Avaliação do potencial de Moringa oleifera L. na fitorremediação de águas contaminadas pelo herbicida atrazina

Abstract

Phytoremediation is a low-cost emerging technique, which uses plants to remove, transform or stabilize soil, air and water contaminants. Some plants, counted as good candidates for soil and water remediation, have been evaluated regarding the genetics and biochemistry processes involved in the capitation, transport and storage of the pollutants. Moringa oleifera presents some of the important characteristics in the selection of plant species for phytoremediation. Among them, stand out its coagulating/floculating properties, good adaptability to Ceará state's climatic conditions, fast growth rate and high resistance to diseases. Thus, the present work aims to evaluate the potential of M. oleifera for the phytoremediation of water contaminated by atrazine, an herbicide widely used in the world. For this, M. oleifera plants were put in contact with water artificially contaminated by atrazine in the 0.2, 1, 2 and 20 mg/L concentrations. The phytoremediation potential was evaluated through vegetal growth parameters, enzymatic activities and the capacity to reduce the atrazine concentration in water samples. The results demonstrate that the plants were intolerant to the 2 and 20 mg/L atrazine dosages. However, the plants submitted to the 0.2 and 1 mg/L dosages could survive until the end of the experiment, even though they presented evidence of phytotoxicity. The measure of enzymatic activity related to oxidative stress proved that treated plant's leaves and roots presented distinct profile of molecules. Overall, were observed a significant increase of peroxidase enzymes (POX and APX), especially in roots of plants submitted to atrazine treatment. The evaluation of the levels of atrazine in the hydroponic medium showed that within two days of treatment, the moringa plants reduced atrazine levels by 43%. After 10 days of treatment, the degradation rate was 89%. The results indicate that M. oleifera is a species with great potential for phytoremediation of environments contaminated with atrazine and other compounds of environmental relevance.