Potencial of macrophytes to remove arsenic and atrazine from water solution / Potencial de macrófitas para remoção de arsênio e atrazine em solução aquosa

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The potential of three aquatic plants: Azolla caroliniana, Salvinia minima and Lemna gibba was evaluated, in this study, in order to select plants to be used in phytoremediation of water polluted by arsenic (As) and atrazine. The experiments were carried out in a green house, during six days, using vases containing Hoagland solution ( of ionic force), in the following concentrations: 0,5; 2,5 and 5,0 mg L-1 of As and 0,01; 0,1; 1,0; 10,0 mg L-1 of atrazine. The three species showed an increase accumulation of arsenic, while there was an increase of arsenic concentration in solution. However, it was noticed a reduction in the fresh and dry mass production, when the plants were exposed to high concentrations of As. The plants demonstrated differences in the efficiency of removal of As from the solution. Azolla caroliniana, S. minima and L. gibba accumulated on average 0,130; 0,200 and 1,397 mg gMS-1 of As, respectively, when exposed to 5,0 mg L-1. In solution with low phosphate concentration, the plants removed more As, because the phosphate and As, in the arseniate form, compete for the same absorption sites. As greater the concentration of As in the L. gibba tissues was, the smaller the total chlorophyll and carothenoid synthesis was, found by the cloroses incidence. Also, L. gibba, showed reduction of the leaf sizes. However, the As in the leaves did not affect the synthesis of total chlorophyll and carothenoid in A. caroliniana. This specie presented purple leaves, containing high anthocyanin levels, which suggested a phosphate deficiency. Salvinia minima showed marginal necrosis, in flotation leaves and the plants were capable to reproduce, generating health daughter plants, free from any visual symptoms. In the atrazine study, an herbicide that blocks the photosynthesis process, the three species had a reduction on the fresh and dry mass, that caused their deaths. The clorosis and necrosis observed in the plants showed the sensitivity of the three species towards the herbicide. All plants showed low potential to remove atrazine from solution, when exposed to low concentrations of the herbicide. However, in the concentration of 10,0 mg L-1 of atrazine, which caused the plants deaths, L. gibba and A. caroliniana demonstrated a good potential to remove the herbicide from the solution (0,016 and 0,018 mg gMF-1, respectively). Probably, this potencial is related to adsorption of atrazine from the dead tissues. The percentage of As and atrazine removed from the solution, for the studied plants, reduced when the plants were exposed to higher concentrations of the pollutants. The use of these species in the remediation of aquatic environments was limited, which required more accurated studies. Of the three species, L. gibba was the only arsenic hyperaccumulator plant, while A. caroliniana, S. minima and L. gibba were not efficient to remove atrazine from the solution.

ASSUNTO(S)

fitorremediação atrazina arsenic botanica aplicada phytoremediation arsênio atrazine

ACESSO AO ARTIGO

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