TEM observation of bacteria-induced plagioclase dissolution and secondary mineral formation

Abstract:

Silicate minerals are the most common minerals in the earth’s crust. Bacteria are also distributed throughout the earth’s surface environment. The silicate minerals are known to be dissolved by organic acids and polysaccharides known as bacteria metabolites. The metabolic activity of bacteria therefore plays an important role in the interaction between dissolution of the silicate minerals and formation of secondary minerals. However, little is known about the secondary mineral formation process associated with the bacterial metabolism. To clarify the bacterial effect on the mineral dissolution and the secondary mineral formation, we closely investigated the effect of bacterial activity on surface texture modification and chemical composition changes of plagioclase which is the most abundant silicate mineral in the earth’s crust. The bacteria were isolated from soil and then added in a suitable medium with several plagioclase fragments (Ab100% and An100%). It was incubated for 10 days. Al and Si concentrations in the medium were measured by ICP-AES to monitor the dissolution of the plagioclase. Secondary mineral formation during the incubation was observed by TEM, EDS and SAED methods. The authors will give the experiment results and discuss the effect of bacterial activity on the plagioclase dissolution and the secondary mineral formation in detail.