Estudo da lixiviação do carbaril sob a influência de chuva ácida.

Abstract

The use of pesticides is a very controversial and very worrying topic because on the one hand there are agribusiness practices, a fundamental economic sector considered one of the driving forces of the Brazilian economy. On the other side is the problem of the unbridled use of these products for profit and that cause serious risks to the environment and human beings. In addition to excessive use, there are other problems such as the weakness of Brazilian legislation that favors the approval of hundreds of pesticide records for manufacturing and use in the country, these and other problems significantly contributed to our country leading the world ranking of pesticide use. Carbaryl is an insecticide that is among the most used in the country due to its indication for different types of crops and its toxicity level for the environment is high. In addition to the risks caused by the application of this product, another problem can further aggravate the contamination of soil and water, the acid rain that is increasingly frequent, especially in large urban centers, due to the great demand from industries, but it can also extend around these areas by the action of the winds. Considering the great use of this insecticide in crops and the lack of knowledge about the effects of this active principle in the environment under acid rain, the objective of this research was to analyze in the laboratory the leaching potential of carbaryl in soil columns in two bands of pH=4 and pH=5. To carry out the analysis, soil columns, of the red oxisol type, were filled and doses of the active principle carbaryl were applied, based on the recommendations of the commercial product SEVIN®. Subsequently, precipitations with pH=4 and pH=5 values were simulated at the top of each column. After the precipitation simulation, soil samples were collected along the column profile (0-20 cm; 25-35 cm and 35-45 cm) in depth. Solid-liquid extraction with low temperature partitioning (SLE-LTP) and analysis by high performance liquid chromatography (HPLC) were used to determine the concentration of carbaryl present in the soil. The analyzes were carried out and the methods used proved to be efficient with satisfactory results. Carbaryl under acidic rain conditions (pH 4.0) showed higher leaching potential (25-35 cm) compared to normal rain pH (5.0), which remained at lower depths (0-20 cm), indicating that the degree of acidity can favor the leaching of carbaryl.