Tubercie deposits collected from pipelines in the Columbus, Ohio, distribution system and examined for their microbiological, chemical, and mineralogical composition were found to contain several kinds of organisms, including sulfate reducers, nitrate reducers, nitrite oxidizers, ammonia oxidizers, sulfur oxidizers, and various unidentified heterotrophic microorganisms. Chemical analysis revealed that the tubercies consisted largely of iron oxides, although minor and trace elements were present in varying quantities.
The purpose of this study was to assess the weathering of finely ground phlogopite, a trioctahedral mica, by placing it in contact with heterotrophic (Bacillus cereus) and acidophilic (Acidithiobacillus ferrooxidans) cultures. X-ray diffraction analyses of the phlogopite sample before and after 24 weeks of contact in B. cereus cultures revealed a decrease in the characteristic peak intensities of phlogopite, indicating destruction of individual structural planes of the mica. No new solid phase products or interlayer structures were detected in B. cereus cultures. Acidithiobacillus ferrooxidans cultures enhanced the chemical dissolution of the mineral and formed partially weathered interlayer structures, where interlayer K was expelled and coupled with the precipitation of K-jarosite [KFe3(SO4)2(OH)6].
Rapakivi granite samples were incubated with Pseudomonas aeruginosa culture solutions in order to elucidate the possible role of bacteria in rapakivi (crumbling stone) disintegration. SEM micrographs showed micromorphological alterations on the incubated rapakivi surface at 21 to 23°C for 20 days. Elevated concentrations of Na, Ca, K, Fe, and Mg were detected in the culture solutions after incubation. Elemental oxide ratios [K 2 O : (Na 2 O + CaO)] in culture solutions were similar to those in rapakivi ovoids, suggesting a proportional dissolution pattern of these elements.
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