E-catalog        

Библиогр.: с. 139-141

Olivine is an important mineral that controls the sequestration of atmospheric CO2 in the form of secondary carbonate
minerals during chemical and biological weathering of mafic rocks on Earth. Despite significant efforts in characterization
of olivine reactivity and coupled secondary mineral precipitation both in abiotic and biotic systems, little is known on olivine
behavior in the presence of bacterial consortia, which are the dominant forms of microbial life impacting mineral reactivity in
natural settings. To address this gap, we studied the interaction of olivine with a bacterial consortium composed of typical
freshwater cyanobacterium Synechococcus sp. and heterotrophic aerobic Pseudomonas reactans, isolated from a CO2 storage
site in Icelandic basalts. We quantified the impact of this consortium on the dissolution rate of olivine and we characterized
the precipitation of secondary mineral phases while monitoring various biological (number of cells, bacterial biomass) and
physicochemical (pH, Si, Mg, Ca, alkalinity, dissolved organic and inorganic carbon) parameters of the medium over a period
of 21 days. Heterotrophic bacteria and their organic exometabolites enhanced the release of Mg and Si and produced leaching
features (etch pits) at the olivine surface whereas cyanobacterial photosynthesis raised the pH and favored precipitation of
hydrous Mg carbonates and silicates in the vicinity of the cells. During microbially-induced transformation of aquatic carbon,
the latter was sequestered in the form of cyanobacterial biomass (about 66%) and their soluble organic exometabolites (11%),
and stored as secondary Mg carbonates (23%). Overall, the impact of bacterial consortium is higher than that of individual
species and may represent important and understudied biotically-controlled mechanism of CO2 sequestration in natural
waters.