TRANSFORMATION OF CHLORAMPHENICOL AND OXYTETRACYCLINE IN AQUACULTURE POND SEDIMENTS

Transformation processes of two antibiotics, chloramphenicol (CM) and oxytetracycline (OTC), in aquaculture pond sediments collected from a freshwater eel pond and a marine shrimp pond were investigated. The so rption rates of CM in the freshwater and marine sediment slurries (10% , wt/vol) were 4% and 2%, respectively. In contrast, the sorption rate s of OTC in the freshwater and marine sediment slurries (10%, wt/vol) were 99.8% and 90.3%, respectively. CM amended at 60-70 mg/L was trans formed within 4 days in the freshwater and marine pond sediment slurri es when incubated under anaerobic conditions, and within 12 days under aerobic conditions. OTC amended at 60-70 mg/L was not transformed aft er incubation for 70 days in the freshwater and marine pond sediment s lurries under anaerobic conditions. However, OTC wits transformed to u ndetectable levels within 47 days when incubation proceeded under aero bic conditions. OTC was in fact also removed in the sterile sediment s lurries under aerobic conditions during the incubation periods, althou gh its rates of removal were much lower than the rates in the active s ediment slurries. The transformation rates of CM were greater under an aerobic conditions than under aerobic conditions at all concentrations (60-400 mg/L).