The Effects of LNAPL Biodegradation Products on Electrical Conductivity Measurements

Field geophysical studies have identified anomalously high conductivities in and below the free product zone at many sites with aged contamination by light, non-aqueous phase liquids (LNAPL). Laboratory experiments were conducted to test the hypothesis that these anomalously high conductivities can result from products of LNAPL biodegradation. Soil from a hydrocarbon-impacted site with anomalously high conductivities was washed repeatedly to remove soluble constituents, recontaminated with diesel fuel (DF), and the pores filled with water to simulate a saturated smear zone. Nutrients were provided at levels observed at the site, which resulted in anaerobic conditions due to DF biodegradation. Within 120days, the increase in specific conductivity from microbial activity was 2,100μS∕cm, caused by an increase in total dissolved solids (DS) of over 1,700mg∕L. The increase in DS was due to mineral (mostly carbonate) dissolution and to the production of organic acids and biosurfactants. Under aerobic conditions...

[1]  R. Eganhouse,et al.  Crude oil in a shallow sand and gravel aquifer—II. Organic geochemistry , 1993 .

[2]  Donald I. Siegel,et al.  Crude oil in a shallow sand and gravel aquifer-III , 1993 .

[3]  Estella A. Atekwana,et al.  Geophysical Discovery of a New LNAPL Plume at the Former Wurtsmith AFB, Oscoda, Michigan , 1997 .

[4]  Robert P. Eganhouse,et al.  THE GEOCHEMICAL EVOLUTION OF LOW-MOLECULAR-WEIGHT ORGANIC ACIDS DERIVED FROM THE DEGRADATION OF PETROLEUM CONTAMINANTS IN GROUNDWATER , 1994 .

[5]  Robert P. Eganhouse,et al.  Transformation of Monoaromatic hydrocarbons to organic acids in anoxic groundwater environment , 1990 .

[6]  M. Gealt,et al.  Biodegradation and Bioremediation. , 1996 .

[7]  P. Bradley,et al.  Evidence for Enhanced Mineral Dissolution in Organic Acid‐Rich Shallow Ground Water , 1995 .

[8]  G. Granato,et al.  Robowell: An Automated Process for Monitoring Ground Water Quality Using Established Sampling Protocols , 1999 .

[9]  Stephen M. Testa,et al.  Restoration of petroleum-contaminated aquifers , 1990 .

[10]  I. Cozzarelli,et al.  Fate of microbial metabolites of hydrocarbons in a coastal plain aquifer: the role of electron acceptors. , 1995, Environmental science & technology.

[11]  William A. Sauck,et al.  A model for the resistivity structure of LNAPL plumes and their environs in sandy sediments , 2000 .

[12]  Estella A. Atekwana,et al.  Investigations of geoelectrical signatures at a hydrocarbon contaminated site , 2000 .