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C and N isotope fractionation during biodegradation of the pesticide metabolite 2,6-dichlorobenzamide (BAM): Potential for environmental assessments.
Environ. Sci. Technol. 46, 1447-1454 (2012)
2,6-Dichlorobenzamide (BAM) is a metabolite of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), and a prominent groundwater contaminant. Observable compound-specific isotope fractionation during BAM formation-through transformation of dichlobenil by Rhodococcus erythropolis DSM 9685-was small. In contrast, isotope fractionation during BAM degradation-with Aminobacter sp. MSH1 and ASI1, the only known bacterial strains capable of mineralizing BAM-was large, with pronounced carbon (ε(C) = -7.5‰ to -7.8‰) and nitrogen (ε(N) = -10.7‰ to -13.5‰) isotopic enrichment factors. BAM isotope values in natural samples are therefore expected to be dominated by the effects of its degradation rather than formation. Dual isotope slopes Δ (=Δδ(15)N/Δδ(13)C ≈ ε(N)/ε(C)) showed only small differences for MSH1 (1.75 ± 0.03) and ASI1 (1.45 ± 0.03) suggesting similar transformation mechanisms of BAM hydrolysis. Observations are in agreement with either a tetrahedral intermediate promoted by OH(-) or H(3)O(+) catalysis, or a concerted reaction mechanism. Therefore, owing to consistent carbon isotopic fractionation, isotope shifts of BAM can be linked to BAM biodegradation, and may even be used to quantify degradation of this persistent metabolite. In contrast, nitrogen isotope values may be rather indicative of different sources. Our results delineate a new approach to assessing the fate of BAM in the environment.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
benzene biodegradation; herbicide dichlobenil; microbial dechlorination; organic contaminants; degradation pathways; carbon; soils; transformation; mineralization; hydrolysis
Language
Publication Year
2012
HGF-reported in Year
2012
ISSN (print) / ISBN
0013-936X
e-ISSN
1520-5851
Quellenangaben
Volume: 46,
Issue: 3,
Pages: 1447-1454
Publisher
ACS
Publishing Place
Washington, DC
Reviewing status
Peer reviewed
Institute(s)
Institute of Groundwater Ecology (IGOE)
POF-Topic(s)
20403 - Sustainable Water Management
Research field(s)
Environmental Sciences
PSP Element(s)
G-504390-001
PubMed ID
22191999
WOS ID
WOS:000299864400023
Scopus ID
84856695302
Erfassungsdatum
2012-02-13