| The purpose of this project is to better understand the mechanisms of iron bioavailability and reduction in natural environments. This was done by examining the ability of cells to reduce iron when in direct contact with, or separate from the iron oxide in anaerobic soil microcosms. To separate iron from the cells, amorphous iron oxides were placed in semi-permeable dialysis membranes or entrapped within alginate beads. Both techniques demonstrated that direct cell-iron contact was unnecessary for iron reduction, but did result in a 10-fold increase in the iron reduction rate. A component in soil, possibly the humic acids, facilitates iron reduction when direct contact between cells and iron is not possible. Even with the addition of the synthetic iron chelator, nitrilotriacetic acid (NTA), the presence of soil was still necessary for iron reduction across the dialysis membrane and alginate beads.; The NTA-soil extract was characterized using and UV and IR spectroscopy and the results were compared against alkali-extracted humic acids from the same soil source, and commercial humic acids. (Abstract shortened by UMI.)... |
