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Referenztyp Zeitschriften
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Creative Commons Lizenz creative commons licence
Titel (primär) Mass-transfer-limited biodegradation at low concentrations—Evidence from reactive transport modeling of isotope profiles in a bench-scale aquifer
Autor Sun, F.; Mellage, A.; Gharasoo, M.; Melsbach, A.; Cao, X.; Zimmermann, R.; Griebler, C.; Thullner, M.; Cirpka, O.A.; Elsner, M.;
Journal / Serie Environmental Science & Technology
Erscheinungsjahr 2021
Department UMB;
Band/Volume 55
Heft 11
Sprache englisch;
Supplements https://pubs.acs.org/doi/suppl/10.1021/acs.est.0c08566/suppl_file/es0c08566_si_001.pdf
Keywords bioavailability; 2,6-dichlorobenzamide; reactive-transport model; flow-through system; GC-IRMS; CSIA
Abstract Organic contaminant degradation by suspended bacteria in chemostats has shown that isotope fractionation decreases dramatically when pollutant concentrations fall below the (half-saturation) Monod constant. This masked isotope fractionation implies that membrane transfer is slow relative to the enzyme turnover at μg L–1 substrate levels. Analogous evidence of mass transfer as a bottleneck for biodegradation in aquifer settings, where microbes are attached to the sediment, is lacking. A quasi-two-dimensional flow-through sediment microcosm/tank system enabled us to study the aerobic degradation of 2,6-dichlorobenzamide (BAM), while collecting sufficient samples at the outlet for compound-specific isotope analysis. By feeding an anoxic BAM solution through the center inlet port and dissolved oxygen (DO) above and below, strong transverse concentration cross-gradients of BAM and DO yielded zones of low (μg L–1) steady-state concentrations. We were able to simulate the profiles of concentrations and isotope ratios of the contaminant plume using a reactive transport model that accounted for a mass-transfer limitation into bacterial cells, where apparent isotope enrichment factors *ε decreased strongly below concentrations around 600 μg/L BAM. For the biodegradation of organic micropollutants, mass transfer into the cell emerges as a bottleneck, specifically at low (μg L–1) concentrations. Neglecting this effect when interpreting isotope ratios at field sites may lead to a significant underestimation of biodegradation.
ID 24754
dauerhafte UFZ-Verlinkung https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=24754
Sun, F., Mellage, A., Gharasoo, M., Melsbach, A., Cao, X., Zimmermann, R., Griebler, C., Thullner, M., Cirpka, O.A., Elsner, M. (2021):
Mass-transfer-limited biodegradation at low concentrations—Evidence from reactive transport modeling of isotope profiles in a bench-scale aquifer
Environ. Sci. Technol. 55 (11), 7386 - 7397