Seasonal Charactristics Of Dissimilatory Iron Reduction And Orgianic Phosphorus Hydrolyisis

The dissimilatory reduction of iron oxide can affect the interfacial behavior and biogeochemical cycle of various elements;the adsorption and hydrolysis of organic phosphorus(OP)on the surface of iron oxide is the key mechanism affecting its transformation and interface regeneration.In this work,the dissimilatory iron-reducing bacteria were isolated and identified in sediments from Lake Wuliangsuhai.The adsorption and release process of OP,such as AEP,NaG6 P and ATP on/from goethite and hematite were discussed considering the seasonal characteristics of icebound season and non-icebound season;meanwhile the iron reduction and OP hydrolysis were also monitored during the adsorption and release process.It helps to understand the environmental effects of the iron reduction and OP hydrolysis,especially during icebound season.The main conclusions are as follows:1.The concentration of Fe(II)in the overlying water during the non-icebound season was significantly higher than that in the sterile control group(p<0.01),indicating that the iron dissimilatory reduction was driven by the isolated and purified microorganisms from Lake Wuliangsuhai.Due to the difference in specific surface area and solubility,the reduction rate of goethite was higher than hematite.2.In the non-icebound season,the hydrolysis of OP was jointly controlled by iron oxide-catalyzed nucleophilic substitution reaction and microbial enzymatic reaction,especially the latter.3.Compared with NaG6 P and ATP,the hydrolysis of AEP was more difficult to provide enough inorganic phosphorus source for the growth of iron reduction microorganisms,resulting in the slower process of iron oxide reduction.4.Comparatively,the activities of microorganism and enzyme were inhibited during the icebound season,however,the degree of dissimilatory iron reduction and OP hydrolysis in the icebound season was found significantly higher than the sterile control group(p<0.01),which provided the necessary nutrients for spring algae flourishing.The results listed the microbial processes during icebound season as the key factor of elements interface behavior,especially during the season reversal from Winter to Spring.5.Different pretreatments showed that the Fe(II)and DIP generated in the reaction can be adsorbed on the surface of iron oxide or coprecipitated,resulting in the underestimation of the degree of dissimilatory iron reduction and OP hydrolysis.