Date of Award
Master of Science (MS)
Stephan H. Nordeng
New approaches in carbonate geochemistry are aiding geoscientists in
understanding dolomite formation. Dolomite is largely absent in modern depositional
environments but is present in ancient rocks. The current problem is the inability to
synthesize it under low-temperature conditions in the laboratory. Until recently
laboratory preparation of dolomite required elevated temperatures (<100oC) to overcome
kinetic barriers. One novel approach involves using bacteria to overcome the kinetic
barriers that have frustrated efforts to synthesize dolomite at near surface temperatures.
This study presents preliminary results of experiments in which three strains of bacteria
were used to inoculate a magnesium deficient amorphous calcium carbonate (Mg-ACC)
2-: Mg2+: Ca2+ in 2:1:1 ratio). The bacteria used include an aerobic strain,
Virgibacillus marismortui (ATCCÎ 700626™) and two anaerobic strains, Desulfovibrio
desulfuricans subsp. deslufuricans (ATCCÎ²9577™) and Escherichia coli. All the
experiments were conducted at 30oC and 37˚C for 40 days. Preliminary XRD results are
consistent with the precipitation of a carbonate phase with a dolomite-like XRD peak
near 31˚ 2θ, Cu kα radiation. Similar peaks were not apparent for the experiments using
the aerobic strain nor the bacteria free control. These results indicate that the two strains
of anaerobic bacteria may aid in the formation of a magnesium-rich carbonate phase
similar to dolomite at low temperature, within short periods of time.
Jambulapati, Sreeram, "Precipitation Of Synthetic Dolomite At Low Tempearures With The Influence Of Microbes" (2017). Theses and Dissertations. 2238.