Microbially Induced Magnesium Carbonate Precipitation and its Potential Application in Combating Desertification

Abstract

This study investigated the reaction processes of microbially induced magnesium carbonate precipitation (MIMP) with Sporosarcina pasteurii (ATCC 11859) and evaluated its feasibility for controlling desertification in the desert areas in Northwest China. We explored systematically bacterial growth curves, mineralogy of precipitates, and relative chemical conversion efficiencies of the reaction using magnesium carbonate and bacterial urea hydrolysis with Sporosarcina pasteurii. We also compared the results of MIMP with the previously, well-studied microbially induced calcium carbonate precipitation (MICP). Our results indicate that excess Mg2+ motivated bacterial growth slightly. Magnesium carbonate precipitates appeared as nesquehonite, Mg-amorphous calcium carbonate, and Mg-rich calcite. The relative chemical conversion efficiency was higher in Mg medium than in Ca medium. We next evaluated the potential of using MIMP to mitigate desertification. We validated our results using the Mg-rich solution obtained by dissolving abandoned Mg salts that formed from the potassium salt plants nearby salt lakes. MIMP could potentially overcome shortcomings of traditional sand fixing methods, and was particularly suitable for controlling desertification in desert areas in Northwest China where there are abundant Mg resources. If MIMP works at field scales, this approach would further benefit ecosystem reconstruction because MIMP has main products of organic nutrients and ammonia, which would facilitate the development of biomass and soils. Overall, this work provides new insights into MIMP and its geoengineering potential in controlling desertification.