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

加拿大各地估计有 30,000 个棕地，其中许多位于城市景观发达地区附近或之内。棕地再开发已被确定为振兴内城区和阻止绿地开发的重要因素。然而，由于后勤考虑和/或与成功修复相关的成本，重建可能会停滞。由于场地特定特征或靠近居民区，传统的修复通常不可行。因此，有必要开发新的修复方法来促进这些未充分利用土地的再开发。 BP 加拿大能源集团 ULC 在安大略省圭尔夫市的一家历史悠久的制造工厂（“工厂”）保留环境责任，该工厂覆盖用于供水的区域基岩含水层。大约 5 年前，该场地种植了杂交杨树（杨树 x 加拿大杨树），作为地下水中甲苯浓度升高的补救策略。该项目是应用过去二十年科学发展的理想现场示范点，主要是在裂隙沉积基岩中的污染物迁移和归宿、甲苯生物降解的基因表征以及植物微生物组的生态和功能领域，以定量、机械的方式评估植物修复系统的性能，并将产生甲苯质量去除的预测率。拟议的研究是高度跨学科的，需要采用多种证据方法，因为在饱和区和渗流区以及植物根和地上组织中发生的非生物和生物过程的数量，有可能影响源区残余质量衰减和溶解相羽流的长期演化。这项工作的新颖性和重要性在于阐明植物改变或增强裂隙沉积基岩含水层中甲苯自然衰减过程的具体方式，并为加拿大城市污染场地的风险管理和补救方案分析提供科学可靠的框架。

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.