Azinphos Methyl Residues in Shallow Groundwater from the Fruit Production Region of Northern Patagonia, Argentina

Groundwater samples were collected from monitoring wells along an area of intensive fruit production. Different types of correlations were investigated between soil physicochemical characteristics, depths and agricultural practices with pesticide detection frequency. In the three analyzed periods azinphos methyl, S-(3,4-diydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl)-O,O-dimethyl phosphorodithioate, showed a definite seasonal behavior related to the application pattern, increasing its concentration in the aquifer from October to November-December and then decreasing towards March. Samples obtained during the non-spraying season showed that azinphos methyl residues were lower than detection limit (LOD).

An inverse correlation was observed between azinphos methyl concentration and the time elapsed since the last pesticide application. Seasonal events such as rain and irrigation influence the chemical concentration in the well, while no correlation was obtained between soil characteristics and azinphos methyl concentration. The soil attenuation capacity was not enough to prevent the presence of azinphos methyl in the aquifer during the application season.

Key Words:

• Azinphos methyl
• Groundwater
• Soil
• Leaching potential
• Pollution
• Insecticides
• Monitoring
• Contamination

ACKNOWLEDGMENTS

We are grateful to the Universidad Nacional del Comahue (Research contract I940), FONCYT (PICT98-03729 and PICTR02-00203) and Autoridad Interjurisdiccional de Cuencas de los Ríos Neuquen, Limay y Negro, Argentina, for financial support.