Evaluation of pollution of groundwater resources by Carbofuran based on its adsorption on three soils by Spectrophotometry

Abstract

The adsorption studies of carbofuran on three natural soils of different characteristics were conducted under laboratory conditions at 20 and 30 ±1ºC with an objective to evaluate the risk of pollution of groundwater resources. An extractive spectrophotometric methodology based on the transformation of insecticide into methyl isobutyl ketone (MIBK), extractable yellow product absorbing at 380 nm has been developed for the purpose. Adsorption and mobility were found significantly correlated with each other and were greatly affected with organic matter and clay content of the soil. The adsorption study was carried out by batch equilibration procedure. Adsorption of carbofuran into the soil fits the Freundlich adsorption isotherm. This adsorption study has been observed to be a spontaneous and exothermic process. The measured adsorption coefficients were used to evaluate leaching potential in terms of Groundwater Ubiquity Score (GUS). The observed GUS values in the range between 2.71-3.22 indicated that the carbofuran acts as a leacher, thereby poses a potential risk to groundwater resources and therefore calls for its judicious use.