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Lookup NU author(s): Dr Charles Knapp,
Professor David Graham
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Mineral weathering plays an important role in the global cycling of carbon and metals and there is an increasing realization that subsurface microbial activity may be a key factor controlling specific biogeochemical reactions and their rates. Methanobactin (mb) is an extracellular copper-binding compound excreted by methanotrophs to acquire copper for the regulation of methane oxidation. Bioavailable Cu regulates the expression and activity of pMMO versus sMMO (particulate versus soluble methane monooxygenase, respectively), key enzymes responsible for bacterial methane oxidation. In this study, we investigate the effect of methanobactin on the dissolution of Cu-substituted borosilicate glass at low temperature and near neutral pH conditions, using batch dissolution experiments. Methanobactin promotes the dissolution of Cu-substituted glasses at rates faster than control experiments. Glasses with lower concentrations of copper (80 ppm) or no copper are dissolved more rapidly by methanobactin than those with more abundant copper (800 ppm). Within the first 2 hours of reaction, methanobactin sorption onto glass surfaces limits mass transfer of Cu into solution, and at higher concentrations (100 molal) of the ligand, inhibits dissolution rates of all glass formulations. These results suggest that both the concentration of methanobactin in solution and the solid phase Cu concentration impact silicate weathering rates and related cycling of carbon in near-surface geologic settings.
Author(s): Kulczycki E, Fowle DA, Knapp CW, Graham DW, Roberts JA
Publication type: Article
Publication status: Published
ISSN (print): 1472-4677
ISSN (electronic): 1472-4669
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