Carbon isotope systematics of monoaromatic hydrocarbons: vaporization and adsorption experiments

Harrington, Rebecca R; Poulson, Simon R.; Drever, James I.; Colberg, Patricia J.S.; Kelly, Eugene F.

doi:10.1016/s0146-6380(99)00059-5

Cited by 179 publications

(155 citation statements)

References 39 publications

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“…Thus, the non-reactive positions ''dilute" the isotope effect. Since no bond cleavage occurs during phase transfer processes, isotopic fractionation is expected to be absent or very small during sorption, dissolution, and volatilisation of compounds, as shown by several studies (Dempster et al, 1997;Harrington et al, 1999;Huang et al, 1999;Poulson and Drever, 1999;Slater et al, 1999;Hunkeler and Aravena, 2000). A small sorption isotope effect was recently reported for benzene and toluene in an organic matter rich matrix (Kopinke et al, 2005).…”

Section: Introductionmentioning

confidence: 94%

Carbon isotope fractionation during aerobic biodegradation of n-alkanes and aromatic compounds in unsaturated sand

Bouchard

Hunkeler

Höhener

2008

Organic Geochemistry

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Microcosm experiments were conducted to quantify carbon isotope fractionation during aerobic biodegradation of n-alkanes (from C 3 to C 10 ) and monoaromatic hydrocarbons in unsaturated alluvial sand. In single compound experiments with n-alkanes, the largest enrichment factor was obtained for propane (À10.8 ± 0.7‰). The magnitude of the enrichment factor decreased with increasing number of carbon atoms from propane to n-decane (À0.2 ± 0.1‰). This trend can partly be explained by the decreasing probability that a 13 C is located at the reacting site in the molecule with increasing chain length. After correcting for the presence of non-reacting positions, a chain length dependence of the calculated apparent isotope effect persisted. This observation suggests that transport and binding steps before the actual reaction step become increasingly rate limiting with increasing chain length. For aromatic compounds tested individually, the enrichment factor was the largest (À1.4 ± 0.1‰) for benzene (B), followed by toluene (T) (À0.8 ± 0.1‰) and m-xylene (X) (À0.6 ± 0.1‰). Enrichment factors for BTX were systematically smaller than for n-alkanes with equivalent number of carbons, which is likely related to different biodegradation mechanisms. The study demonstrates that significant carbon isotope fractionation occurs during aerobic biodegradation of n-alkanes and aromatic compounds under unsaturated conditions and that the magnitude of isotope enrichment is linked to molecule size and molecule structure.

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Section: Introductionmentioning

confidence: 94%

Carbon isotope fractionation during aerobic biodegradation of n-alkanes and aromatic compounds in unsaturated sand

Bouchard

Hunkeler

Höhener

2008

Organic Geochemistry

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“…(5a) and (5b) defining the isotope fractionation factor. The following parameters were used: δ 13 C: -30‰ for C and H; h P/ l P: 1.0002 for C (Harrington et al, 1999), 1.005 for H (Kiss et al, 1972) …”

Section: Assessing Biodegradation Using Isotope Datamentioning

confidence: 99%

Analytical modelling of stable isotope fractionation of volatile organic compounds in the unsaturated zone

Bouchard¹,

Cornaton²,

Höhener³

et al. 2011

Journal of Contaminant Hydrology

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a b s t r a c tAnalytical models were developed that simulate stable isotope ratios of volatile organic compounds (VOCs) near a point source contamination in the unsaturated zone. The models describe diffusive transport of VOCs, biodegradation and source ageing. The mass transport is governed by Fick's law for diffusion. The equation for reactive transport of VOCs in the soil gas phase was solved for different source geometries and for different boundary conditions. Model results were compared to experimental data from a one-dimensional laboratory column and a radial-symmetric field experiment. The comparison yielded a satisfying agreement. The model results clearly illustrate the significant isotope fractionation by gas phase diffusion under transient state conditions. This leads to an initial depletion of heavy isotopes with increasing distance from the source. The isotope evolution of the source is governed by the combined effects of isotope fractionation due to vaporisation, diffusion and biodegradation. The net effect can lead to an enrichment or depletion of the heavy isotope in the remaining organic phase, depending on the compound and element considered. Finally, the isotope evolution of molecules migrating away from the source and undergoing degradation is governed by a combined degradation and diffusion isotope effect. This suggests that, in the unsaturated zone, the interpretation of biodegradation of VOC based on isotopic data must always be based on a model combining gas phase diffusion and degradation.

