Evaluation of carbon isotope fractionation during anaerobic reductive dehalogenation of chlorinated and brominated benzenes

In Situ Microbial Degradation of PBDEs in Sediments from an E-Waste Site as Revealed by Positive Matrix Factorization and Compound-Specific Stable Carbon Isotope Analysis

“…16 Therefore, CSIA can provide evidence of the environmental attenuation of pollutants at different temporal and spatial scales when degradation products cannot be detected. 17 Thus far, CSIA has been widely employed to assess the in situ microbial degradation of chlorinated ethenes, 18 halogenated benzene, 19 and chlorpyrifos. 20 Laboratory studies have also shown the potential use of CSIA to trace the fate of PBDEs during photochemical transformation 21 and biotransformation in fish.…”

Isotope Fractionation (δ13C, δ15N) in the Microbial Degradation of Bromoxynil by Aerobic and Anaerobic Soil Enrichment Cultures

“…Carbon–halogen bond cleavage is expected to be accompanied by a normal isotope effect with a similar magnitude for C–Cl and C–Br bonds (1.057 and 1.043, respectively). ,, Carbon isotope effects are widely documented for the microbial reductive dehalogenation of aliphatic compounds and present AKIE in this magnitude. ,, Fewer studies have reported on the carbon isotope effect for the microbial reductive dehalogenation of aromatic compounds. Here, reported values vary ε bulk from −0.8 ± 0.1‰ to −6.3 ± 0.2‰ (AKIE from 1.005 to 1.0039) in mono-, di-, and trichlorinated benzenes, − down to undetected in tetrabrominated benzene . Thus, empirical data point toward lower carbon isotope effects in aromatic systems.…”

“…Here, reported values vary ε bulk from −0.8 ± 0.1‰ to −6.3 ± 0.2‰ (AKIE from 1.005 to 1.0039) in mono-, di-, and trichlorinated benzenes, 56−58 down to undetected in tetrabrominated benzene. 59 Thus, empirical data point toward lower carbon isotope effects in aromatic systems. In addition to the larger number of carbon atoms in bromoxynil (seven) versus bromobenzenes (six) and the formerly reported brominated aliphatics (two) that lower the measured effect, the undetected carbon isotope effect may also be attributed to slow rate-determining steps prior to catalysis, such as slower transport through the cell membrane of the larger molecule.…”

Photodegradation of pesticides using compound-specific isotope analysis (CSIA): a review

“…CSIA has been used to evaluate the biodegradation of HCB and monitoring the in situ microbial reductive dehalogenation of highly halogenated benzene by carbon isotope fractionation. 72 Triadimefon (TDF) [(R,S)-1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one] is a chiral systemic broadspectrum 1,2,4-triazole fungicide and organochlorine pesticide used for controlling plant diseases and insect pests. More than 30% of pesticides are chiral.…”

“…CSIA has been used to evaluate the biodegradation of HCB and monitoring the in situ microbial reductive dehalogenation of highly halogenated benzene by carbon isotope fractionation. 72 …”