The role of Fe-oxidizing bacteria (FeOB) and organic matters in As removal in the heavy-polluted arid soil.

The bio-remediation of As-polluted farmlands in the arid area is seldomly reported. This study aimed at understanding the impact of DOM, Fe-oxides, and FeOB biogeochemical processes on As remediation. The approaches used included: FeOB strain Pseudomonas flavescens LZU-3; Batch-experiment. Our results showed that all FeOB tested effectively immobilized As (>95%) during microbial mineralization; DOM play an important role in the reduction of Fe(III)(hydr)oxides and As(V); Less-crystallized ferrihydrite transform to more-crystallized goethite and secondary minerals; Under the reaction of FeOB and DOM, the As-Fe-OM ternary compound were formed, containing N, S, C and O functional group; The addition of OM can clearly reduce soil Eh, promoting dissolution of As in bound to iron oxides, co-precipitation of the amorphous iron oxide in Fe(III)-OM-FeOB, closely related to As in bound to insoluble organics and sulfides and mineral residues, which plays an important role in controlling the mobilization of As. This study provides controlling of As transportation and transformation in the As-DOM-Bio-Fe ternary system as As-remediation technology in the arid soil.