Study Effects Of Salinity And Pressure On The Reduction Rate Of Iron(â…¢) Oxyhydroxides By Two Dissimilatory Iron-reducing Bacterias

Since the 20th century, with the breakthrough of science and technology. The human beings expanded the range of the oceans form the surface to the deep sea biosphere. The dissimilatory iron-reducing baterias was an important part of the deep sea biosphere. The marine environment was so complex that we cloud not to use natural environment samples to carry out quantitative research. There were also many obstacles in the kinetics and mechanism. Therefore, we choose the pure dissimilatory iron-reducing bacterias to carry out the relevant quantitative research. It is so significance for the study of dissmilatory reduction.In this paper, we choesd salinity and pressure as the conditional parameters and two typical dissimilatory iron-reducing bacterias(Desulfuromonas palmitatis and Shewanella oneidensis)as the research objects to carry out the simulated study of the dissimilatory iron-reducing bacterias. There were two experiments parts of this paper:atmospheric pressure experiments and the high pressure experiments.Under atmospheric pressure, the experiments set up different salinities(NaCl concentration was 8g/L,15g/L,22g/L,38g/L) to explore the impact on the rate of the iron(Ⅲ) oxyhydroxides with the strain Desulfuromonas palmitatis. The measurments resulted by the number of bacterias, Fe2+ and total rion concentration in the reaction system, it showed that under differet salinities, bacterial growth curves were similar and the concentration of Fe2+ was rising up to 4.5mM and the total iron concentration decreased about 4.6mM in the 7 days.Under high pressure, the experiments set up differet pressures(0.1 MPa,10 MPa,30 MPa) to react with two differet iron(Ⅲ) oxyhydroxides:the ferrihydrite and goethite to compare S.oneidensis had effects on the rate of the iron(Ⅲ) oxyhydroxides reduction. The results of the experiments by measuring the pH, Fe2+ and total concentration to show that the optimum pressure of the S.oneidensis bacteria growthing was 30 MPa in the two different iron(Ⅲ) oxyhydroxides reduction system; The rate of the ferrihydrite was faster than goethite with the S.oneidensis bacteria in the same pressures.By analyzing the experimental results:(1)this paper demonstrated that there was no effects on the rate of iron(Ⅲ) oxyhydroxides reduction under different marine salinities and atmospheric pressure. The salinity would not have impact on the growth of the dissimilatory iron-reducing baterias.(2)Also,this paper demonstrated that the growthing of S.oneidensis bacteria was increading with the higher pressures under the range of 0-30MPa;(3)What’s more,this paper demonstrated that the regularment of the rate of the iron(Ⅲ) oxyhydroxides reduction under the high pressures was same as the atmospheric pressure;(4)Finally,this paper provided the reliable proof that the dissimilatory iron-reducing bacterias may paly a role in the biogeochemical cycling of the iron.