Glyphosate, Other Herbicides, And Transformation Products In Midwestern Streams, 2002

The use of glyphosate has increased rapidly, and there is limited understanding of its environmental fate. The objective of this study was to document the occurrence of glyphosate and the transformation product aminomethylphosphonic acid (AMPA) in Midwestern streams and to compare their occurrence with that of more commonly measured herbicides such as acetochlor, atrazine, and metolachlor. Water samples were collected at sites on 51 streams in nine Midwestern states in 2002 during three runoff events: after the application of pre-emergence herbicides, after the application of post-emergence herbicides, and during harvest season. All samples were analyzed for glyphosate and 20 other herbicides using gas chromatography/mass spectrometry or high performance liquid chromatography/mass spectrometry. The frequency of glyphosate and AMPA detection, range of concentrations in runoff samples, and ratios of AMPA to glyphosate concentrations did not vary throughout the growing season as substantially as for other herbicides like atrazine, probably because of different seasonal use patterns. Glyphosate was detected at or above 0.1 μg/l in 35 percent of pre-emergence, 40 percent of post-emergence, and 31 percent of harvest season samples, with a maximum concentration of 8.7 μg/l. AMPA was detected at or above 0.1 μg/l in 53 percent of pre-emergence, 83 percent of post-emergence, and 73 percent of harvest season samples, with a maximum concentration of 3.6 μg/l. Glyphosate was not detected at a concentration at or above the U.S. Environmental Protection Agency’s maximum contamination level (MCL) of 700 μg/l in any sample. Atrazine was detected at or above 0.1 μg/l in 94 percent of pre-emergence, 96 percent of postemergence, and 57 percent of harvest season samples, with a maximum concentration of 55 μg/l. Atrazine was detected at or above its MCL (3 μg/l) in 57 percent of pre-emergence and 33 percent of postemergence samples

Risco de contaminação das águas de superfície e subterrâneas por agrotóxicos recomendados para a cultura do arroz irrigado

A produção agrícola geralmente está associada ao uso de agrotóxicos. Suas características físico-químicas, condições do solo e do ambiente determinam seu destino, assim como o seu potencial de contaminação dos mananciais hídricos. Com o intuito de prever a contaminação do ambiente por agrotóxicos, critérios e modelos matemáticos são utilizados para avaliar o risco de contaminação das águas subterrâneas e superficiais. Diante do exposto, este trabalho teve por objetivo estimar a probabilidade de contaminação de águas subterrâneas e superficiais por agrotóxicos, baseado nas suas características físico-químicas, com auxílio de modelos e parâmetros matemáticos preexistentes. Para análise do risco de contaminação de águas superficiais, foi utilizado o método de Goss, o qual é dividido em dois grupos: potencial de transporte de agrotóxicos dissolvidos em água e adsorvido ao sedimento. Os critérios utilizados para avaliar o potencial de lixiviação foram os sugeridos pela Agência de Proteção Ambiental dos EUA e pelo Índice de GUS. Os resultados obtidos neste trabalho permitem concluir que o uso de modelos de predição do comportamento de agrotóxicos é útil para se obter uma estimativa do risco de contaminação ambiental, pois alguns resultados de monitoramentos confirmam a tendência do comportamento de certos agrotóxicos no ambiente.Agricultural production is generally associated with the use of pesticides, their physicochemical characteristics, soil conditions and the environment will determine their fate, as well as the potential for contamination of water bodies. In order to predict environmental contamination by pesticides, parameters and mathematical models are utilized to assess the risk of contamination of groundwater and surface water. For this reason, the objective of this study was estimate the probability of contamination of groundwater and surface waters by pesticides based on their physicochemical characteristics with the aid of preexisting mathematical models and parameters. To analyze the risk of surface water contamination, the Goss method was used, which as composed by two groups: pesticide potential transport dissolved in water and adsorbed to the sediment. The parameter used to evaluate the leaching potential were those suggested by the US Environmental Protection Agency (EPA) and the GUS Index. The results obtained allow to conclude that the use of models to predict the behavior of pesticides is useful to obtain an estimate of the risk of environmental contamination, as some monitoring results confirm the tendency of the behavior of certain products into the environment