Weathering of Granite from the Damma Glacier Area: The Contribution of Cyanogenic Bacteria |
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| Authors: | Nuttakan Wongfun Michael Plötze Gerhard Furrer Helmut Brandl |
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| Affiliation: | 1. Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science , ETH Zurich , Zurich , Switzerland;2. Institute for Geotechnical Engineering, Department of Civil, Environmental and Geomatic Engineering , ETH Zurich , Zurich , Switzerland;3. Institute of Evolutionary Biology and Environmental Studies , University of Zurich , Zurich , Switzerland |
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| Abstract: | The dissolution potential of five cyanogenic bacteria was studied at 25°C during 32 days using granite material from the Damma glacier (Central Alps, Switzerland) as the sole source of nutrients. The bacterial species Pseudomonas fluorescens and Pseudomonas sp. CCOS 191 were the most effective to exudate various organic acids and consequently mobilized Fe. The molecular mechanisms include both, proton-promoted and ligand-promoted dissolution, preferentially at pH below 5 and in the pH range between 5.0 and 5.8, respectively. In addition, bacterially produced cyanide plays a minor role through the formation of soluble hexacyanoferrate complexes. To our knowledge, this study is the first that reveals the direct measurement of metal-cyanide complexes formed during biotic granite weathering. |
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| Keywords: | cyanogenic bacteria granite dissolution cyanide organic acids |
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