Characterization of physical, chemical and microbial processes related to phytoremediation of petroleum contamination in a shallow fractured bedrock system

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There are an estimated 30,000 brownfield sites across Canada, many of which are located near to or within developed regions of urban landscapes. Brownfield redevelopment has been identified as an important factor in revitalizing inner city areas and preventing development of greenfield lands. However, redevelopment can stagnate as a result of logistical considerations and/or costs associated with successful remediation. Conventional remediation are often not feasible due to site-specific characteristics or proximity to residential areas. As such, development of new remediation methods is necessary to promote redevelopment of these underutilized lands. BP Canada Energy Group ULC retains environmental liability at a historical manufacturing facility ("the Site") in Guelph, Ontario, overlying the regional bedrock aquifer used for water supply. The Site was planted with hybrid poplar (Populus x Canadensis) approximately 5 years ago as a remedial strategy for elevated concentrations of toluene in groundwater. The project is an ideal field demonstration site to apply scientific developments over the past two decades, primarily in the areas of contaminant transport and fate in fractured sedimentary bedrock and genetic-based characterization of toluene biodegradation and the ecology and functionality of the plant microbiome, to evaluate the performance of the phytoremediation system in a manner that is quantitative, mechanistic, and will yield predictive rates of toluene mass removal. The proposed research is highly interdisciplinary and requires a multiple lines of evidence approach because of the number of abiotic and biotic processes, occurring in the saturated and vadose zones as well as the plant roots and above-ground tissues, that have the potential to affect source-zone residual mass attenuation and the long term evolution of the dissolved-phased plume. The novelty and importance of this work lies in elucidating the specific ways in which the plants change or augment the natural toluene attenuation processes in a fractured sedimentary bedrock aquifer and in providing a scientifically robust framework for risk management and remedial options analysis for an urban contaminated site in the Canadian context.