Investigating pathways of hydrocarbon biodegradation and metal release in anaerobic environments

拟议的研究计划的目的是调查微生物地球化学过程，管理石油烃类的生物降解和流动性的金属在厌氧条件下。甲烷生成是大多数厌氧环境中的主要过程。对这一基本过程的全面了解将有助于制定更好的战略，以管理加拿大受污染的地下环境，如尾矿池、淹没土壤和沉积物、湿地和含水层。北方阿尔伯塔在沥青提取过程中产生了大量的油砂尾矿。与油砂尾矿相关的环境问题包括存在碳氢化合物等有机污染物;排放温室气体（GHG）;尾矿固结缓慢;以及从尾矿池回收孔隙水用于沥青提取过程中的回收率低。我的研究的长期目标是发现为这些问题提供解决方案所需的基本科学知识。我已经发现，“不稳定”的碳氢化合物（即，正构烷烃和单芳烃）生物降解为甲烷，产生温室气体。然而，尾矿中的碳氢化合物的主要部分是抗降解的异烷烃和环烷烃。最近，我观察到，某些异构烷烃最终会降解产甲烷条件下经过一段长时间的驯化期。这些观察结果使我提出了一个调查的生物降解性的柠檬酸烃（异构和环烷烃）和它们的降解途径在油砂尾矿产甲烷条件下。这些结果将促进我们对缺氧环境中碳氢化合物降解性的了解，并使我能够扩展我发表的动力学模型，该模型预测尾矿池的温室气体排放，包括有关非柠檬酸类碳氢化合物的新信息，从而改进我们对温室气体排放的预测。 ** 金属从尾矿池迁移到地下含水层可能影响地下水质量，并可能污染地下水与地表水交汇的水体，如阿萨巴斯卡河。此外，移动的金属/准金属可以从下面的成熟细尾矿迁移到底坑湖的上覆盖水。我观察到砷，钒和一些过渡金属的浓度在尾矿孔隙水甲烷化过程中增加。因此，我建议对尾矿库孔隙水中金属的增溶机理进行全面的研究。我将集中精力确定不同形式的金属（氧化还原金属形态），在固相和液相中，在整个甲烷生成过程中铁矿物的微生物转化。这一新知识对于评估坑底湖的可持续性和健康状况至关重要;这是回收尾矿池的一项潜在战略。

The proposed research program is designed to investigate biogeochemical processes that govern biodegradation of petroleum hydrocarbons and mobility of metals under anaerobic conditions. Methanogenesis is the dominant process in most anaerobic environments. Complete understanding of this fundamental process will help devise better strategies for management of contaminated subsurface environments in Canada such as tailings ponds, submerged soils and sediments, wetlands, and aquifers.******Enormous volumes of oil sands tailings are produced in northern Alberta during bitumen extraction process. Environmental issues associated with oil sands tailings include presence of organic contaminants such as hydrocarbons; emission of greenhouse gases (GHG); slow consolidation of tailings; and poor recovery of porewater from tailings ponds for re-use in the bitumen extraction process. The long term goal of my research is to discover the basic scientific knowledge necessary to provide solutions to these issues.******I have discovered that `labile' hydrocarbons (i.e., n-alkanes and monoaromatics) in tailings ponds biodegrade into CH4, producing GHG. However, a major portion of hydrocarbons in tailings are iso- and cyclo-alkanes that resist degradation. Recently, I have observed that certain iso-alkanes will eventually degrade under methanogenic conditions following a long acclimation period. These observations have led me to propose an investigation into the biodegradation of recalcitrant hydrocarbons (iso- and cyclo-alkanes) and their degradation pathways in oil sands tailings under methanogenic conditions. The results will advance our knowledge about the degradability of hydrocarbons in anoxic environments and allow me to expand my published kinetic model that predicts GHG emissions from tailings ponds to include new information about recalcitrant hydrocarbons, thereby refining our predictions of GHG emissions. ******Metal transport from tailings ponds to underlying aquifers can affect groundwater quality and can contaminate water bodies where groundwater meets the surface water such as in the Athabasca River. In addition, mobile metals/metalloids can migrate from underlying mature fine tailings into the overlying cap water in end pit lakes. I have observed that concentration of arsenic, vanadium and some transition metals in tailings porewater have increased during methanogenesis. I therefor propose a comprehensive investigation into the mechanism of metal solubilization in tailings pond porewater. I will focus my efforts on determining the different forms of metals (redox metal speciation), in both solid and liquid phases, during the microbial transformation of iron minerals throughout the process of methanogenesis . This new knowledge is essential for the assessment of the sustainability and health of end-pit lakes; a potential strategy for reclaiming tailings ponds.*****