Microbial communities and methane oxidation processes in Base Mine Lake, a model end-pit lake in the Alberta oilsands

加拿大油砂行业面临的一个挑战是回收受采矿影响的环境，特别是受沥青提取过程中产生的尾矿影响的地区。尾矿中含有多种化学成分（主要是盐类和环烷酸等有机分子），能产生甲烷。目前，尾矿通常储存在被称为尾矿库的露天盆地中。几个采矿作业的长期土地复垦计划包括建设底坑湖（epl）。这些是地表采矿坑中低于品位的水体，最终将成为当地的分水岭。它们应在尾矿材料的长期遏制和补救中发挥作用。虽然epl已经设计并应用于其他采矿作业，但目前在阿尔伯塔油砂中还没有epl。Syncrude正在开发Base Mine Lake （BML）作为他们的EPL试点项目。BML之前是一个活跃的尾矿库，2012年停止接收新鲜尾矿输入，2013年开始接收淡水。BML是EPL概念的试点测试系统，因此增加我们对湖泊中发生的基本过程的理解至关重要。辛克鲁德正在为BML赞助一个多样化的研究项目，以了解这些过程，包括尾矿库关闭和封顶后系统的生物学和生物地球化学如何发展。我们在BML研究计划中的具体研究将在回收的头几年监测一些关键的微生物过程。主要目标是更好地了解BML中的甲烷代谢细菌，以及这些细菌如何影响：i)湖泊中的溶解氧浓度，这是决定水是否适合高等生物居住的关键因素，以及ii)有机和无机成分的生物修复。第二个目标是使用基于dna的方法监测湖泊中的整体微生物群落，以便制定填海进度指标，并为后期EPL开发制定最佳实践。

One challenge facing the oilsands industry in Canada is reclaiming mining-impacted environments, especially areas affected by tailings produced during bitumen extraction. The tailings contain various chemical constituents (mainly salts and organic molecules such as naphthenic acids), and can produce methane. At present tailings are usually stored on open basins known as tailings ponds. The long-term land reclamation plans of several mining operations include the construction of End-Pit Lakes (EPLs). These are below-grade bodies of water in surface mining pits that will eventually become integrated into local watersheds. They should function in long-term containment and remediation of tailings material. Although EPLs have been designed and applied in other mining operations, none presently exist in the Alberta oilsands. Syncrude is developing Base Mine Lake (BML) as their pilot EPL project. BML was previously an active tailings pond which ceased to receive fresh tailings input in 2012 and began to receive fresh water in 2013. BML is a pilot test system for the EPL concept, so increasing our understanding of fundamental processes occurring in the lake is critical. Syncrude is sponsoring a diverse research program for BML in order to understand these processes, including how the biology and biogeochemistry of the system develops after tailing pond closure and water-capping. Our specific study within the BML research program will monitor some key microbial processes during the first few years of reclamation. The primary goal is to develop a better understanding of methane-metabolising bacteria in BML, and how these bacteria affect: i) the dissolved oxygen concentrations in the lake, a key factor determining the habitibility of the water for higher organisms, and ii) bioremediation of organic and inorganic constituents. A secondary goal is to monitor overall microbial communities in the lake using DNA-based methods, in order to develop indicators of the reclamation progress and to develop best practices for later EPL development.