تجزيه بي هوازي حشره كش توكسافن در خاك تحت شرايط غرقاب

ANAEROBIC DEGRADATION OF TOXAPHENE INSECTICIDE IN SOIL UNDER FLOOD CONDITIONS

Introduction: The polychlorinated pesticide, toxaphene, is one of the most important persistent organic pollutants. Such persistence is due to lower degradation of toxaphene in soil and water. Results of an experiment on dry and moist soil samples amended with gin trash or not amended with it showed that notoxaphene degradation or dissipation had occurred. Because of these results, this experiment was conducted under "Flood" conditions to characterize the effectiveness of flooding on degradation of toxaphene in soil. Methods: The experiment was carried out on nine soil samples with different amounts of toxaphene and energy sources including gin trash and alfalfa meals for microorganisms. The experiment was conducted for three months. Toxaphene residues of samples taken at zero day and 3 months following initiation of the experiment were extracted and analyzed using a gas- liquid chromatograph. Results: Chromatograms of toxaphene residues indicate that extensive toxaphene decomposition occurred in samples amended with fresh gin trash or alfalfa meal. However, little or no toxaphene degradation occurred in samples not amended or those containing previously decomposed gin trash. Conclusion: The results of this study indicate that toxaphene decomposition in soils is a microbial process that 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 practical means for achieving degradation of toxaphene in the field, thereby reducing the environmental levels of this insecticide.