Lixiviação de atrazina em solo em área de recarga do Aquífero Guarani

Abstract

The Espraiado watershed is located on a recharge area of the Guarany aquifer, the most important source of groundwater in South Central Brazil. The presence of crops in which herbicides of triazine group are used and sandy soils make the area vulnerable to leaching. One of the herbicide used is atrazine (2-chloro-4-(ethylamino)- 6-(isopropylamino)-S-triazine). Due to its physical and chemical characteristics, atrazine has a high potential to leach into groundwater. In order to evaluate atrazine leaching in the soil, surface and groundwater samples have been collected during the period of 2000 to 2002. Soil physical properties have been determined and water samples submitted to analysis by HPLC (High Performance Liquid Chromatography) followed by GC-MS (Gas chromatography-Mass Spectrometry) for confirmation. Among all surface water samples collected, only four have shown atrazine residues, two with 0.04 and others with 0.05 and 0.09 µg/L. Only one ground water sample has shown residue at level of 0.03 µg/L None of those sample residue level has been confirmed with the CG-MS thus indicating no residue. The leaching potential has also been evaluated by mathematical modelling simulation using the Chemical Movement in Layered Soils- CMLS-94. The simulator has also shown that atrazine did not reach the aquifer.