The Effect Of Florfenicol On Biogeochemical Cycling Of Biotic Material In Coastal Marine Sediment

A great part of unused antibacterials which were widely used in marine aquaculture farms all over the world will eventually enter the aquatic environment, it have the opportunities to affect the marine organism and depositional environment while killing pathogen, by which the biogeochemical cycling of material in marine sediment will be disturbed. The primary object of this research is to comprehensively evaluate environmental risk of florfenicol which is used frequently in aquaculture. The the environmental behavior of florfenicol and the environmental impacts of florfenicol in marine environment were studied. The main conclusions obtained are listed as follows:The analytical methods about residue determination of florfenicol in sea water and sediment by HPLC and LC-MS/MS were established. The detection limit of HPLC and LC-MS/MS method was 40 and 0.01μg/L, respectivly.The initial concentration, temperature, the activity of microorganism and the content of organic matter were all had influences on the degradation of florfenicol in the sediment. The adsorption coefficient was no obvious change after the removing organic matter from the sediment and it became lower with the increasing of ion strength, pH, and temperature.High concentration of florfenicol could apparently inhibit the density and activities of microorganism and the influence became slightly with the degradation of florfenicol. Florfenicol could inhibit the activities of extracellular enzyme, cellulosic decomposition, respiration, the growth of AOB, NOB and sulphur bacteria in sediment in different degree.The community diversity of microorganism in sediment was change under the pressure of florfenicol.Florfenicol at lower concentration could induce antioxidase activities of Chlorella vulgaris and Ruditapes philippinarum, but inhibition occurred at higher concentration. Florfenicol could inhibit the activities of Na~+K~+-ATP and GR obviously at different concentration. Florfenicol at higher concentration could aslo inhibit the growth, the formation of chlorophyl and protein of Chlorella vulgaris.5. Florfenicol will lead to accumulation of material in sediment and it became more obvious in deeper of the sediment. The influences of florfenicol on the diffusion fluxes of material at sediment-water interface were apparently. Furthermore, florfenicol could inhibit the variation of Eh and sulfides in the sediment.6. The investigation in aquaculture areas in Dalian coastal zone showed that six seawater samples have been detected florfenicol residues among eleven stations. The bacteria resistance to florfenicol in sediment had increased due to the use of antibiotics and the resistance of bacteria became stronger in the areas which have been detected florfenicol residues. Moreover, function diversity indexes of microorganism in sediment were lower than the areas where antibacterials were not uesd before.