CONICET | Buscador de Institutos y Recursos Humanos

The use of pesticides in Argentina has been increased in the last fifteen years. Pesticides contribute to the obtainment of better crop yields, but little attention has been paid up to now to its transport and fate in the environment. Herbicides represent the main class of pesticides, which could contribute to water resources contamination, but also insecticides and fungicides show high potential to affect the water resources quality. Among these substances, triazines are the most frequently detected, atrazine and simazine showing the highest degree of frequency in the contamination of groundwater. Several studies (e.g. Azevedo et al, 2002) show that atrazine is one of the most frequently detected compounds in groundwater, generating serious environmental problems. The aim of this study is to analyse the risk of groundwater pollution with selected pesticides through simulations of their behaviour in soils of the region Rolling Pampas in Argentina. The results will be used to show the long-time impact of the actual pesticide application practises on the water resources, especially the groundwater. First a comparison between the pesticides used in Argentina and in the European Union was carried out. Some pesticides were selected among those that are still used in Argentina and which active substances are not longer allowed in the EU. Most of them are used in the study area. The active substances of the selected pesticides are for example: aldicarb, atrazine, azinphos-methyl, carbaryl, endosulfan, oxydemeton-methyl, simazine, triadimefon and trifluralin. Their physico-chemical characteristics were searched in the literature (e.g. PAN Database). Samples of soil profiles were collected in the region Rolling Pampa (Pampa ondulada) in Buenos Aires province of Argentina. The province has a humid climate and a mean temperature of 16 °C. The mean annual precipitation is 900 mm. Although precipitation is higher in the summer, the water budget balance (precipitation pot. evapotranspiration) is negative in this season. Soil samples were collected from undisturbed sites, located in different places in Escobar county (Garín, Maschwitz, Belen de Escobar, Loma Verde and Matheu), and analysed. The simulations of the transport of the substances were performed with the model PESTAN (EPA). The results of the simulations show that there is a high potential for the contamination of the groundwater resources by leaching of pesticides, especially atrazine.

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