Smythe Kirsten K, Cooke Colin A, Drevnick Paul E, Cornett Robert J, Blais Jules M
Department of Earth & Environmental Sciences, University of Ottawa, Ottawa, Ontario, Canada.
Environment & Parks, Government of Alberta, Edmonton, Alberta, Canada; Department of Earth and Atmospheric Science, University of Alberta Edmonton, Alberta, Canada.
Environ Pollut. 2022 Feb 1;294:118567. doi: 10.1016/j.envpol.2021.118567. Epub 2021 Nov 24.
Most bitumen in the Alberta oil sands (Canada) is extracted by thermal in-situ recovery. Despite the widespread use of in-situ bitumen extraction, little information is available on the release of petroleum hydrocarbons by this method to adjacent land and water. Here we analyzed the composition and abundance of parent and alkylated polycyclic aromatic compounds (PACs) in 11 radiometrically-dated lake sediment cores collected near in-situ operations at Cold Lake Alberta to assess potential petroleum contamination sources to surrounding lakes over the past century. Like open-pit mining areas, alkylated PACs in Cold Lake sediments were elevated compared to unsubstituted parent PACs and increased coeval with the onset of bitumen extraction in the area. Diagnostic ratios and pyrogenic indices showed that PAC sources to these lake sediments were dominantly pyrogenic, likely from historic forest fires, however they shifted to more petrogenic sources coeval with expanding oil sands extraction at Cold Lake. PACs in sediment from regional lakes are weakly correlated to their proximity to in-situ oil wells, once corrected for lake area. These results suggest that in-situ operations, via diesel-fueled vehicular emissions and the combustion of natural gas for steam generation, are a source of PACs to nearby lakes, but PACs did not exceed Canadian sediment quality guidelines for the protection of aquatic life.
加拿大阿尔伯塔省油砂中的大多数沥青是通过热原位开采法提取的。尽管原位沥青开采法被广泛使用，但关于该方法向邻近土地和水体释放石油烃的信息却很少。在此，我们分析了在加拿大阿尔伯塔省冷湖附近原位作业区采集的11个经放射性测年的湖泊沉积物岩芯中母体和烷基化多环芳烃（PACs）的组成和丰度，以评估过去一个世纪周边湖泊潜在的石油污染源。与露天矿区一样，冷湖沉积物中的烷基化PACs相比于未取代的母体PACs有所升高，且随着该地区沥青开采的开始而增加。诊断比率和热解指数表明，这些湖泊沉积物中PACs的来源主要是热解源，可能来自历史上的森林火灾，然而随着冷湖油砂开采的扩大，它们转向了更多的成岩源。在对湖泊面积进行校正后，区域湖泊沉积物中的PACs与其距原位油井的距离之间的相关性较弱。这些结果表明，原位作业通过柴油驱动的车辆排放以及用于产生蒸汽的天然气燃烧，是附近湖泊PACs的一个来源，但PACs并未超过加拿大保护水生生物的沉积物质量准则。
