Research Of The Bacterium Effect In Fe,Mn,Ca Depositing

Exemplified by Dongge Cave, a karst cave in Southwest China, some special cave bacteria which could deposit Ca2+, Fe3+ and Mn2+ were screened and separated. Then the sedimentary processes of Ca2+, Fe3+ and Mn2+ by these bacteria were studied through simulated experiments, and the sedimentary mechanisms of bacteria were preliminarily discussed. Some results were obtained as follows. (1) 13 strains of resistant-acid bacteria, 7 strains of bacteria depositing Fe3+ and 3 strains of bacteria depositing Mn2+ were screened and obtained. (2) Resistant-acid bacteria had sedimentary effects on Ca2+, for example, strains Ca0441 and Ca0541 presented the sedimentary effects on Ca2+ with alkali production during incubation process. (3) Iron bacteria had sedimentary effects on Ca2+, Fe3+ and Mn2+, for example, strain Fe0502 deposited almost all of Ca2+ and Fe3+ in 4 h after growing to stable stage. (4) Manganese bacteria had obvious sedimentary effects on Ca2+ and Mn2+, but their sedimentary effects on Mn2+ were slower. (5) Analysis of X-Ray Fluorescence Spectrometer, X-Ray Diffractomer and electron energy dispersive spectrometer showed that the sediments which had bacterial action had the same elemental components and mineral ingredients as the original speleothem in cave, which suggested that bacteria was one of the important reasons of ferric and manganic deposits and nano-crystalloines forming, and also responsible for the change of deposit color and luster.These results would provide a scientific basis on further research of the bacterial effects in the cave deposit and microbial biomineralization as well as protection and restoration of scenery in travel caves.