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Use of a reactive gas transport model to determine rates of hydrocarbon biodegradation in unsaturated porous media

November 1, 1995

A mathematical model is presented that simulates the transport and reaction of any number of gaseous phase constituents (e.g. CO2, O2, N2, and hydrocarbons) in unsaturated porous media. The model was developed as part of a method to determine rates of hydrocarbon biodegradation associated with natural cleansing at petroleum product spill sites. The one-dimensional model can be applied to analyze data from column experiments or from field sites where gas transport in the unsaturated zone is approximately vertical. A coupled, non-Fickian constitutive relation between fluxes and concentration gradients, together with the capability of incorporating heterogeneity with respect to model parameters, results in model applicability over a wide range of experimental and field conditions. When applied in a calibration mode, the model allows for the determination of constituent production/consumption rates as a function of the spatial coordinate. Alternatively, the model can be applied in a predictive mode to obtain the distribution of constituent concentrations and fluxes on the basis of assumed values of model parameters and a biodegradation hypothesis. Data requirements for the model are illustrated by analyzing data from a column experiment designed to determine the aerobic degradation rate of toluene in sediments collected from a gasoline spill site in Galloway Township, New Jersey.

Citation Information

Publication Year 1995
Title Use of a reactive gas transport model to determine rates of hydrocarbon biodegradation in unsaturated porous media
DOI 10.1029/95WR02077
Authors Arthur L. Baehr, Ronald J. Baker
Publication Type Article
Publication Subtype Journal Article
Series Title Water Resources Research
Index ID 70185316
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program