RESUMOO glifosato é um herbicida sistêmico, pós-emergente, não seletivo do grupo dos organofosforados, sendo amplamente usado em pomares de macieira no sul do Brasil, podendo causar consequências negativas para microrganismos benéficos do solo. O objetivo deste trabalho foi avaliar a capacidade de biodegradação do glifosato pela microbiota de solos de pomares de macieira, com diferentes históricos de aplicação do produto. Para isso, amostras de solos da região de Vacaria, RS, foram utilizadas, cuja biodegradação do glifosato foi avaliada monitorando a liberação de CO 2 pelos microrganismos durante 32 dias, bem como quantificando os resíduos de glifosato e seu metabólito, o ácido aminometilfosfônico (AMPA), no início e no final do período pela extração seguida de análise por cromatografia líquida de alta eficiência. Os resultados evidenciaram que houve degradação do glifosato pelos microrganismos edáficos durante o período avaliado com formação do metabólito AMPA. O glifosato diminuiu o número de bactérias do solo, porém favoreceu o aumento da atividade microbiana. As bactérias presentes nos solos com histórico de menor tempo de aplicação do herbicida apresentaram maior capacidade de degradação do produto, quando comparadas àquelas existentes em solos com maior período de aplicação de glifosato.
Biodiesel is an alternative energy source that has a high biodegradability potential and low toxicity, contributing to ecosystem impact reductions. The aim of this study was to determine, by the natural attenuation technique, the microbial activity of two soils: one clayey (CLA) and the other sandy (SAN), contaminated with different concentrations of biodiesel blended with diesel (B0, B5, B20 and B100) simulating a surface spill. The respirometry, fluorescein diacetate (FDA) hydrolysis and cultivable heterotrophic bacteria and actinobacteria count techniques were used to determine the microbial activity in the different microcosms at up to 48 days of incubation. For the respiration activity, the CLA soil was most active at all mixed fuel concentrations (B0, B5, B20 and B100), as compared to the SAN. Furthermore, the biodiesel addition to the two soil types contributed to the microbial activity increase, and higher CO 2 release values were found in the B20 and B100. For the FDA activity, it was found that the CLA soil showed higher activity at the B5 and B20 concentrations, and heterotrophic count showed a tendency towards a CFU g-1 decrease as the incubation time increased. This indicates that the CLA soil, due to a higher amount of nutrients, clay, organic matter and CEC, was associated with the addition of biodiesel and showed higher microbial activity. The results obtained in this study contribute to future studies of surface contamination by different mixtures of diesel/biodiesel in soils with similar physical and chemical characteristics.
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