Microbial Control of Mineral–Groundwater Equilibria: Macroscale to Microscale
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- November 26, 2018
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processes that perturb general groundwater chemistry and therefore mineral–water equilibria; and microscale interactions, where attached organisms locally perturb mineral–water equilibria, potentially releasing limiting trace nutrients from the dissolving mineral.
In the contaminated unconfined glacio-fluvial aquifer near Bemidji, Minnesota, USA, carbonate chemistry is influenced primarily at the macroscale. Under oxic conditions, respiration by native aerobic heterotrophs produces excess carbon dioxide that promotes calcite and dolomite dissolution. Aerobic microorganisms do not colonize dolomite surfaces and few occur on calcite. Within the anoxic groundwater, calcite overgrowths form on uncolonized calcite cleavage surfaces, possibly due to the consumption of acidity by dissimilatory iron-reducing bacteria. As molecular oxygen concentration increases downgradient of the oil pool …