title: Sediment Monitored Natural Recovery Evidenced by Compound Specific Isotope Analysis and High-Resolution Pore Water Sampling.
abstract: Monitoring natural recovery of contaminated sediments requires the use of techniques that can provide definitive evidence of in situ contaminant degradation. In this study, a passive diffusion sampler, called "peeper", was combined with Compound Specific Isotope Analysis to determine benzene and monochlorobenzene (MCB) stable carbon isotope values at a fine vertical resolution (3 cm) across the sediment water interface at a contaminated site. Results indicated significant decrease in concentrations of MCB from the bottom to the top layers of the sediment over 25 cm, and a 3.5 ‰ enrichment in δ13C values of MCB over that distance. Benzene was always at lower concentrations than MCB, with consistently more depleted δ13C values than MCB. The redox conditions were dominated by iron reduction along most of the sediment profile. These results provide multiple lines of evidence for in situ reductive dechlorination of MCB to benzene. Stable isotope analysis of contaminants in pore water is a valuable method to demonstrate in situ natural recovery of contaminated sediments. This novel high-resolution approach is critical to deciphering the combined effects of parent contaminant (e.g., MCB) degradation and both production and simultaneous degradation of daughter products, especially benzene.
authors: Department of Earth Sciences, University of Toronto , Toronto, Ontario, M5S 3B1, Canada.
authors: Elodie
authors: E
authors: Passeport
authors: DuPont Engineering and Technology, Wilmington, Delaware 19803, United States.
authors: Richard
authors: R
authors: Landis
authors: Department of Earth Sciences, University of Toronto , Toronto, Ontario, M5S 3B1, Canada.
authors: Georges
authors: G
authors: Lacrampe-Couloume
authors: The Chemours Company, Corporate Remediation Group, Wilmington, Delaware 19899, United States.
authors: Edward J
authors: EJ
authors: Lutz
authors: DuPont Corporate Remediation Group, Wilmington, Delaware 19803, United States.
authors: E Erin
authors: EE
authors: Mack
authors: AECOM, Deepwater, New Jersey 02907, United States.
authors: Kathryn
authors: K
authors: West
authors: AECOM, Deepwater, New Jersey 02907, United States.
authors: Scott
authors: S
authors: Morgan
authors: Department of Earth Sciences, University of Toronto , Toronto, Ontario, M5S 3B1, Canada.
authors: Barbara
authors: B
authors: Sherwood Lollar
mesh_terms: D001554:Benzene; D001673:Biodegradation, Environmental; D002247:Carbon Isotopes; D004784:Environmental Monitoring; D054879:Halogenation; D014874:Water Pollutants, Chemical
chemical_list: D002247:Carbon Isotopes; D014874:Water Pollutants, Chemical; D001554:Benzene