Carbon isotope fractionation during anaerobic biodegradation of toluene: Implications for intrinsic bioremediation
Carbon isotope fractionation produced by anaerobic biodegradation of toluene was evaluated in laboratory experiments under both methanogenic and sulfate-reducing conditions. A small ({approximately}2{per_thousand}) but highly reproducible {sup 13}C-enrichment in the residual toluene at advanced stages of microbial transformation was observed in both cultures. The maximum isotopic enrichment observed in the residual toluene was +2.0{per_thousand} and +2.4{per_thousand} for the methanogenic and sulfate-reducing cultures, respectively, corresponding to isotopic enrichment factors ({epsilon}) of {minus}0.5 and {minus}0.8. Because the accuracy and reproducibility associated with gas chromatograph-combustion-isotope ratio mass spectrometry (GC/C/IRMS) is {+-}0.5{per_thousand}, delineating which of these two terminal electron-accepting processes (TEAP) is responsible for the biodegradation of toluene at field sites will not be possible. However, the potential does exist to use compound-specific isotope analysis (CSIA), in conjunction with other methodologies, as a means of validating advanced stages of intrinsic bioremediation in anaerobic systems. Caution is urged that relating this small ({approximately}2{per_thousand}) fractionation to biodegradation at complex field sites will prove a challenge.
- Research Organization:
- Univ. of Toronto, Ontario (CA)
- OSTI ID:
- 20023218
- Journal Information:
- Environmental Science and Technology, Vol. 34, Issue 5; Other Information: PBD: 1 Mar 2000; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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