Université de Neuchâtel

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

Bouchard, Daniel ; Cornaton, Fabien ; Höhener, P ; Hunkeler, Daniel

In: Journal of Contaminant Hydrology, 2011, vol. 119, p. 44-54

Analytical 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...

Université de Neuchâtel

Carbon Isotope Fractionation During Volatilization of Petroleum Hydrocarbons and Diffusion Across a Porous Medium: A Column Experiment

Bouchard, Daniel ; Höhener, Patrick ; Hunkeler, Daniel

In: Environmental Science & Technology, 2008, vol. 42, no. 21, p. 7801–7806

The study focuses on the effect of volatilization, diffusion, and biodegradation on the isotope evolution of volatile organic compounds (VOCs) in a 1.06 m long column filled with alluvial sand. A liquid mixture of 10 VOCs was placed at one end of the column, and measurements of VOC vapor concentrations and compound-specific isotope ratios (δ13C) were performed at the source and along...

Université de Neuchâtel

Carbon Isotope Fractionation during Diffusion and Biodegradation of Petroleum Hydrocarbons in the Unsaturated Zone: Field Experiment at Værløse Airbase, Denmark, and Modeling

Bouchard, Daniel ; Hunkeler, Daniel ; Gaganis, Petros ; Aravena, Ramon ; Höhener, Patrick ; Broholm, Mette M.

In: Environmental Science & Technology, 2008, vol. 42, no. 2, p. 596–601

A field experiment was conducted in Denmark in order to evaluate the fate of 13 volatile organic compounds (VOCs) that were buried as an artificial fuel source in the unsaturated zone. Compound-specific isotope analysis showed distinct phases in the 13C/12C ratio evolution in VOC vapors within 3 m from the source over 114 days. At day 3 and to a lesser extent at day 6, the...

Université de Neuchâtel

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

Bouchard, Daniel ; Hunkeler, Daniel ; Höhener, Patrick

In: Organic Geochemistry, 2008, vol. 39, no. 1, p. 23-33

Microcosm experiments were conducted to quantify carbon isotope fractionation during aerobic biodegradation of n-alkanes (from C3 to C10) and monoaromatic hydrocarbons in unsaturated alluvial sand. In single compound experiments with n-alkanes, the largest enrichment factor was obtained for propane (−10.8 ± 0.7‰). The magnitude of the enrichment factor...

Université de Neuchâtel

Use of stable isotope analysis to assess biodegradation of volatile organic compounds in the unsaturated subsurface

Bouchard, Daniel ; Hunkeler, Daniel (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2007 ; 1914.

The general aim of the project is to evaluate the feasibility of using compound-specific isotope analysis (CSIA) to assess biodegradation of petroleum hydrocarbons in the unsaturated zone. The first objective was to quantify the isotope enrichment factors during biodegradation of several volatile organic compounds (VOCs) commonly found on petroleum hydrocarbon contaminated sites. These microcosm...