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Transport and Degradation of Toluene and o ‐Xylene in an Unsaturated Soil with Dipping Sedimentary Layers
Author(s) -
Søvik Anne Kristine,
Alfnes Eli,
Breedveld Gijs D.,
French Helen K.,
Pedersen Tor Simon,
Aagaard Per
Publication year - 2002
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2002.1809
Subject(s) - toluene , vadose zone , degradation (telecommunications) , plume , sedimentary rock , environmental chemistry , geology , soil water , chemistry , soil science , geochemistry , telecommunications , physics , organic chemistry , computer science , thermodynamics
A lysimeter trench was established at the Gardermoen delta (50 km north of Oslo, Norway) to study the flow of water and transport and degradation of aromatic jet fuel components (toluene and o ‐xylene) in the undisturbed unsaturated zone. Site investigations with ground‐penetrating radar revealed the presence of dipping sedimentary layers within the foreset unit. This study has shown that the foreset bed of the Gardermoen delta structure provided a preferential flow path for the transport of the solute plumes, but did not have dramatic effects on the degradation potential under the current conditions. The degradation potential for toluene and o ‐xylene in the unsaturated zone at Gardermoen was very high and almost all of the injected hydrocarbons were biodegraded before reaching the saturated zone. However, the horizontal displacement of the plume showed that knowledge about sedimentary structures in the unsaturated zone is important for a sufficient monitoring of contaminant transport and for remediation purposes. Carbon dioxide and O 2 were measured in situ simultaneously with extraction of water samples, and indicated aerobic biodegradation of toluene and o ‐xylene. Overall, first‐order degradation coefficients were calculated to be in the range of 0.19 to 0.21 d −1 and 0.10 to 0.11 d −1 for toluene and o ‐xylene, respectively.