ESTUDO DA LIXIVIAÇÃO DO CARBARIL EM COLUNAS DE SOLO SOB A INFLUÊNCIA DE DIFERENTES VOLUMES E pH DE PRECIPITAÇÃO

Abstract

In Brazil, the introduction of pesticides was carried out in an organized manner, accompanied by technological packages that introduced large-scale mechanization. In 2008, Brazil became the world's largest consumer of pesticides. According to research published by the National Health Surveillance Agency (ANVISA) and the Observatory of the Pesticides Industry of the Federal University of Paraná, presented in 2012, “while in the last ten years the global pesticide market grew 93%, the Brazilian market grew 190%”. Carbaryl, which has the nomenclature methyl 1-naphthyl carbamate, the chemical formula C₁₂H₁₁NO₂ is a contact insecticide with high toxicity and wide range of uses, suitable for all types of crops. Leaching involves the vertical movement of pesticides along the soil profile, which occurs in conjunction with the infiltration of rainwater or irrigation. Soil columns have been widely used in experimental studies to evaluate the leaching potential of pesticides. In summary, this study aims to simulate different precipitations and pH, using soil column and high performance Liquid Chromatography. To carry out this study, after filling the columns together with the soil, a standard dose of Carbaryl was applied in 4 soil columns. After the application, different volumes were simulated, 50 mm, 100 mm (pH=4 and pH=5) and 150 mm of precipitation. Subsequently, soil samples were collected at different depths along the soil column. Carbaryl concentration was determined by the extraction method (SLE-LTP) and chromatographic analysis. It was observed that in a column simulating 150 mm of precipitation, the civet moved to a deeper soil profile than in a column simulating 50 mm of precipitation. In this column, the concentration of carbaryl was found only in its surface profile. The pH was varied and it was confirmed that the column with the lowest pH (pH=4) was favorable to carbaryl leaching, since the concentration of the active ingredient was found in the deep layers of the soil profile. When the precipitation simulations were performed at pH=5, carbaryl was detected only in the surface layer of the soil profile. Therefore, it appears that both precipitation and changes in pH can affect the movement of carbaryl in soils.