Sponsor: National Nature Science Foundation of China (NNSFC)

Headed by Cui Haojie

Date: 2011.01-2013.12  

Birnessite is a common Mn oxide mineral in the Earth surface environments, and lithiophorite, todorokite and cryptomelane, which are commonly found in manganese nudles in soils, can be formed from birnessite through directly or indirectly reactions. The adsorption, oxidation and catalysis characteristics of manganese oxides depend on the results of their transformations. The environmental roles of substructure of birnessites have received wide spread attention, but few reports are about the effect of substructure of birnessites on their transformation. In this program, the birnessites with different substructure obtained by varied chemical synthesis and biogenic manganese oxides were used to investigate the effects and mechanisms of substructure of birnessites on their transformation to lithiophorite, todorokite and cryptomelane at near the Earth surface envrionments, which were established by analysing the manganese oxides minerals and elements compositions of natural typical manganese nodules and cutans and their natural environments. The results can exposure the roles of substructure of birnessites in determing the difference of type and amounts of manganese oxide minerals in natural environments. This study could have great significance in exploring the actives of manganese oxides in the envrionmental geochemistry and enriching the minerlas formation theories at the Earth’s surface.