Effect of Indigenous Bacteria Activity on the Release of Arsenic from Sediment in Different Anaerobic Environment

To investigate the effect of indigenous bacteria activity on the release of arsenic from sediment in CH4 and N2 atmosphere,microcosm experiments were conducted with an indigenous bacteria strain named YH001,which was isolated from high arsenic aquifer sediment of the Hetao Plain.Experiment results showed that the pH of suspension reduced to 7.0,Fe concentration of supernatant increased rapidly and reached the maximum value of 8.17 mg/L and As concentration increased to 64 μg/L on the 14thday under N2 atmosphere.However,in CH4 atmosphere,the pH of supernatant reduced to 7.5 and As concentration increased to 84.8 μg/L,while Fe concentration decreased gradually in the first 14 days.Both experiments indicated that microbial activities can significant mobilize arsenic under different anaerobic conditions,while the process controlling the arsenic mobilization may be different.Indigenous bacteria-mediated reduction of Fe oxides would greatly contribute to As mobilization in aquifer sediments,while there is no evidence of iron mobilization in CH4 atmosphere in the experiments.