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 ((222)Rn) as tracer. The retention times were used to calculate average benzene oxidation rates of 8-36 microM 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.
Vogt
Carsten
C
Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany. carsten.vogt@ufz.de
Gödeke
Stefan
S
Treutler
Hanns-Christian
HC
Weiss
Holger
H
Schirmer
Mario
M
Richnow
Hans-Hermann
HH
D001554:Benzene / Q000737:chemistry*; D001639:Bicarbonates / Q000737:chemistry; D001673:Biodegradation, Environmental; D004583:Electrons; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D011886:Radon / Q000737:chemistry; D012822:Silicon Dioxide; D013431:Sulfates / Q000737:chemistry*; D013463:Sulfuric Acid Esters / Q000737:chemistry; D013997:Time Factors
D001639:Bicarbonates; D013431:Sulfates; D013463:Sulfuric Acid Esters; D012822:Silicon Dioxide; D001554:Benzene; D011886:Radon; D010100:Oxygen