Metabolism-Induced CaCO3 Biomineralization During Reactive Transport in a Micromodel: Implications for Porosity Alteration.
The ability of Pseudomonas stutzeri strain DCP-Ps1 to drive CaCO3 biomineralization has been investigated in a microfluidic flowcell (i.e., micromodel) that simulates subsurface porous media. Results indicate that CaCO3 precipitation occurs during NO3(-) reduction with a maximum saturation index (SIcalcite) of ∼1.56, but not when NO3(-) was removed, inactive biomass remained, and pH and alkalinity were adjusted to SIcalcite ∼ 1.56. CaCO3 precipitation was promoted by metabolically active cultures of strain DCP-Ps1, which at similar values of SIcalcite, have a more negative surface charge than inactive strain DCP-Ps1. A two-stage NO3(-) reduction (NO3(-) → NO2(-) → N2) pore-scale reactive transport model was used to evaluate denitrification kinetics, which was observed in the micromodel as upper (NO3(-) reduction) and lower (NO2(-) reduction) horizontal zones of biomass growth with CaCO3 precipitation exclusively in the lower zone. Model results are consistent with two biomass growth regions and indicate that precipitation occurred in the lower zone because the largest increase in pH and alkalinity is associated with NO2(-) reduction. CaCO3 precipitates typically occupied the entire vertical depth of pores and impacted porosity, permeability, and flow. This study provides a framework for incorporating microbial activity in biogeochemistry models, which often base biomineralization only on SI (caused by biotic or abiotic reactions) and, thereby, underpredict the extent of this complex process. These results have wide-ranging implications for understanding reactive transport in relevance to groundwater remediation, CO2 sequestration, and enhanced oil recovery.
Rajveer
R
Singh
Geoscience Research and Applications, Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
Hongkyu
H
Yoon
Robert A
RA
Sanford
Civil, Architectural and Environmental Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
Lynn
L
Katz
Bruce W
BW
Fouke
Civil, Architectural and Environmental Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
Charles J
CJ
Werth
D018533:Biomass; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism*; D011232:Chemical Precipitation; D058440:Denitrification; D060587:Groundwater; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008903:Minerals / Q000737:chemistry / Q000378:metabolism; D008962:Models, Theoretical; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D010539:Permeability; D016062:Porosity; D044223:Pseudomonas stutzeri / Q000378:metabolism*
D008903:Minerals; D009566:Nitrates; D002119:Calcium Carbonate