Benzene oxidation under sulfate-reducing conditions in columns simulating in situ conditions
The oxidation of benzene under sulfate-reducing conditions was examined in column and batch experiments under close to in situ conditions. Mass balances and degradation rates for benzene oxidation were determined in four sand and four lava granules filled columns percolated with groundwater from an anoxic benzene-contaminated aquifer. The stoichiometry of oxidized benzene, produced hydrogen carbonate and reduced sulfate correlated well with the theoretical equation for mineralization of benzene with sulfate as electron acceptor. Mean retention times of water in four columns were determined using radon (222Rn) as tracer. The retention times were used to calculate average benzene oxidation rates of 8–36 μM benzene day−1. Benzene-degrading, sulfide-producing microcosms were successfully established from sand material of all sand filled columns, strongly indicating that the columns were colonized by anoxic benzene-degrading microorganisms. In general, these data indicate a high potential for Natural Attenuation of benzene under sulfate-reducing conditions at the field site Zeitz. In spite of this existing potential to degrade benzene with sulfate as electron acceptor, the benzene plume at the field site is much longer than expected if benzene would be degraded at the rates observed in the column experiment, indicating that benzene oxidation under sulfate-reducing conditions is limited in situ.
KeywordsBenzene Degradation Natural attenuation Sulfate-reducing conditions
This work is integrated in the internal research and development program of the UFZ as well as the SAFIRA I project. The authors thank Werner Kletzander, Ralf Trabitzsch and Jörg Ahlheim of the Department of Groundwater Remediation for column sampling and organizational help, and Dietmar Hähnel for analyzing BTEX, sulfide, sulfate and carbonate during the column experiment. Special thanks is addressed to Stephanie Hinke for preparing culture media and analyzing samples of sulfide and benzene during the microcosm experiment.
- Aronson D, Howard PH (1997) Anaerobic degradation of organic chemicals in groundwater: a summary of field and laboratory studies. Final Report. Environmental Science Center, Syracus Research Cooperation, New York, pp. 244Google Scholar
- Atlas RM (1981) Microbial degradation of petroleum hydrocarbons: an environmental perspective. Microbiol Rev 45:180–209Google Scholar
- Burland SM, Edwards EA (1999) Benzene biodegradation linked to nitrate reduction. Appl Environ Microbiol 65:529–533Google Scholar
- Dean BJ (1985) Recent findings on the genetic toxicology of benzene, toluene, xylenes and phenols. Mutat Res 145:153–181Google Scholar
- Edwards EA, Grbic-Galic D (1992) Complete mineralization of benzene by aquifer microorganisms under strictly anaerobic conditions. Appl Environ Microbiol 58:2663–2666Google Scholar
- Grbic-Galic D, Vogel TM (1987) Transformation of toluene and benzene by mixed methanogenic cultures. Appl Environ Microbiol 53:254–260Google Scholar
- Griebler C, Mindl B, Slezak D, Geiger-Kaiser M (2002) Distribution pattern of attached and suspended bacteria in pristine and contaminated shallow aquifers studies with an in situ sediment exposure. Aquat Microb Ecol 28:117–129Google Scholar
- Lovley DR, Coates JD, Woodward JC, Phillips EJP (1995) Benzene oxidation coupled to sulfate reduction. Appl Environ Microbiol 61:953–958Google Scholar
- Van Agteren MH, Keuning S, Janssen DB (1998) Handbook on biodegradation and biological treatment of hazardous organic compounds. Kluwer Academic Publishers, DordrechtGoogle Scholar
- Weiner JM, Lovley DR (1998) Anaerobic benzene degradation in petroleum-contaminated aquifer sediments after inoculation with a benzene-oxidizing enrichment. Appl Environ Microbiol 64:775–778Google Scholar
- Wiedemeier TH, Newell CJ, Rifai HS, Wilson JT (1999) Natural attenuation of fuels and chlorinated solvents in the subsurface. Wiley, New YorkGoogle Scholar