| The results of laboratory and field experiments demonstrated that bacteria indigenous to a shallow oil-contaminated aquifer caused minerals to weather rapidly in microreaction zones created in the near vicinity of attached bacteria. Bacteria readily colonized clean mineral surfaces in both laboratory and field microcosms. Nannobodies (0.1;Feldspars, quartz, and, in some cases, calcite dissolved in the immediate vicinity of attached bacteria, even though the saturation indices for these minerals in the bulk ground water indicated that little to no dissolution should occur. Metabolic production of CO;Bacteria colonizing quartz and microcline were in close proximity to etch pits, exhibiting a spatial correlation between bacteria location and etch pits. The etch pits, however, were not localized at the actual contact surface of the microbe, and the euhedral shape and extent of etching suggest the mineral surface was in contact with an aqueous weathering fluid. Localized mineral etching is proposed to have occurred in a reaction zone at the bacteria/mineral interface where high concentrations of organic acids, formed by bacteria during metabolism of hydrocarbon, selectively mobilized silica from the mineral surface. |
