study of the microbial degradation of toxaphene in fresh water sediment

background: toxaphene is a chlorinated hydrocarbon insecticide. the residues of which have been documented throughout the biosphere including water, ground water, soil and lake sediments, even though its use was banned some years ago. toxaphene has been known as an important environmental pollutant as a result of its persistence in the environment, bioaccumulation and bio magnification in food web. this study was conducted to characterize the degradation of toxaphene and the effect of energy sources for microorganisms under the flooded condition in irrigation ditch sediment . methods: the experiment was carried out in test tubes for 60 days in four parts with differences in the amount of toxaphene and being sterilized or not.. each part included three samples: unamend sediment, sediment amended with alfalfa meal and sediment amended with nutrient broth. throughout the incubation, single tubes from each sample were removed for analysis at selected times. after the extraction of toxaphene residue its gas chromatogram was qualified. in each sterilized part one set of autoclaved tubes was reinsulated after 60 days with sediment-water suspension . results: when sediment was autoclaved, no toxaphene degradation occurred, regardless of the presence of an energy source and the amount of toxaphene. when these samples were not autoclaved the degradation occurred in all samples. the overall order of toxaphene degradation was: sediment amended with alfalfa meal> sediment amended with nutrient broth > not amended sediment. when autoclaved sediment samples were reinsulated, toxaphene began to degrade . conclusion: the results indicate that biological processes caused toxaphene degradation in sediment and the addition of an energy source undoubtedly enhanced the degradative activity of micro flora in the sediment .