Papers by Author: Zhi Feng Zhang

Abstract: Florfenicol is an effective antibacterial that is widely used in aquaculture farms. The current paper aims to investigate the potential influences of florfenicol on the growth and activities of microorganisms in the sediments of the Dalian coastal area using spiked experiments. The florfenicol resistance of heterotrophic bacteria in the sediment samples from different stations is also analyzed. The results show that florfenicol inhibits the growth and nitrification rates of both ammonia- and nitrite-oxidizing bacteria. Moreover, the sediment samples from stations which previously used florfenicol or other antibacterials had higher percentages of florfenicol-resistant bacteria, indicating that the resistance of heterotrophic bacteria in the sediments developed due to the use of antibacterials.

Abstract: The diffusion fluxes of dissolved inorganic nitrogen (DIN) and phosphate (DP) between sediment and water were estimated using Fick’s first law in the area near the sediment dredging location and in the dredged area of Dalian Bay during different seasons. The environmental properties of the studied areas were also investigated. The temperature, pH, dissolved oxygen, and salinity of the bottom water of the two studied areas did not exhibit remarkable differences. The DIN and DP diffusive flux near the sediment dredging area were larger, and the content of organic matters in the sediment was higher compared with the dredged area. In conclusion, sediment dredging induced the accumulation of organic matters in the surface sediment of nearby areas and accelerated the release of DIN and DP from the sediment. Sediment dredging is thus concluded to be among the primary factors contributing to the water eutrophication in Dalian Bay.