Patterns of groundwater concentration and fate of lindane in an irrigated semiarid area in Argentina

Abstract

Abstract-The pattern of lindane breakthrough to groundwater and its mobilization thereafter were observed in a semiarid irrigated agricultural basin in southern Argentina. The pesticide half-life in the unsaturated vadose zone and the realized K oc were estimated through parameter optimization techniques on the basis of an ad hoc developed fugacity model, and two existing models of the transport of pesticides in soils (RITZ, PRZM2). Although the estimated half-life values are in agreement with values reported in the literature for other areas, the K oc was lower than usually reported, indicating that the adsorption of the pesticide is controlled by the kinetics of soil water infiltration. The lindane concentration and groundwater conductivity fields over an area of about 2,700 km 2 were compared and similarities between the transport of the pesticide and soluble soil salts were inferred. These showed that lindane is transported dissolved in the upper aquifer and can accumulate at exfiltration areas at 10 to 30 km from the sites of its application. The relevance of considering the kinetic constraints imposed by the hydraulic conductivity of the soil profile and the partition with the soil organic matter are highlighted in relation to the prediction of pesticide environmental fate.

Nonpoint Sources

“…Metolachlor added to organo-clay complexes and then applied to soil leached less than the commercial formulation according to El-Nahhal et al (1999). Results of observing the pattern of lindane breakthrough to ground water and its mobilization thereafter in a semiarid irrigated agricultural basin in southern Argentina indicated that the half-life of lindane there was similar to those reported in other literature (Ares et al, 1999).…”