Professor, Dept. of Civil Engineering
University of Toronto
Dr Elodie Passeport is cross-appointed in the departments of Civil Engineering, and Chemical Engineering and Applied Chemistry, and a Canada Research Chair in Environmental Engineering and Stable Isotopes. She did her PhD at AgroParisTech and Irstea in France. Dr Passeport did a postdoc at UC-Berkeley in the Plant and Microbial Biology department, and a second one at the University of Toronto, in the Earth Sciences department. Her research group studies the fate and removal of contaminants from water, in natural and engineered environments. Her research is experimental and involves lab and field studies, and the development of analytical methods to determine concentrations and stable isotope signatures of organic contaminants.
PLATFORM PRESENTER – Contaminated Sediments
Coupling of High Resolution Pore Water Sampling and Compound Specific Isotope Analysis to Monitor Sediment Natural Attenuation
Monitoring the natural recovery of contaminated sediments requires the use of techniques that can provide definitive evidence of in situ contaminant degradation. In contaminated groundwater, Compound Specific Isotope Analysis (CSIA) is widely utilized to study the fate of organic contaminants. To date, however, no method is available to obtain CSIA samples at a fine (cm) spatial scale across the sediment–surface water interface (SWI), a key boundary for discharge of contaminated groundwater to surface water. In this research, a passive diffusion sampler, called “peeper”, was combined with CSIA 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. Laboratory tests demonstrated the compatibility of this passive sampler with CSIA of benzene, toluene, MCB, and 1,2-dichlorobenzene at field-relevant concentrations (0.1–5 mg L–1). Results demonstrated that physical diffusion across, and adsorption onto the peeper membrane did not alter the carbon isotope values (±0.5‰). The combined application of peeper and CSIA at a contaminated field site 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. These results provide multiple lines of evidence for in situ reductive dechlorination of MCB to benzene. 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.