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“…Strict collection and preservation procedures are required to avoid the evaporation of a crude oil sample to facilitate the accurate determination of its LMWHs distribution, because even minor evaporation would affect the quality of the data (Cañipa-Morales et al 2003). Although compound-specific isotope analysis (CSIA) has become a powerful tool for oil characterization and correlation (Chung et al 1998;Odden et al 1998;Harris et al 1999;Whiticar and Snowdon 1999), few studies have considered the effect of evaporation on the d 13 C values of LMWHs (Harrington et al 1999;Shin and Lee 2010).…”

Section: Introductionmentioning

confidence: 99%

“…For example, the enrichment of 13 C in the vapor fraction was reported for the evaporation of benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) (D 13 C vapor-liquid & ?0.2%) (Harrington et al 1999), trichloroethylene (D 13 C vapor-liquid = ?0.1% to ?0.7%) , chlorinated aliphatic hydrocarbons (D 13 C vapor-liquid = ?0.31% for trichloroethene and D 13 C vapor-liquid = ?0.65% for dichloromethane) (Huang et al 1999), and MTBE (tert-butyl methyl ether, D 13 C vapor-liquid = ?0.2-0.5% in different physical contexts) (Kuder et al 2009). The enrichment of 13 C in the vapor phase could be explained by higher vapor pressure of 13 C-substituted organic compounds relative to 12 C-substituted organic compounds (Baertschi et al 1953;Narten and Kuhn 1961;Jancso and Van Hook 1974).…”

Section: Introductionmentioning

confidence: 99%

“…A few studies have explored the effects of mixture with water and adsorption to soil on carbon isotope fractionation (Harrington et al 1999;Slater et al 1999;Höhener et al 2003;Schüth et al 2003;Bouchard et al 2008a, b). No significant carbon isotope fractionation was observed during the equilibrium vaporization of aqueous solution of toluene and trichloroethylene (Slater et al 1999), the soil adsorption of BTEX (Harrington et al 1999) and the sorption of halogenated hydrocarbon compounds (trichloroethene, cis-dichloroethene, vinylchloride) and BTEX compounds onto activated carbon, lignite coke, and lignite (Schüth et al 2003). However, significant fractionation has been observed after passing some volatile organic compounds across alluvial sand (e.g., D 13 C vapor-liquid is -2.14 ± 0.22%, -1.73 ± 0.52%, and -1.55 ± 0.45% for n-pentane, n-hexane, and benzene, respectively) (Bouchard et al 2008b), and an unsaturated soil zone (Bouchard et al 2008a).…”

Section: Introductionmentioning

confidence: 99%

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Carbon isotopic fractionation during vaporization of low molecular weight hydrocarbons (C6–C12)

et al. 2017

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Three series of laboratory vaporization experiments were conducted to investigate the carbon isotope fractionation of low molecular weight hydrocarbons (LMWHs) during their progressive vaporization. In addition to the analysis of a synthetic oil mixture, individual compounds were also studied either as pure single phases or mixed with soil. This allowed influences of mixing effects and diffusion though soil on the fractionation to be elucidated. The LMWHs volatilized in two broad behavior patterns that depended on their molecular weight and boiling point. Vaporization significantly enriched the 13 C present in the remaining components of the C 6 -C 9 fraction, indicating that the vaporization is mainly kinetically controlled; the observed variations could be described with a Rayleigh fractionation model. In contrast, the heavier compounds (n-C 10 -n-C 12 ) showed less mass loss and almost no significant isotopic fractionation during vaporization, indicating that the isotope characteristics remained sufficiently constant for these hydrocarbons to be used to identify the source of an oil sample, e.g., the specific oil field or the origin of a spill. Furthermore, comparative studies suggested that matrix effects should be considered when the carbon isotope ratios of hydrocarbons are applied in the field.

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Carbon isotope systematics of monoaromatic hydrocarbons: vaporization and adsorption experiments

Cited by 179 publications

References 39 publications

Carbon isotope fractionation during aerobic biodegradation of n-alkanes and aromatic compounds in unsaturated sand

Carbon isotope fractionation during aerobic biodegradation of n-alkanes and aromatic compounds in unsaturated sand

Analytical modelling of stable isotope fractionation of volatile organic compounds in the unsaturated zone

Carbon isotopic fractionation during vaporization of low molecular weight hydrocarbons (C6–C12)

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