Effect of Microbial Weathering on Carbonate Rocks

The interaction between microorganisms and minerals can facilitate the process of exogenic biogeochemical reaction, which is one of the important research contents in exogenic geochemistry. Microbes and their geological effects were summarized, and a variety of microbial weathering phenomena toward carbonate rocks, especially on different microcosmic scales, were analyzed. Weathering products and mechanisms of carbonate rocks by microbes were also expounded. The authors put forward four microbial weathering mechanisms of carbonate rocks: (1) microorganisms grow on rock surface or in crevices, resulting in bio-corrosion, bio-erosion, and boring, and accelerate rock decomposition and weathering; (2) boring meshes produced by microbial colony could increase the efficient superficial area of chemical denudation of rocks and could lead to the intensification of rock surface weathering to promote mechanical erosion, and the microbial destruction and loosing of cementation structure of rock particles would also accelerate the decomposition of mineral particles; (3) rock weathering can be intensified by the effects of microbial water-keeping, acidification of organic acids secreted by microorganisms, and the release of CO2 induced by microbial respiration onto rock surface; (4) microorganisms obtain nutrition from rock surface to produce complicated organic ligands and promote the release of mineral elements in the growing process of microorganisms. Finally, how to carry out studies on the microbial weathering of carbonate rocks was proposed. The authors suggest to comprehensively exploit local low-grade mineral resources, which contain potassium and phosphate, and accelerate soil formation and evolution in karst regions by using microbial technology.