Effects Of Arsenic Reducing Bacteria On Reduction And Release Of Arsenic And Iron In Paddy Soil

In order to acquire engonus arsenic reduction microbes from arsenic polluted soil,we collected arsenic polluted paddy soil from shimen realgar mining area and separated five strains of aerobic arsenic reducing bacteria SM4,SM9,SM12,SM14,SM15,arsenic and anaerobic sulfate-reducing bacteria group M,these strains can grow in high arsenic environment,During the experiment,we used the three different existence forms of arsenic(dissolved the As(Ⅴ),the adsorption state As(Ⅴ)and As(Ⅴ)in soil)as the sources of arsenic,and studied system migration and release characteristics of arsenic and iron in the under the influence of arsenic reducing bacteria,(1)The results show that the five strains of aerobic arsenic arsenic reducing bacteria.all have good survivability,and have strong ability of arsenic reduction.In the solution of 200 mg/L As(V),the five strains are able to reduce As(Ⅴ)completely to As(Ⅲ)within 24 h,in 2 mg/L As(Ⅴ)in the solution,reduce As(Ⅴ)completely to As(Ⅲ)within 12 h.And strain increased almost similarly in the two solution.(2)Anaerobic arsenic arsenic reducing bacteria group,although also has good tolerance and strong ability of arsenic reduction,but it need 3 days to transfer As(Ⅴ)completely to As(Ⅲ)in the solution of 200 mg/L As(Ⅴ),sodium acetate as carbon source is growth conditions.(3)Studies inferred that all arsenic reducing strains can used As(V)as electron acceptor,five strains of aerobic arsenic reducing bacteria can reduce the dissolved As(Ⅴ),the adsorption state As(Ⅴ)and Fe(Ⅲ),As(Ⅴ)and Fe(Ⅲ)in soil.Anaerobic reduction bacteria can also restore dissolved As(Ⅴ),the adsorption state As(Ⅴ)and Fe(Ⅲ),As(Ⅴ)in soil and Fe(Ⅲ).(4)Aerobic arsenic reduction strains SM14 can restore solid phase As(V)and Fe(Ⅲ),and the As(Ⅲ)and Fe(Ⅱ)released from solid phase to liquid phase.The biggest As(V)reduction amount to 3 mM during the reducing process of ferrihydrite on the adsorption of arsenic,the maximum Fe(Ⅲ)reduction amount to 4 m M.Studies show that As(Ⅴ)reductive microorganism plays an important role in the reduction and transformation of soil As and dissolution and release process.It has important application value for soil As pollution restoration.On the one hand,it can strengthen the extraction efficiency of super accumulation plant(such as centipede)by inoculating native aerobic As(Ⅴ)reducing bacteria,on the other hand,the anaerobic As(Ⅴ)can be used under the condition of flooding.The reducing bacteria promoted the dissolution and release of As from the unsteady soil to the overlying water,and then removed the activated As from the soil by drainage,and reduced the As bioavailability of soil.