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Compound-specific isotope analysis (CSIA) evaluation of degradation of chlorinated benzenes (CBs) and benzene in a contaminated aquifer.
- Source :
-
Journal of Contaminant Hydrology . Oct2022, Vol. 250, pN.PAG-N.PAG. 1p. - Publication Year :
- 2022
-
Abstract
- Compound-specific isotope analysis (CSIA) has become a valuable tool in understanding the fate of organic contaminants at field sites. However, its application to chlorinated benzenes (CBs), a group of toxic and persistent groundwater contaminants, has received less attention. This study employed CSIA to investigate the occurrence of natural degradation of various CBs and benzene in a contaminated aquifer. Despite the complexity of the study area (e.g., installation of a sheet pile barrier and the presence of a complex set of contaminants), the substantial enrichments in δ13C values (i.e., >2‰) for all CBs and benzene across the sampling wells indicate in situ degradation of these compounds. In particular, the 13C enrichments for 1,2,4-trichlorobenzene (1,2,4-TCB) and 1,2-dichlorobenzene (1,2-DCB) display good correlations with decreasing groundwater concentrations, consistent with the effects of in situ biodegradation. Using the Rayleigh model, the extent of degradation (EoD) is estimated to be 47-99% for 1,2-DCB, and 21-73% for 1,2,4-TCB. The enrichments observed for the other CBs (1,4-DCB and chlorobenzene (MCB)) and benzene at the site are also suggestive of in situ biodegradation. Due to simultaneous degradation and production of 1,4-DCB (a major 1,2,4-TCB degradation product), MCB (from DCB degradation), and benzene (from MCB degradation), the estimation of EoD for these intermediate compounds is more complex but a modelling simulation supports in situ biodegradation of these daughter products. In particular, the fact that the δ13C values of MCB and benzene (i.e., daughter products of 1,2,4-TCB) are more enriched than the original δ13C value of their parent 1,2,4-TCB provides definitive evidence for the occurrence of in situ biodegradation of the MCB and benzene. • Fills an important gap in understanding fate of chlorinated benzenes in the field • CSIA confirms in situ biodegradation of parent contaminants 1,2,4-TCB and 1,2-DCB • CSIA and modelling suggest degradation of MCB and benzene daughter products. [ABSTRACT FROM AUTHOR]
- Subjects :
- *ISOTOPIC analysis
*BENZENE
*RAYLEIGH model
*AQUIFERS
*CHLOROBENZENE
*CUCURBITURIL
Subjects
Details
- Language :
- English
- ISSN :
- 01697722
- Volume :
- 250
- Database :
- Academic Search Index
- Journal :
- Journal of Contaminant Hydrology
- Publication Type :
- Academic Journal
- Accession number :
- 159383972
- Full Text :
- https://doi.org/10.1016/j.jconhyd.2022.104051