Biologically induced mineralization of dypingite by cyanobacteria from an alkaline wetland near Atlin, British Columbia, CanadaReportar como inadecuado




Biologically induced mineralization of dypingite by cyanobacteria from an alkaline wetland near Atlin, British Columbia, Canada - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Geochemical Transactions

, 8:13

First Online: 05 December 2007Received: 03 April 2007Accepted: 05 December 2007

Abstract

BackgroundThis study provides experimental evidence for biologically induced precipitation of magnesium carbonates, specifically dypingite Mg5CO34OH2·5H2O, by cyanobacteria from an alkaline wetland near Atlin, British Columbia. This wetland is part of a larger hydromagnesite Mg5CO34OH2·4H2O playa. Abiotic and biotic processes for magnesium carbonate precipitation in this environment are compared.

ResultsField observations show that evaporation of wetland water produces carbonate films of nesquehonite MgCO3·3H2O on the water surface and crusts on exposed surfaces. In contrast, benthic microbial mats possessing filamentous cyanobacteria Lyngbya sp. contain platy dypingite Mg5CO34OH2·5H2O and aragonite. Bulk carbonates in the benthic mats δC avg. = 6.7‰, δO avg. = 17.2‰ were isotopically distinguishable from abiotically formed nesquehonite δC avg. = 9.3‰, δO avg. = 24.9‰. Field and laboratory experiments, which emulated natural conditions, were conducted to provide insight into the processes for magnesium carbonate precipitation in this environment. Field microcosm experiments included an abiotic control and two microbial systems, one containing ambient wetland water and one amended with nutrients to simulate eutrophic conditions. The abiotic control developed an extensive crust of nesquehonite on its bottom surface during which Mg decreased by 16.7% relative to the starting concentration. In the microbial systems, precipitation occurred within the mats and was not simply due to the capturing of mineral grains settling out of the water column. Magnesium concentrations decreased by 22.2% and 38.7% in the microbial systems, respectively. Laboratory experiments using natural waters from the Atlin site produced rosettes and flakey globular aggregates of dypingite precipitated in association with filamentous cyanobacteria dominated biofilms cultured from the site, whereas the abiotic control again precipitated nesquehonite.

ConclusionMicrobial mats in the Atlin wetland create ideal conditions for biologically induced precipitation of dypingite and have presumably played a significant role in the development of this natural Mg-carbonate playa. This biogeochemical process represents an important link between the biosphere and the inorganic carbon pool.

Electronic supplementary materialThe online version of this article doi:10.1186-1467-4866-8-13 contains supplementary material, which is available to authorized users.

Download fulltext PDF



Autor: Ian M Power - Siobhan A Wilson - James M Thom - Gregory M Dipple - Gordon Southam

Fuente: https://link.springer.com/







Documentos relacionados