Benzene oxidation under sulfate-reducing conditions in columns simulating in situ conditions

Abstract

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.

Protein-SIP enables time-resolved analysis of the carbon flux in a sulfate-reducing, benzene-degrading microbial consortium

“…This discrepancy can be explained by the heterogeneous material of the samples and connected abiotic processes like precipitation of sulfide with iron ions stemming from Carbon flux in a sulfate-reducing, benzene-degrading microbial consortium M Taubert et al the sediment. Such effects were also observed in previous studies (Vogt et al, 2007). The carbon isotope composition of CO 2 could only be determined in the 13 C-benzene cultivation due to the high amount of 13 CO 2 in the 13 C-carbonate cultivation (Supplementary Figure S4).…”

“…The columns are 190 cm in length and 27.3 cm in diameter, and are made of stainless steel. The percolating groundwater contains on an average 300 mM benzene and 4 mM sulfate (Vogt et al, 2007). Since 2007, benzene has been continuously degraded under sulfate-reducing conditions in all four columns.…”

“…Subsequently, groundwater was exchanged inside an anaerobic glove box (gas atmosphere 95% nitrogen and 5% hydrogen; Coy Laboratory Products Inc., Grass Lake, MI USA) by anoxic mineral salt medium, as described in Vogt et al (2007), containing 20 mM sulfate as electron acceptor.…”

Degradation of BTEX by anaerobic bacteria: physiology and application

“…Moreover, anaerobic benzene degradation with Fe(III) as the electron acceptor was stimulated by humic substances, which serve as electron shuttle compounds between Fe(III)-reducing bacteria and insoluble Fe(III) oxides . With sulfate as the electron acceptor, anaerobic benzene degradation has been found in a column study (Vogt et al 2007), in microcosms Lovley et al 1995;Coates et al 1996a, b;Kazumi et al 1997;Anderson and Lovley 2000), and in enrichments (Phelps et al 1996(Phelps et al , 1998Ulrich and Edwards 2003;Musat and Widdel 2007;Herrmann et al 2008;Kleinsteuber et al 2008;Laban et al 2009). Under methanogenic conditions, anaerobic benzene degradation has been demonstrated in microcosms (Kazumi et al 1997; and in enrichments (Vogel and Grbic-Galic 1986;Grbic-Galic and Vogel 1987;Ulrich and Edwards 2003;Chang et al 2005).…”

Stable Isotope Probing Approaches to Study Anaerobic Hydrocarbon Degradation and Degraders

“…A sulfate-reducing benzene-degrading freshwater enrichment culture was intensively investigated, which was originally enriched in a sand-or lava-filled column system percolated with benzene-containing sulfidic groundwater taken from a contaminated aquifer [Vogt et al, 2007]. A specific feature of this culture is its essential attachment to sand particles , hindering on the one hand a specific enrichment of benzene-assimilating organisms, but reflecting on the other hand a native anaerobic benzene-degrading microbial community as most microorganisms in aquifers are sessile [Griebler and Lueders, 2009].…”