Acta Petrologica et Mineralogica

To analyze the effects of microorganisms and clay minerals on the amount, mineral type, and mechanism of carbonate mineral precipitation, Cladosporium and illite, which can induce dolomite precipitation, were used as exogenous factors to simulate the conditions suitable for the survival of Cladosporium. The induced precipitation of carbonate minerals in marine solutions was investigated through an experiment, using a nutrient broth culture medium with Mg²⁺/Ca²⁺=8, at 30℃. The culture period was set to 1, 3, 5, 10, and 15 days. Following the culture, the pH value was recorded, and Mg²⁺ and Ca²⁺ concentrations were sampled and measured, whereupon the precipitates were collected for analysis via scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction to examine the effects of different precipitation systems on the precipitation of carbonate minerals. The experimental results revealed many types of precipitates underlying the microbial precipitation system, including high-magnesium calcite and micron-sized protodolomite minerals. In clay mineral precipitation, the precipitates comprised mainly high-magnesium calcite, calcite, and nanoscale protodolomite. In the co-precipitation system, where the results of multiple tests were similar to those obtained in the clay mineral system, the precipitates were primarily calcite and dolomite nanospheres, suggesting that clay minerals do not promote the formation of carbonate minerals induced by microorganisms. Therefore, as a microorganism, Cladosporium has a greater impact on the quantity and rate of carbonate mineral precipitation than illite, and this may be because microorganisms can continuously provide carbonate ions into the precipitation system solution, thus accelerating the precipitation of carbonate minerals.

carbonate minerals; microorganisms; clay mineral; precipitation