ABSTRACT
Sulfentrazone is amongst the most widely used herbicides for treating the main crops in the State of São Paulo, Brazil, but few studies are available on the biotransformation of this compound in Brazilian soils. Soil samples of Rhodic Hapludox soil were supplemented with sulfentrazone (0.7 µg active ingredient (a.i.) g-1 soil) and maintained at 27ºC. The soil moisture content was corrected to 30, 70 or 100 percent water holding capacity (WHC) and maintained constant until the end of the experimental period. Herbicide-free soil samples were used as controls. Another experiment was carried out using soil samples maintained at a constant moisture content of 70 percent WHC, supplemented or otherwise with the herbicide, and submitted to different temperatures of 15, 30 and 40º C. In both experiments, aliquots were removed after various incubation periods for the quantitative analysis of sulfentrazone residues by gas chromatography. Herbicide-degrading microorganisms were isolated and identified. After 120 days a significant effect on herbicide degradation was observed for the factor of temperature, degradation being higher at 30 and 40º C. A half-life of 91.6 days was estimated at 27º C and 70 percent WHC. The soil moisture content did not significantly affect sulfentrazone degradation and the microorganisms identified as potential sulfentrazone degraders were Nocardia brasiliensis and Penicillium sp. The present study enhanced the prospects for future studies on the bio-prospecting for microbial populations related to the degradation of sulfentrazone, and may also contribute to the development of strategies for the bioremediation of sulfentrazone-polluted soils.
Subject(s)
Biodegradation, Environmental , Herbicides/analysis , Herbicides/isolation & purification , Nocardia/isolation & purification , Penicillium/isolation & purification , Soil , Soil Moisture , Sulfides/analysis , Chromatography, Gas , Methods , Population , Sampling Studies , MethodsABSTRACT
Sulfentrazone is amongst the most widely used herbicides for treating the main crops in the State of São Paulo, Brazil, but few studies are available on the biotransformation of this compound in Brazilian soils. Soil samples of Rhodic Hapludox soil were supplemented with sulfentrazone (0.7 µg active ingredient (a.i.) g(-1) soil) and maintained at 27°C. The soil moisture content was corrected to 30, 70 or 100 % water holding capacity (WHC) and maintained constant until the end of the experimental period. Herbicide-free soil samples were used as controls. Another experiment was carried out using soil samples maintained at a constant moisture content of 70% WHC, supplemented or otherwise with the herbicide, and submitted to different temperatures of 15, 30 and 40° C. In both experiments, aliquots were removed after various incubation periods for the quantitative analysis of sulfentrazone residues by gas chromatography. Herbicide-degrading microorganisms were isolated and identified. After 120 days a significant effect on herbicide degradation was observed for the factor of temperature, degradation being higher at 30 and 40° C. A half-life of 91.6 days was estimated at 27° C and 70 % WHC. The soil moisture content did not significantly affect sulfentrazone degradation and the microorganisms identified as potential sulfentrazone degraders were Nocardia brasiliensis and Penicillium sp. The present study enhanced the prospects for future studies on the bio-prospecting for microbial populations related to the degradation of sulfentrazone, and may also contribute to the development of strategies for the bioremediation of sulfentrazone-polluted soils.
ABSTRACT
Avaliou-se a biodegradação de Glifosato em amostras de dois solos brasileiros, ambos com e sem histórico de uso prévio do herbicida. Aplicou-se o Glifosato em 75 g de cada amostra de solo (tres repetições) na dosagem recomendada para condição de campo (2,16 kg i.a/ha). A biodegradação foi avaliada monitorando-se a liberação de CO2 pelos microorganismos no período de 32 dias. Durante esse período foram quantificados os resíduos de Glifosato e seu principal metabólito por meio de extração, seguida de análise por Cromatografia a Líquido de Alta Eficiência. Os resultados mostraram que o Glifosato foi degradado pelos microorganismos do solo, com formação de seu metabólito ácido aminometilfosfônico (AMPA). A degradação mostrou-se ligeiramente superior em Argissolo que em Latossolo
Subject(s)
Agricultural Zones , Biodegradation, Environmental , HerbicidesABSTRACT
Efetuou-se avaliaçäo preliminar de pesticidasaplicados em plantaçöes de eucaliptos e coqueiros no nordeste brasileiro quanto ao risco de contaminaçäo de águas superficiais e subterrâneas. Para tanto, foram utilizados os critérios sugeridos pela Agência de Proteçäo Ambiental dos Estados Unidos (USA), o índice "Growndwater Ubiquity Score" (GUS) e o método de Goss. Os pesticidas Tetradifon, Triclorfon, alfa-Endosulfan, B-Endosulfan, Sulfato de Endosulfan e Glifosato apresentaram potencial de contaminaçäo das águas que exige monitoramento. Segundo os critérios avaliados neste estudo, os demais pesticidas investigados näo apresentarem risco de contaminaçäo
