Experimental study of the therapeutic application of oxytetracycline, its attenuation in sediment and sea water, and implications for farm culture of benthic organisms

Abstract

A rapid procedure is presented for the quantitative determination of oxytetracycline (OTC) in sediment using high-performance liquid chron~atography. The limits of detection and determination were respectively, 0.05 and 0.2 pg g-' wet weight of sediment when 50 kl of sample was injected. The mean recovery of OTC from the sediment was 57.5%. The method is used in an experimental study of the lunetics of OTC in the s e d m e n t of tanks. These tanks were polluted by a seawater effluent coming from another tank into which OTC was added (45 g d-' for 7 d). During medication, OTC concentrations in the sediment gradually increased to peak at a mean value of 4.05 kg g-l. The average half-life of OTC in the sediment was 60.4 d. Fourteen days after the end of medication, the OTC concentration in the sediment was still high (average 1.67 pg g-') The results varied between tanks because of slight differences in temperature, light intensity and water flow between them. The results indicate that OTC may be very persistent in the sediment and that the disappearance of OTC is faster in sea-water than in sediment. It is suggested that the formation of complexes between OTC and some components of the sediment, such a s divalent cations, might delay the release of OTC by sediment into sea-water It can b e assumed that benthic organisms living in this sediment may be also contaminated by OTC