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Field evidence for geophysical detection of subsurface zones of enhanced microbial activity
Author(s) -
Atekwana Eliot A.,
Atekwana Estella,
Legall Franklyn D.,
Krishnamurthy R. V.
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021576
Subject(s) - biogeochemistry , conductivity , dissolved organic carbon , geology , nitrate , manganese , sulfate , aquifer , hydrocarbon , environmental chemistry , electrical resistivity and conductivity , soil science , total organic carbon , mineralogy , groundwater , chemistry , geotechnical engineering , electrical engineering , organic chemistry , engineering
Geochemical data from closely spaced vertical intervals in a hydrocarbon‐impacted aquifer were used to assess the relationship between bulk conductivity and zones of enhanced microbial activity. The bulk conductivity was measured using in situ vertical resistivity probes. Microbial activity was verified using terminal electron acceptors (nitrate, sulfate, iron, and manganese), dissolved inorganic carbon (DIC), and major ion chemistry. Peaks in bulk conductivity in the aquifer overlapped with zones where nitrates and sulfates were depleted, total petroleum hydrocarbon, iron, manganese, dissolved ions, and DIC were elevated, suggesting a link between higher electrical conductivity and zones of enhanced microbial activity stimulated by the presence of hydrocarbon. Thus the subsurface expression of microbial activity is apparently recorded in the bulk conductivity measurements. Our results argue for combining geophysics with biogeochemistry studies to delineate subsurface zones of enhanced microbial activity.