A simple method for calculating growth rates of petroleum hydrocarbon plumes

Ground Water
By: , and 



Consumption of aquifer Fe(III) during biodegradation of ground water contaminants may result in expansion of a contaminant plume, changing the outlook for monitored natural attenuation. Data from two research sites contaminated with petroleum hydrocarbons show that toluene and xylenes degrade under methanogenic conditions, but the benzene and ethylbenzene plumes grow as aquifer Fe(III) supplies are depleted. By considering a one‐dimensional reaction front in a constant unidirectional flow field, it is possible to derive a simple expression for the growth rate of a benzene plume. The method balances the mass flux of benzene with the Fe(III) content of the aquifer, assuming that the biodegradation reaction is instantaneous. The resulting expression shows that the benzene front migration is retarded relative to the ground water velocity by a factor that depends on the concentrations of hydrocarbon and bioavailable Fe(III). The method provides good agreement with benzene plumes at a crude oil study site in Minnesota and a gasoline site in South Carolina. Compared to the South Carolina site, the Minnesota site has 25% higher benzene flux but eight times the Fe(III), leading to about one‐sixth the expansion rate. Although it was developed for benzene, toluene, ethylbenzene, and xylenes, the growth‐rate estimation method may have applications to contaminant plumes from other persistent contaminant sources.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title A simple method for calculating growth rates of petroleum hydrocarbon plumes
Series title Ground Water
DOI 10.1111/j.1745-6584.2005.00093.x
Volume 43
Issue 6
Year Published 2005
Language English
Publisher Wiley
Contributing office(s) Toxic Substances Hydrology Program
Description 10 p.
First page 817
Last page 826
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