Fitorremediação de pesticidas utilizados em lavouras de arroz através do cultivo hidropônico de alface (Lactuca sativa l.)

Abstract

Pesticides are synthetic compounds that enable an increased production and quality of agricultural products by reducing losses caused by unwanted organisms. However, they can generate a gradual environmental problem due to their toxicity. Pesticide residues and their metabolites have often been found in groundwater and surface. Thus, the contamination of water bodies may directly or indirectly affect human health and the ecosystem integrity by inducing a significant threat to aquatic environments and drinking water resources. The decontamination of water contaminated by pesticides is expensive and involves great expenditure of energy. The phytoremediation (the use of plants to decontaminate xenobiotics) has gained popularity as a low cost, environmentally friendly and efficient in situ technology for a variety of pollutants and, among them, many pesticides. The present study evaluated the potential for phytoremediation of lettuce to water containing a mixture of pesticides quinclorac, 2,4- D, clomazone, propanil and tebuconazole concentration of 50 μg/L through hydroponics. Therefore, a multirresidue method for determination of pesticides cited by high performance liquid chromatography, with diode array detection (HPLC-DAD), in drinking water and hydroponic medium was developed and validated. The method has proven effective, reliable with good sensitivity and reproducibility for determining the compounds of interest. The method provides further flexibility to add new pesticide and/or its degradation products. For the evaluation of phytoremediation lettuce seedlings were grown and after ten days, the culture media was fortified with the x pesticides under study. Water samples were collected from cultivation on fortification, on the 7th and 14th days after treatment. It was observed a significant decrease in concentrations of quinclorac, tebuconazole, clomazone and 2,4-D, and the best results were obtained after seven days for the first two compounds and for the past fourteen days, respectively. This study shows the potential of hydroponic cultivation of lettuce for phytoremediation of pesticides in water.