Integrated Assessment of Enviromental Polution by Pesticides in the Upper Valley of the Río Neuquén: Patagonia, Argentina.

PABLO A. MACCHI; CECILIA DUFILHO; MÓNICA C. SAVINI; LILIANA B. MONZA; LORENA A. LATINI; MARÍA M. INDACO; RUTH M. LOEWY

Bogotá

Workshop; 4th Latin American Pesticide Residue Workshop; 2013

Sociedad Colombiana de Ciencias Químicas

Eighty per cent of Argentine pear and apple exportations are produced in Northern Patagonia, in the Upper Valley of the Río Negro and Neuquén. This activity involves the use of agrochemicals of varying toxicity in conjunction with sexual confusion techniques. Under the frawork of a national proyect by the Universidad Nacioanl del Comahue and international cooperation projects with the International Atomic Energy Agency (CRP 20.D35, RLA 5053 and RLA5061), an integral and multidisciplinary approach was taken to assess the impact of these pesticides on sediments, superficial water and shallow groundwater. As the analytical results showed greater residue concentrations in groundwater than in drainage water (drainage CMax: 1.020 ppb; phreatic water level meter CMax: 23.2 ppb), we had to apply models that consider preferential flow pathways in the transport of pesticedes in the ground. Thus, the duel-porosity model MACRO was applied. This model was suitably calibrated and validated, allowing us to demostrate that azinphos-methyl reaches groundwater both through micropores and preferential flow pathways. Parallel to chemical monitoring, biomonitoring was performed with an aim to assess the impact of pesticides on benthic macroinvertebrate communities in the agricultural sub-basin drainage system. We calculated the toxic units (TU) resulting from the mixture of several pesticides in superficial water. The results, applying generalized linear models (GLM), suggested that taxonomic richness is inherent to each site and did not vary during the sampling periods. In contrast, the abundance of macroinvertebrates drecreased in those sites that presented high TU values during the pesticide application period. This integral approach allowed us to demostrate the mechanisms of pesticide transport once it comes into contact with the environment, as well as to obtain evidence on the negative effect of its presence on aquatic life.