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Title (Primary) Assessment of the impact of pore-scale mass-transfer restrictions on microbially-induced stable-isotope fractionation
Author Heße, F.; Prykhodko, V.; Attinger, S.; Thullner, M.;
Journal Advances in Water Resources
Year 2014
Department CHS; UMB;
Volume 74
Language englisch;
POF III (all) T53;
Keywords Compound-specific stable-isotope analysis; CSIA; Bioavailability; Numerical modeling; Linear-exchange model; Michaelis–Menten kinetics
UFZ wide themes RU5;
Abstract

Stable-isotope fractionation has become an established method for the assessment of contaminant biodegradation in groundwater. At the pore scale however, mass-transfer processes can limit the bioavailability of chemical species and therefore affect the observed fractionation. This can challenge the application of stable-isotope analysis in practice. A linear-exchange model provides a computational link between the microbially-induced isotope fractionation, determined under ideal conditions, and the fractionation observed under conditions of limited bioavailability. This simplifying conceptual approach allows for accurately estimating the mass-transfer limited degradation rates but its applicability for stable-isotope fractionation at the pore scale has not been evaluated yet. In this study, we perform high-resolution numerical simulations of microbial degradation and stable-isotope fractionation of a chemical species in a pore-scale model. The numerical results are compared to theoretical predictions derived from the linear-exchange model. Our results show an overall good agreement between numerical simulations and theoretical predictions, which confirms the applicability of the theoretical approach and of the value for the mass-transfer coefficient previously derived from the geometry of the pore space. In addition we provide a quantitative link between the value of the observable fractionation factor and the effective bioavailability of a biodegradable contaminant.

ID 15649
Persistent UFZ Identifier http://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=15649
Heße, F., Prykhodko, V., Attinger, S., Thullner, M. (2014):
Assessment of the impact of pore-scale mass-transfer restrictions on microbially-induced stable-isotope fractionation
Adv. Water Resour. 74 , 79 - 90