Carbon Isotope Fractionation of Organic Contaminants Due to Retardation on Humic Substances:  Implications for Natural Attenuation Studies in Aquifers

2005 ◽  
Vol 39 (16) ◽  
pp. 6052-6062 ◽  
Author(s):  
Frank-Dieter Kopinke ◽  
Anett Georgi ◽  
Michael Voskamp ◽  
Hans H. Richnow
Keyword(s):  
Humic Substances ◽  
Carbon Isotope ◽  
Natural Attenuation ◽  
Organic Contaminants ◽  
Isotope Fractionation ◽  
Carbon Isotope Fractionation

scholarly journals Modelling the Spatial and Temporal Trends of Carbon Isotope Fractionation of VOC Mixtures in the Unsaturated Zone

2013 ◽  
Vol 7 (2) ◽  
pp. 155-162
Keyword(s):  
Numerical Modeling ◽  
Carbon Isotope ◽  
Organic Compounds ◽  
Organic Contaminants ◽  
Unsaturated Zone ◽  
Isotope Ratio ◽  
Isotope Fractionation ◽  
Carbon Isotope Fractionation ◽  
Volatile Organic ◽  
Voc Mixtures

The transport of volatile organic contaminant (VOC) mixtures in the unsaturated zone is typically controlled by a combination of transport (i.e., advection, dispersion, and diffusion) phenomena, phase change (i.e., volatilization, dissolution) and reaction processes (i.e., sorption, biodegradation). As revealed from field and laboratory studies, biodegradation is probably the most important attenuation mechanism of VOCs in the unsaturated zone since it transforms organic contaminants to harmless products. However, in field applications, it is usually difficult, time consuming, or expensive to distinguish and quantify biodegradation among the different natural phenomena and processes, such as diffusion, dispersion, volatilization and sorption, without the aid of numerical modeling. Recent experimental studies showed large variations in space and time in the 13C/12C ratio for many organic compounds and suggested the possibility of using carbon isotope fractionation as a tool to assess biodegradation of organic contaminants in the unsaturated zone. The processes that were indicated to likely have the largest effect on the observed isotope ratio variations are (i) diffusion, which results in molecules with lighter isotopes to diffuse slightly faster than molecules with heavier isotopes, and (ii) biodegradation as a consequence of a preferential breakdown of the chemical bonds of the lighter isotopes. This study used numerical modeling of VOC mixture transport in the unsaturated zone to quantify the contribution of diffusion and biodegradation to carbon isotope fractionation of individual compounds, and to evaluate the use of 13C/12C ratio as a possible tool to assess biodegradation of organic contaminants. The numerical model incorporated transport of carbon isotope fractions of selected organic compounds and used data from a controlled fuel source emplacement field experiment and parameters from laboratory-scale studies. Costeffective modelling of the transport and fate of volatile organic contaminant mixtures was realized with the use of the recently developed constituent averaging technique [1]. Results indicated that (i) both diffusion and biodegradation lead to enrichment in 13C compared to the initial isotope ratio in locations within and close to the contaminant source, (ii) biodegradation lead to enrichment in 13C while diffusion resulted in smaller 13C/12C ratio in locations further away from the source, and (iii) the above effect of both processes on the isotope ratio was increased as a function of time. Modelling results showed that the use of carbon isotope fractionation at the field represents a promising tool for assessing and possibly quantifying biodegradation of organic contaminants in the unsaturated zone.

scholarly journals Carbon Isotope Fractionation during the Formation of CO2 Hydrate and Equilibrium Pressures of 12CO2 and 13CO2 Hydrates

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4215
Author(s):  
Hiromi Kimura ◽  
Go Fuseya ◽  
Satoshi Takeya ◽  
Akihiro Hachikubo
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Small Difference ◽  
Hydrate Formation ◽  
Formation Temperature ◽  
Carbon Isotope Fractionation ◽  
Unit Cell Size ◽  
Naturally Occurring ◽  
Three Phase ◽  
The Difference

Knowledge of carbon isotope fractionation is needed in order to discuss the formation and dissociation of naturally occurring CO2 hydrates. We investigated carbon isotope fractionation during CO2 hydrate formation and measured the three-phase equilibria of 12CO2–H2O and 13CO2–H2O systems. From a crystal structure viewpoint, the difference in the Raman spectra of hydrate-bound 12CO2 and 13CO2 was revealed, although their unit cell size was similar. The δ13C of hydrate-bound CO2 was lower than that of the residual CO2 (1.0–1.5‰) in a formation temperature ranging between 226 K and 278 K. The results show that the small difference between equilibrium pressures of ~0.01 MPa in 12CO2 and 13CO2 hydrates causes carbon isotope fractionation of ~1‰. However, the difference between equilibrium pressures in the 12CO2–H2O and 13CO2–H2O systems was smaller than the standard uncertainties of measurement; more accurate pressure measurement is required for quantitative discussion.

Large-scale carbon isotope fractionation in evaporites and the generation of extremely 13C-enriched methane

Geology ◽  
2004 ◽  
Vol 32 (6) ◽  
pp. 533 ◽  
Author(s):  
Joanna Potter ◽  
Michael G. Siemann ◽  
Mikhail Tsypukov
Keyword(s):  
Carbon Isotope ◽  
Large Scale ◽  
Isotope Fractionation ◽  
Carbon Isotope Fractionation

Carbon Isotope Fractionation in Noelaerhabdaceae Algae in Culture and a Critical Evaluation of the Alkenone Paleobarometer

2021 ◽  
Author(s):  
Samuel R. Phelps ◽  
Gwenn M. M. Hennon ◽  
Sonya T. Dyhrman ◽  
María D. Hernández‐Limón ◽  
Olivia M. Williamson ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Critical Evaluation ◽  
Carbon Isotope Fractionation

Microbial Dehalogenation of Trichlorinated Dibenzo-p-dioxins by aDehalococcoides-Containing Mixed Culture Is Coupled to Carbon Isotope Fractionation

2007 ◽  
Vol 41 (22) ◽  
pp. 7744-7751 ◽  
Author(s):  
Eva-Maria Ewald ◽  
Anke Wagner ◽  
Ivonne Nijenhuis ◽  
Hans-Hermann Richnow ◽  
Ute Lechner
Keyword(s):  
Mixed Culture ◽  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Carbon Isotope Fractionation

scholarly journals Carbon Isotope Fractionation by Ribulose-1,5-Bisophosphate Carboxylase from Various Organisms

1978 ◽  
Vol 61 (4) ◽  
pp. 680-687 ◽  
Author(s):  
Marilyn F. Estep ◽  
F. Robert Tabita ◽  
Patrick L. Parker ◽  
Chase Van Baalen
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Carbon Isotope Fractionation
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