An Index for Evaluating the Risk of Water Contamination by Pesticides: Development and Validation
EFL - University of Brasilia
Since the surface and groundwater are strategic and vulnerable environmental compartments, their contamination by pesticides could cause significant damage to man and the ecosystems. The objective of this study was to develop a simple and robust index (ARCA) to estimate the risk of water contamination by pesticides, in different agronomic and environmental settings, and to validate it at the field level. The risk of contamination (R) in the ARCA index is the product of the environmental vulnerability of the site (V) and the contamination potential of the pesticides (Pc). The vulnerability is the product of the clay content of the soil, the distance to the nearest stream, and the type of soil management. The contamination potential is given by the product of the pesticide mobility, persistence, and its toxicity to man and fish. An experiment was carried in a soybean field in Brasilia, Brazil, to validate the model. In that field study, the glyphosate concentration on the slope runoff and in the leachate were compared with the pesticide behavior predicted by the index. Furthermore, the glyphosate concentrations in the river downstream were compared with the risk calculated by the index. In both cases, the ARCA index correctly predicted the values and trends obtained in the field study. However, considering the limited scope of the field experiment, it is recommended that additional studies be carried, to better assess the validity of the ARCA index.