HR: 0830h
AN: H21D-0850    [PDF]
TI: Hydraulic conductivity dependency of biodegradation of fuel hydrocarbon contaminants in a natural attenuation field site
AU: * Lu, G
EM: gplu@lbl.gov
AF: Lawrence Berkeley National Laboratory, MS 90-1116, 1 Cylcotron Road, Berkeley, CA 94720 United States
AU: Zheng, C
EM: czheng@ua.edu
AF: University of Alabama, Department of Geological Sciences, 202 Bevil Building, Tuscaloosa, AL 35487 United States
AB: Two biodegradation models are developed to represent natural attenuation of fuel-hydrocarbon contaminants as observed in a comprehensive natural-gradient tracer test in a heterogeneous aquifer on the Columbus Air Force Base in Mississippi. The first, a first-order mass loss model, describes the irreversible losses of BTEX and its individual components, i.e., benzene(B), toluene (T), ethyl benzene (E), and xylene(X). The second, a pathway model, describes sequential degradation pathways for BTEX utilizing multiple electron acceptors, including oxygen, nitrate, iron and sulfate, and via methanogenesis. The heterogeneous aquifer is represented by multiple hydraulic conductivity (K) zones delineated on the basis of numerous flowmeter K measurements. A direct propagation artificial neural network (DPN) is used as an inverse modeling tool to estimate the biodegradation rates associated with each of the K zones. In both the mass loss model and the pathway model, the biodegradation rate constants show an increasing trend with the hydraulic conductivity. The finding of correlation between biodegradation kinetics and hydraulic conductivity distribution is of general interest and relevance to characterization and modeling of natural attenuation of hydrocarbons in other petroleum-product contaminated sites.
DE: 1045 Low-temperature geochemistry
DE: 1800 HYDROLOGY
DE: 1832 Groundwater transport
DE: 2753 Numerical modeling
DE: 3210 Modeling
SC: Hydrology [H]
MN: 2003 Fall Meeting