Microbial community development in Base Mine Lake, the first end-pit-lake in the Alberta oil sands region

加拿大油砂行业面临的一个挑战是恢复受采矿影响的环境。一个特别的问题是在沥青提取过程中产生的液体尾矿废物，其中含有各种令人担忧的化学成分，如环烷酸。几个油砂开采作业的长期填海造地计划包括建造矿坑尾湖。这些是露天采矿坑中低于等级的水体，最终将整合到当地的流域中。它们应该在尾矿的长期遏制和回收方面发挥理想的作用。2012年底，辛克鲁德委托基矿湖(BML)作为油砂地区的第一个全面试点EPL。BML包含一个50米深的尾矿层，上面覆盖着10米的淡水盖子。自2013年以来，该湖的生物、化学和物理特性一直受到密切监测。BML的行为在许多方面类似于自然的、季节性分层的亚北极湖泊。有一个活跃的微生物群落，但高等生物的定居仍然非常有限。积极管理水中的悬浮固体使湖泊随着时间的推移变得更加清澈，导致藻类生长增加。我们研究项目的主要目标是：1)随着时间的推移，监测湖泊中微生物群落的发展。到目前为止，我们注意到高等(真核)生物的物种多样性逐渐增加，这表明随着时间的推移，这个湖正在变得更加自然。2)了解关键微生物在有机污染物生物修复中的作用。了解这些微生物及其生物修复潜力可能有助于制定管理策略，以最大限度地发挥它们的活性。3)了解藻类在湖泊碳循环中的作用。该湖可能正在从以碳氢化合物降解为基础的主要异养系统向以藻类生长为基础的主要光营养系统过渡。这可能会改变氧状态和生物修复潜力等参数。

One challenge facing the oilsands industry in Canada is reclaiming mining-impacted environments. A particular problem is the liquid tailings waste produced during bitumen extraction, which contains various chemical constituents of concern such as naphthenic acids. The long-term land reclamationplans of several oilsands 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 ideally function in long-term containment and reclamation of tailings. At the end of 2012 Syncrude commissioned Base Mine Lake (BML) as the first full-scale pilot EPL in the oilsands region. BML contains a 50-m-deep layer of tailings overlain with a 10-m freshwater cap. The biology, chemistry, and physical properties of the lake have been intensively monitored since 2013. BML behaves in many ways similarly to a natural, seasonally stratified subarctic lake. There is an active microbial community but still a very limited colonization by higher organisms. Active management of suspended solids in the water has caused the lake has become clearer over time, leading to an increase in algal growth. The primary goals of our research project are: 1) To monitor the development of microbial communites in the lake over time. To date we have noted a gradual increase in the species diversity of higher (eukaryotic) organisms, suggesting that the lake is becoming more natural over time. 2) To understand the roles of key microbes in bioremediation of organic pollutants. Understanding these microbes and their bioremediation potentials may inform management strategies to maximize their activities. 3) To understand the increasing role of algae in the carbon cycle of the lake. The lake may be transitioning from a primarily heterotrophic system based on degradation of hydrocarbons to a primarily phototrophic system based on algal growth. This may change parameters such as oxygen status and bioremediation potential.