Thus, a rapid and extensive reduction of sediments can promote the in situ immobilization of certain contaminants. Dr. Lovley's laboratory is currently addressing these issues. Because of their ability to access small pore spaces and solid surfaces, HAs act as electron shuttles between the bacteria and the oxides. We know that the quinones, functional groups associated with HAs, are utilized as electron acceptors during respiration by the bacteria. These quinones are reduced to hydroquinones, which are free to move to the oxide surface.
Contaminants can also reside in inaccessible pore spaces.
This moves into the other area of your project, the use of DIRBs in the reduction of uranium in the presence of iron and manganese. Iron and manganese oxides are common mineral forms in oxidized sediments and are present in the subsurface at many sites contaminated with uranium. Derek Lovley and colleagues found that, in the presence of certain bacteria that reduce iron, uranium is enzymatically reduced. These organisms include Shewanella putrefaciens, Desulfovibrio desulfuricans , and G. metallireducens . It is currently unclear what effect these oxides may have on the reduction of radionuclides such as U for in situ bioremediation applications.