The Environmental Behavior Of Florphenicol On Coastal Environment

Antibacterial chemotherapy is applied in aquaculture throughout the world. Most antibacterials are used in intensive culture systems for the treatment and prevention of bacterial disease occurs most frequently and severely. These substances are supplied with the food pellets or used directly in water, and about 50%～90% antibiotics in uningested medicated feeds or faeces enter into environment, which will result in severe environmental problem and human health risk. In order to evaluate the environmental behavior of florphenicol, the degradation, the adsorption of florphenicol in marine environment were studied. The main conclusions obtained are listed as follows:The method about residue determination of florphenicol in sea water and sediment by HPLC was established. This method used 224nm as the wavelengh of ultraviolet detection, and used acetonitrile and water (23:77, V/V) as the mobile phase; under this condition, the detection limit was 0.04mg/L (kg). By the standard addition method, the recovery rate varied in the 99.1%～101.4% range, and the relative standard deviation was 2.39%～6.23% in sea water; the recovery rate varied in the 85.9%～97.9% range, and the relative standard deviation was 4.32%～6.50% in sediment.The study of florphenicol degradation in sediment demonstrated that all of the degradation process fitted well to the first-order kinetic equation. When the initial concentration of florphenicol was from 1 to 10 mg/kg, the increase of the concentration was benefit to the degradation of florfenicol in the sediment; but when the initial concentration increased to 25 mg/kg, the degradation half life prolonged. The increase of temperature was benefit to the degradation of florfenicol in the sediment from 10 to 30℃; while the degradation rate decreased when the temperature increased to 40℃. The degradation half-life of florphenicol in sterilized sediment and no organic matter sediment were far more than that in non-sterilized sediment and organic matter sediment respectively. Besides, the degradation rate under anaerobic condition was slightly more rapid than that under aerobic condition.The adsorption behavior of florphenicol in sediment under different condations was studied. The results showed that most of the adsorption prosess fitted well to Freundlich and Langmuir models. The adsorption coefficient was no obvious change between the sediment and the sediment removing organic matter(3.3473,3.0867). The decrease of the sediment concentration (increase of the water soil ratio) and the sediment diameter were both benefit to the adsorption of florphenicol in sediment. When the ion strength, pH, and temperature increased, the adsorption coefficient of florfenicol in sediment decreased.