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Use of Aerobic and Anaerobic Microcosms to Assess BTEX Biodegradation in Aquifers
Author(s) -
Salanitro J.P.,
Wisniewski H.L.,
Byers D.L.,
Neaville C.C.,
Schroder R.A.
Publication year - 1997
Publication title -
groundwater monitoring and remediation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 47
eISSN - 1745-6592
pISSN - 1069-3629
DOI - 10.1111/j.1745-6592.1997.tb00596.x
Subject(s) - btex , microcosm , environmental chemistry , biodegradation , aquifer , chemistry , anaerobic exercise , subsoil , environmental science , groundwater , soil water , soil science , xylene , geology , benzene , physiology , geotechnical engineering , organic chemistry , biology
The natural attenuation of soluble aromatic hydrocarbons (BTEX) in aquifer plumes is controlled by several factors, including the concentration of BTEX and dissolved oxygen (DO) or other electron acceptors (EA), hydrogeological factors (dispersion, dilution, aquifer reaeration rate), and the presence of BTEX‐degrading microbes. We have investigated three laboratory soil and/or well water systems (aerobic, anaerobic, and chronic low DO) which may represent field plume conditions. Microcosm prepared with sufficient DO always degraded hydrocarbons ( 10,000 ppb) at high rates ( 0.10/d) with no lag phase. Experimental simulations of chronic low DO were performed in a pressure transducer‐controlled respirometer in which O 2 was maintained at constant low levels (e.g., 0.2 to 2 mg/L). BTX also biodegraded rapidly (0.3 to 0.7/d) at all DO levels. These results suggest that plumes which appear to have low DO but continuous O 2 infiltration significantly bioattenuate hydrocarbons. The anaerobic biodegradation potential of BTEX was determined in microcosms prepared with subsoil or well water samples amended with NO 3 ‐ , Fe ‐3 , SO 4 ‐2 , or no added EA. Well water from the “aerobic” or “anaerobic” portions of one site plume showed losses in BTEX, but there was no correlation between the presence of reduced EA and degradation. Anaerobic slurries prepared from subsoil of another site showed a significant decrease (0.02 to 0.25/d) in BTEX with lag times of 0 to 40 days. Reduced gases (CH 4 , H 2 S, H 2 ) were not produced, but high concentrations of soil‐bound Fe +2 formed, suggesting that Fe +3 may have been a predominant anaerobic EA. These data indicate that the presumed consumption/reduction of anaerobic EA may not always be coupled to BTEX losses in ground water plumes.