorganic pollutants. Native forest species join an acceptable visual characteristic to the recovery project, they are perennial and they request less cultural treatments, they produce matter excels of interest for several sections, being a drain of atmospheric CO 2. In the present work, we evaluated the behavior of cedro-rosa (Cedrela fissilis Vell. (Meliaceae) and ipê-roxo (Tabebuia impetiginosa (Mart.) Standl. (Bignoniaceae)) seedlings of these species were used in the phytoremediation of a polluted soil with zinc and copper. The seedlings were transplanted to pots containing 4,2 kg of a Yellow Latosol, sandy texture, which was contaminated whittle increasing doses of Zinc (0, 300, 400, 500, 2.500 mg kg-1) and Cooper (0, 60, 80, 100, 500 mg kg-1). Before adding the treatments the soil homogenized and sieved in a 0.5 mm sieve. Each pot was fertilized whittle the macronutrients N, P, K, Ca and S in the doses of 200, 300, 200, 129 e 61,5 mg kg-1, respectively, in the form of nitrate of ammonium (NH4NO3), phosphate of calcium (Ca(H2PO4 )2.H2O) and sulfate of potassium (K2SO4). To contaminate the soil, Zn and Cu were added as copper nitrate (Cu(NO 3)2.3H2O), zinc nitrate (Zn(NO3)2.6H2O) and zinc chloride (ZnCl2). The soil moisture was maintained near the field capacity, being daily corrected based on the weight of the total mass of the unit amostral. After 105 days the seedlings were collected, separated in roots and aerial part. They were drought in forced ventilation greenhouse 70 °C until constant weight. Was achieved after that the material was ground and taken to the laboratory where they were mineralized of by a nitric-percloric digestion (4:1 v/v). The contents of zinc and copper were measured by atomic absorption. The results of biomass production suggested that the cedro-rosa was more tolerant to the zinc than the ipê-roxo. Both species allocated more carbon in the root to the detriment of the aerial part. The cedro-rosa absorbed larger contents of zinc demonstrating accumulative behavior while the ipê-roxo showing an indicative behavior. In the ipê-roxo were the largest contents of zinc. In the copper treatment the ipê-roxo was more tolerant than the cedro-rosa. The root was the organ of copper storage for both species. The cedro-rosa absorbed larger copper contents with accumulative behavior while the ipê-roxo had an indicative behavior. It could be seen that both species possess use potential in the phytostabilization and induced phytoextraction of zinc and copper in polluted soils.