Anaerobic Microbial Degradation of Toxaphene in Soil

The polychlorinated pesticide toxaphene is one of the most important organic pollutants. The persistence of this pesticide is the result of low degradation of toxaphene in soil and water. Results of an experiment on dry and moist soil samples amended with gin trash or not amended showed that no toxaphen degradation or dissipation had occcured.there fore, this experiment was conducted under `Flooded` conditions to charactrize the effectiveness of flooding on degradation of toxaphene in soil. The exeperiement was carried out on nine soil samples with different amount of toxaphene and energy sources including gin trash and alfalfa meal for microorganisms. The experiment was conducted for three months. Toxaphene residues of samples taken an day zero and 3 months following the initiation of the experiment were extracted and analyzed using a gas- liquid chromatography. Chromatograms of toxaphene residues indicated the extensive toxaphene decomposition occurred in samples amended with fresh gin trash or alfalfa meal. However, little or no toxaphene degradation occurred in samples which were not amended or those containing previously decomposed gin trash. The results of this study indcated that toxaphene decomposition in soil is a microbial process which takes place under anaerobic conditions. Moreover, addition of an energy source enhances the degradative activity of the microflora. Therefore, incorporation of organic material with the soil and subsequent flooding might be a practical means of achieving degradation of toxaphene in the field thereby reducing the environmental levels of this insecticide.