Compound-Specific Isotope Analysis (CSIA) Application for Source Apportionment and Natural Attenuation Assessment of Chlorinated Benzenes

摘要

In light of the complex management of chlorobenzene (CB) contaminated sites, at whichuda hydraulic barrier (HB) for plumes containment is emplaced, compound-specific stable isotopeudanalysis (CSIA) has been applied for source apportionment, for investigating the relation betweenudthe upgradient and downgradient of the HB, and to target potential CB biodegradation processes.udThe isotope signature of all the components potentially involved in the degradation processes has beenudexpressed using the concentration-weighted average 13C of CBs + benzene (13Csum). Upgradient ofudthe HB, the average 13Csum of 25.6‰and 29.4‰were measured for plumes within the easternudand western sectors, respectively. Similar values were observed for the potential sources, withud13Csum values of 26.5‰for contaminated soils and 29.8‰for the processing water pipeline inudthe eastern and western sectors, respectively, allowing for apportioning of these potential sources toudthe respective contaminant plumes. For the downgradient of the HB, similar CB concentrations butudenriched 13Csum values between 24.5‰and 25.9‰were measured. Moreover, contaminatedudsoils showed a similar 13Csum signature of 24.5‰, thus suggesting that the plumes likely originateudfrom past activities located in the downgradient of the HB. Within the industrial property, significantud13C enrichments were measured for 1,2,4-trichlorobenzene (TCB), 1,2-dichlorobenzene (DCB),ud1,3-DCB, and 1,4-DCBs, thus suggesting an important role for anaerobic biodegradation. Furtheruddegradation of monochlorobenzene (MCB) and benzene was also demonstrated. CSIA was confirmedudto be an effective approach for site characterization, revealing the proper functioning of the HB anduddemonstrating the important role of natural attenuation processes in reducing the contaminationudupgradient of the HB.