Experimental study on the decontamination kinetics of seawater polluted by oxytetracycline contained in effluents released from a fish farm located in a salt-marsh

Abstract

A rapid procedure for the quantitative determination of oxytetracycline (OTC) in seawater using high performance liquid chromatography is presented. The limits of detection and determination were respectively 0.01 μg/ml and 0.05 μg/ml (precision ± 10%) when injecting a 50 μl sample of seawater. The mean recovery of OTC from the seawater was 91.9%. Also included is an experimental study of the OTC kinetics in seawater. Experimental shellfish farms were polluted by effuents containing OTC coming from an experimental fish farm located in a salt-marsh. The disappearance of OTC from seawater was faster in the fish farm than in the shellfish farms where two kinetic phases were observed; the first one with an average half-life of 30.27 h and the second one with a higher average half-life of 318.57 h. Only the first phase was studied because it was assumed that the second phase would be complicated by the disappearance of OTC occurring simultaneously with diffusion from the sediment and shellfish. The results varied between tanks because of the differences in temperature, light intensity and flow from one tank to another. Fourteen days after the end of the chemotherapy in the experimental fish farm, the average OTC concentration in seawater of the shellfish farms was 0.2 μg/ml.