Microbial biomass: A catalyst for CaCO3 precipitation in advection-dominated transport regimes

Abstract

Microorganisms have long been thought to impact CaCO 3 precipitation, but determining the extent of their infl uence on sediment formation has been hampered by our inability to obtain direct experimental evidence about mineral formation processes in natural environments. We address this problem by conducting kinetic experiments within a modern terrestrial carbonate spring to determine aragonite precipitation rates and to quantify the relative infl uences of aragonite saturation state (Ω a ), microbial biomass concentration and microbial viability on CaCO 3 mineralization in advection-dominated transport regimes. At an Ω a value consistent with modern seawater (3.63 ± 0.09), our controlled in situ kinetic experiments show that: (1) the natural steady-state aragonite precipitation rate is more than twice that determined when microbial biomass on the aragonite mineral surface is depleted by 0.2 µm fi ltration; and (2) inhibiting microbial viability with ultraviolet (UV) irradiation has no signifi cant effect on the mean precipitation rate. Furthermore, our modeling of the CaCO 3 precipitation process, which uses the empirical crystal growth rate expression and additional in situ kinetic measurements, reveals that reducing biomass concentrations by 45% can decrease the empirical rate constant by more than an order of magnitude. These fi ndings strongly suggest that microorganisms catalyze CaCO 3 precipitation in advection-dominated systems and imply that changes in carbonate mineralization rates may have resulted from changes in local microbial biomass concentration throughout geologic history.

Silicate Dissolution in Las Pailas Thermal Field: Implications for Microbial Weathering in Acidic Volcanic Hydrothermal Spring Systems

“…Microorganisms have also been shown to influence the precipitation of secondary mineral phases, including calcite at Angel Terrace, Yellowstone National Park (Fouke et al 2000;Kandianis et al 2008), siliceous sinters at El Tatio geothermal field (Phoenix et al 2006) and Fe-oxides and jarosite from acid sulfate Orange springs in Waiotaupo geothermal area, New Zealand and an acid sulfate spring in Kyushu, Japan (Jones and Renaut 2007;Kawano and Tomita 2001). The formation of clays, particularly nontronite, has been observed in off-axis deep sea hydrothermal systems.…”

Thermogenic travertine deposits in Thermopylae hot springs (Greece) in association with cyanobacterial microflora

“…For that reason, in the latest studies a combination of geological and biological aspects are combined to investigate the biotic influence on CaCO 3 formation (Kandianis et al 2008;Dupraz et al 2009;Obst et al 2009;Fouke 2011;Okumura et al 2011Okumura et al , 2012Kamennaya et al 2012).…”

Variation in hydraulic conductivity with decreasing pH in a biologically-clogged porous medium

“…Microbes, for example, can lower the hydraulic conductivity of porous media by generating biomass that clogs pores and fractures (Baveye et al, 1998) including the pore space adjacent to CO 2 injection wells . Microbial biomass can also enhance calcite precipitation Kandianis et al, 2008;Mitchell et al, 2010). The effect that CO 2 injection has on the distribution of subsurface microbial biomass, therefore, can impact structural and mineral trapping, storage-formation capacity, and well injectivity.…”