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Estimation of Rates of Aerobic Hydrocarbon Biodegradation by Simulation of Gas Transport in the Unsaturated Zone
Author(s) -
Lahvis Matthew A.,
Baehr Arthur L.
Publication year - 1996
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/96wr00805
Subject(s) - hydrocarbon , carbon dioxide , environmental remediation , biodegradation , environmental chemistry , environmental science , vadose zone , groundwater remediation , chemistry , total petroleum hydrocarbon , oxygen , degradation (telecommunications) , environmental engineering , soil science , contamination , soil contamination , soil water , ecology , organic chemistry , biology , telecommunications , computer science
The distribution of oxygen and carbon dioxide gases in the unsaturated zone provides a geochemical signature of aerobic hydrocarbon degradation at petroleum product spill sites. The fluxes of these gases are proportional to the rate of aerobic biodegradation and are quantified by calibrating a mathematical transport model to the oxygen and carbon dioxide gas concentration data. Reaction stoichiometry is assumed to convert the gas fluxes to a corresponding rate of hydrocarbon degradation. The method is applied at a gasoline spill site in Galloway Township, New Jersey, to determine the rate of aerobic degradation of hydrocarbons associated with passive and bioventing remediation field experiments. At the site, microbial degradation of hydrocarbons near the water table limits the migration of hydrocarbon solutes in groundwater and prevents hydrocarbon volatilization into the unsaturated zone. In the passive remediation experiment a site‐wide degradation rate estimate of 34,400 g yr −1 (11.7 gal. yr −1 ) of hydrocarbon was obtained by model calibration to carbon dioxide gas concentration data collected in December 1989. In the bioventing experiment, degradation rate estimates of 46.0 and 47.9 g m −2 yr −1 (1.45 × 10 −3 and 1.51 × 10 −3 gal. ft. −2 yr −1 ) of hydrocarbon were obtained by model calibration to oxygen and carbon dioxide gas concentration data, respectively. Method application was successful in quantifying the significance of a naturally occurring process that can effectively contribute to plume stabilization.