title: In situ transformation of deuterated toluene and xylene to benzylsuccinic acid analogues in BTEX-contaminated aquifers.
abstract: Techniques for detecting and quantifying anaerobic transformations of benzene, toluene, ethylbenzene, and xylene (BTEX) are needed to assess the feasibility of using in situ bioremediation to treat BTEX-contaminated groundwater aquifers. Deuterated surrogates of toluene (toluene-d8) and xylene (o-xylene-d10) were injected into BTEX-contaminated aquifers during single-well push-pull tests to monitor for the in situ formation of deuterated benzylsuccinic acid (BSA-d8) and o-methyl-BSA-d10. Test solutions (250 L) containing toluene-d8 (9-22 microM) and o-xylene-d10 (4-9 microM) along with a conservative bromide tracer (1.3 mM) and nitrate (4 mM) as an electron acceptor were injected into four wells at two sites. Detection of BSA-d8 and o-methyl-BSA-d10 in groundwater samples collected from the same wells following injection unequivocally demonstrated anaerobic in situ toluene-d8 and o-xylene-d10 transformation with calculated zero-order formation rates ranging from 1.0 to 7.4 nM/day. Concurrent utilization of co-injected nitrate was rapid in all tests at both sites, with zero-order rates ranging from 13 to 39 microM/h. The field tests conducted in this study represent the first reported use of deuterated aromatic hydrocarbons to detect and quantify anaerobic BTEX transformation product formation in the subsurface.
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Reusser
authors.forename: J D
authors.initials: JD
authors.lastname: Istok
authors.forename: H R
authors.initials: HR
authors.lastname: Beller
authors.forename: J A
authors.initials: JA
authors.lastname: Field
mesh_terms: D001421:Bacteria, Anaerobic / Q000502:physiology; D001673:Biodegradation, Environmental; D001711:Biotransformation; D014050:Toluene / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism; D014992:Xylenes / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D014992:Xylenes; D014050:Toluene