Manganese (Mn) oxides are highly reactive minerals ubiquitously found in soil and water systems. It is believed that most Mn oxides found in natural environments are of biological origin, and that fungal activity may be the main agent responsible for the formation of these minerals in contaminated environments. Furthermore, Mn oxides are known to play an important role in the cycling of metals, organic matter, and pollutants through sorption and redox reactions, and thus could be of use in engineered bioremediation systems. It is therefore crucial to further examine and understand the structure and redox properties of these minerals, and especially how such properties differ between abiotic and biogenic minerals. In the present study, two abiotic (δ-MnO2 and c-disordered birnessite) and three mycogenic Mn oxides (produced by three different strains of fungi isolated from a Superfund site in NC) were examined through (1) reductive dissolution experiments using substituted quinones (hydroquinone, chlorohydroquinone, and methylhydroquinone), and (2) cyclic voltammetry measurements. The dissolution experiments were conducted to measure the rate of manganese solubilization, whereas the cyclic voltammetry measurements were performed to determine the electron transfer rates for these species. Preliminary results suggest that abiotic and biogenic manganese oxides vary in their redox reactivity with the biogenic minerals displaying higher dissolution rates and faster electron transfer, making them potentially more effective in water treatment systems.

Quantifying mycogenic manganese oxide reactivity through chemical and electrochemical measurements

253rd National Meeting (2017)

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