thumbnail

Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes

Journal of Contaminant Hydrology
By: , , , , , and 
https://doi.org/10.1016/j.jconhyd.2011.04.003

Links

Abstract

High resolution direct-push profiling over short vertical distances was used to investigate CH4 attenuation in a petroleum contaminated aquifer near Bemidji, Minnesota. The contaminant plume was delineated using dissolved gases, redox sensitive components, major ions, carbon isotope ratios in CH4 and CO2, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in δ13CCH4 from an average of − 57.6‰ (± 1.7‰) in the methanogenic zone to − 39.6‰ (± 8.7‰) at 105 m downgradient, strongly suggest CH4 attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5 m below the water table suggesting that transport of O2 across the water table is leading to aerobic degradation of CH4 at this interface. Dissolved N2 concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O2 through aerobic degradation of CH4 or other hydrocarbons. Multivariate and cluster analysis were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the infiltration of O2 rich recharge water were important O2 transport mechanisms.

Publication type Article
Publication Subtype Journal Article
Title Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes
Series title Journal of Contaminant Hydrology
DOI 10.1016/j.jconhyd.2011.04.003
Volume 125
Issue 1-4
Year Published 2011
Language English
Publisher Elsevier
Contributing office(s) Toxic Substances Hydrology Program
Description 13 p.
First page 13
Last page 25
Google Analytic Metrics Metrics page
Additional publication details