Biodegradation and mineral weathering controls on bulk electrical conductivity in a shallow hydrocarbon contaminated aquifer.

Geochemical and stable carbon isotope data from closely spaced vertical intervals in a hydrocarbon-impacted aquifer were used to assess the relationship between biodegradation, mineral weathering, and enhanced bulk conductivity zones. The results show that depth zones of enhanced bulk conductivity in the contaminated aquifer had higher total dissolved solids (TDS) compared to background groundwater. The higher TDS in contaminated groundwater were due to elevated ion concentrations from enhanced mineral weathering. Depth intervals with higher concentrations of major cations overlapped with zones with higher total petroleum hydrocarbons, which were the same zones where reduction of nitrate, iron, manganese, sulfate, and methanogenesis was occurring. Hence, the zones of higher bulk conductivity may be explained by mineral weathering related to hydrocarbon biodegradation. Our results suggest that biodegradation of hydrocarbons may impart changes to the aquifer geochemistry that can be indirectly observed using geophysical techniques. We therefore argue for inclusion of geophysical investigations as part of natural attenuation assessment programs.

[1]  D. Cassidy,et al.  In Situ Rhamnolipid Production at an Abandoned Petroleum Refinery , 2002 .

[2]  A. Herczeg,et al.  Inorganic Ions as Tracers , 2000 .

[3]  Estella A. Atekwana,et al.  High Conductivities Associated With an LNAPL Plume Imaged by Integrated Geophysical Techniques , 1998 .

[4]  D. Dale Werkema,et al.  Geophysical Investigation of Vadose Zone Conductivity Anomalies at a Hydrocarbon Contaminated Site: Implications for the Assessment of Intrinsic Bioremediation , 2002 .

[5]  H. Vinegar,et al.  Induced polarization of shaly sands , 1984 .

[6]  M. H. Waxman,et al.  Electrical Conductivities in Oil-Bearing Shaly Sands , 1968 .

[7]  R. Hinchee,et al.  Monitoring in situ biodegradation of hydrocarbons by using stable carbon isotopes , 1991 .

[8]  Bruce E. Rittmann,et al.  Natural attenuation strategy for groundwater cleanup focuses on demonstrating cause and effect , 2001 .

[9]  J. Hem.  Study and Interpretation of the Chemical Characteristics of Natural Water , 1989 .

[10]  Estella A. Atekwana,et al.  In-situ apparent conductivity measurements and microbial population distribution at a hydrocarbon-contaminated site , 2004 .

[11]  E. Grossman,et al.  Bacterial production of methane and its influence on ground-water chemistry in east-central Texas aquifers , 1989 .

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

[13]  J. J. Morgan,et al.  Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters , 1970 .

[14]  M. A. Baltusis,et al.  Physical and chemical data for ground water in the Michigan basin, 1986-89 , 1990 .

[15]  L. Slater,et al.  Effects of microbial processes on electrolytic and interfacial electrical properties of unconsolidated sediments , 2004 .

[16]  D. Dale Werkema,et al.  A Versatile Windows Based Multi-Electrode Acquisition System for DC Electrical Methods Surveys , 1998 .

[17]  F. Chapelle,et al.  Temporal and spatial changes of terminal electron‐accepting processes in a petroleum hydrocarbon‐contaminated aquifer and the significance for contaminant biodegradation , 1994 .

[18]  Anthony L. Endres,et al.  Investigating the geoelectrical response of hydrocarbon contamination undergoing biodegradation , 2003 .

[19]  R. Krishnamurthy,et al.  Concentrations and isotope ratios of dissolved inorganic carbon in denitrifying environments , 1997 .

[20]  Werkema,et al.  Geoelectrical response of an aged LNAPL plume: Implications for monitoring natural attenuation , 2002 .

[21]  Silvia Rossbach,et al.  Evidence for microbial enhanced electrical conductivity in hydrocarbon‐contaminated sediments , 2004 .

[22]  Induced Polarization (Ip) Measurements Of Soils From An Aged Hydrocarbon Contaminated Site , 2003 .

[23]  I. Clark,et al.  Environmental Isotopes in Hydrogeology , 1997 .

[24]  M. Kashgarian,et al.  Combined 14C and δ13C Monitoring of in Situ Biodegradation of Petroleum Hydrocarbons , 1997 .

[25]  P. Bennett,et al.  Microbial colonization and weathering of silicates in a petroleum-contaminated groundwater , 1996 .

[26]  E. Atekwana,et al.  The relationship of total dissolved solids measurements to bulk electrical conductivity in an aquife , 2004 .

[27]  J. Bradford.  Gpr Offset Dependent Reflectivity Analysis For Characterization Of A High-Conductivity Lnapl Plume , 2003 .

[28]  Thomas Højlund Christensen,et al.  Speciation of Dissolved Iron(II) and Manganese(II) in a Groundwater Pollution Plume , 1998 .

[29]  R. Krishnamurthy,et al.  Seasonal variations of dissolved inorganic carbon and δ13C of surface waters : application of a modified gas evolution technique , 1998 .

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

[31]  D. Hunkeler,et al.  Intrinsic bioremediation of a petroleum hydrocarbon-contaminated aquifer and assessment of mineralization based on stable carbon isotopes , 1999, Biodegradation.

[32]  A. Mills,et al.  Manual of environmental microbiology. , 2007 .

[33]  M. E. Tuccillo,et al.  Iron reduction in the sediments of a hydrocarbon-contaminated aquifer , 1999 .

[34]  Estella A. Atekwana,et al.  Field evidence for geophysical detection of subsurface zones of enhanced microbial activity , 2004 .

[35]  F. Chapelle,et al.  Stable Carbon Isotopes of HCO3 in the Aquia Aquifer, Maryland: Evidence for an Isotopically Heavy Source of CO2 , 1985 .

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

[37]  M. Hamburger,et al.  A STUDY OF ACID MINE DRAINAGE USING EARTH RESISTIVITY MEASUREMENTS , 1990 .

[38]  G. E. Archie.  The electrical resistivity log as an aid in determining some reservoir characteristics , 1942 .

[39]  W. Sauck.  A Conceptual Model For The Geoelectrical Response Of Lnapl Plumes In Granular Sediments , 1998 .

[40]  Peter G. Cook,et al.  Environmental Tracers in Subsurface Hydrology , 2000 .

[41]  M. Meju,et al.  Geoelectrical investigation of old/abandoned, covered landfill sites in urban areas: model development with a genetic diagnosis approach , 2000 .

[42]  M. E. Tuccillo,et al.  Progression of natural attenuation processes at a crude-oil spill site: I. Geochemical evolution of the plume. , 2001, Journal of contaminant hydrology.