Electronic Thesis and Dissertation Repository


Master of Science




Dr. Gordon Southam


Two studies were conducted to investigate the biogeochemistry of platinum. In the first project, platinum nuggets were examined to evaluate mineral dissolution-precipitation processes occurring at the nugget-‘soil solution’ interface. The presence of dissolution ‘pits’, cavities, and striations as well as acicular, iron oxides coating the grain surface evidence that this interface is an important site of mechanical and chemical weathering. Element mapping revealed that structural and chemical signatures can be linked to morphological features on the grain surface. In the second study, the soil bacterium Cupriavidus metallidurans was reacted with aqueous platinum chloride and rapidly immobilised platinum. XANES/EXAFS analysis of these reaction systems demonstrated that platinum chloride bound to the bacteria and platinum binding shifted from chloride to carboxyl functional groups. TEM revealed that C. metallidurans was able to precipitate nm-scale colloidal platinum. Both of these studies highlight the importance of nanophase- and organo- platinum compounds in natural systems.