Study On The Microbial Effects On The Interface Behavior Of Biogenic Elements

Dissimilatory iron reducing bacteria(DFeRB)and sulfate reducing bacteria(SRB)are important factors affecting the environmental geochemical behavior of biogenic elements such as carbon,nitrogen and phosphorus.It is of great significance to study the microbial effects on the interface behavior of biogenic elements.Based on the water-sediment interface behavior simulation experiment of carbon,nitrogen and phosphorus in Wuliangsuhai,this paper discussed the influence mechanism of two kinds of bacteria on the release of biogenic elements,compared the different effects of two kind bacteria on the release of biogenic elements in ice-sealed and non-ice-sealed periods,and explained the coupling relationship between carbon,nitrogen and phosphorus under the action of microorganisms.This paper draws the following main conclusions:1.Seasonal simulation results show that although the biological activity of microorganisms during ice-freezing period is low and the release rate of biogenic elements in sediments is significantly lower than that during non-ice-freezing period(p < 0.05),DFeRB and SRB still play a certain role in promoting the release of biogenic elements during ice-freezing period.The biogenic factors released by sediments during the ice-freezing period play an important role in initiating algae outbreaks in the coming year.2.In this experiment,the results of release flux of dissolved organic carbon as well as the concentration change of total nitrogen,ammonium nitrogen,total phosphorus and inorganic phosphorus during non-ice-freezing period are followed: adding bacteria group > no bacteria group.Under the same conditions,both DFeRB and SRB can promote the release of nitrogen and phosphorus,which indicates that the effect of microorganisms on the interface behavior of biogenic elements is an important link in the process of eutrophication.3.The results of correlation analysis showed that DOC concentration in overlying water was negatively correlated with ammonium nitrogen,total nitrogen and organic phosphorus concentration in plus DFeRB culture system(p < 0.05).It indicated that DFeRB could promote the decomposition of organic nitrogen in sediment and the release of phosphorus-containing substances on the surface of iron ore in the physiological process of using DOC as nutrient source,resulting in the sum of ammonium nitrogen,total nitrogen and organic phosphorus in overlying water.The concentration of DOC in overlying water was positively correlated with the concentration of total phosphorus,total nitrogen and ammonium nitrogen in plus SRB culture system.It may be that SRB enhanced the mineralization and degradation of organic matter in the process of reducing sulfate,as a result,increased the concentration of DOC,total nitrogen and total phosphorus in overlying water.4.In the early stage which microbial was in high activity,the concentrations of DOC,total nitrogen and total phosphorus in the adding SRB group were significantly higher than those in the adding DFeRB group(p < 0.05).The results show that,under the same conditions,SRB has a more significant effect on the interfacial behavior of biogenic elements.