Investigating pathways of hydrocarbon biodegradation and metal release in anaerobic environments

研究厌氧环境中碳氢化合物生物降解和金属释放的途径

• 批准号: RGPIN-2015-03942
• 负责人: Siddique, Tariq
• 金额: $ 1.6万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=678746
• 关键词: Investigating; pathways; hydrocarbon; biodegradation; metal

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.*****

拟议的研究计划旨在研究控制石油烃生物降解和厌氧条件下金属流动性的生物地球化学过程。产甲烷是大多数厌氧环境中的主要过程。全面了解这一基本过程将有助于制定更好的策略来管理加拿大受污染的地下环境，例如尾矿池、淹没土壤和沉积物、湿地和含水层。******北部生产了大量的油砂尾矿艾伯塔省在沥青提取过程中。与油砂尾矿相关的环境问题包括碳氢化合物等有机污染物的存在；温室气体（GHG）排放；尾矿固结缓慢；从尾矿库中回收孔隙水以在沥青提取过程中重新使用的情况较差。我研究的长期目标是发现解决这些问题所需的基础科学知识。******我发现尾矿池中的“不稳定”碳氢化合物（即正构烷烃和单芳烃）可生物降解为CH4，产生温室气体。然而，尾矿中的碳氢化合物的主要部分是难以降解的异构烷烃和环烷烃。最近，我观察到某些异烷烃在经过长时间的适应期后最终会在产甲烷条件下降解。这些观察结果促使我提议研究顽固性碳氢化合物（异烷烃和环烷烃）的生物降解及其在产甲烷条件下油砂尾矿中的降解途径。这些结果将增进我们对缺氧环境中碳氢化合物降解性的了解，并使我能够扩展我已发表的预测尾矿库温室气体排放的动力学模型，以包含有关顽固性碳氢化合物的新信息，从而完善我们对温室气体排放的预测。 ******金属从尾矿库到地下含水层的迁移会影响地下水质量，并可能污染地下水与地表水交汇处的水体，例如阿萨巴斯卡河。此外，移动金属/准金属可以从下面的成熟细尾矿迁移到末端坑湖的上覆盖水中。我观察到尾矿孔隙水中砷、钒和一些过渡金属的浓度在产甲烷过程中有所增加。因此，我建议对尾矿库孔隙水中金属增溶的机理进行全面的研究。我将集中精力确定在整个产甲烷过程中铁矿物的微生物转化过程中固相和液相中不同形式的金属（氧化还原金属形态）。这些新知识对于评估终坑湖的可持续性和健康状况至关重要；回收尾矿库的潜在策略。*****