Polycyclic aromatic compounds (PACs) threaten the health of aquatic ecosystems. In northeastern Alberta, Canada, decades of oil sands mining and upgrading activities have increased PAC delivery into freshwaters. This PAC pollution adds to natural inputs from river erosion of bitumen-bearing McMurray Formation outcrops and wildfire inputs. Quantifying these petrogenic and pyrogenic PAC inputs, which is key for understanding industrial impacts, remains a challenge. To distinguish petrogenic from pyrogenic inputs, we characterized river water PACs before and after the 2016 Fort McMurray wildfire, one of the largest natural disasters in Canadian history. Samples of wildfire ash and outcropping bitumen allow us to distinguish between these important PAC sources. River PAC concentrations ranged over multiple orders of magnitude (10s–10 000s ng/L). Petrogenic PACs dominated most of the postfire period with only short-term episodes of pyrogenic signatures in burned watersheds due to the wash-in of ash from the watershed. Wildfire PAC inputs during these events resulted in exceptional increases in concentrations that met or exceeded high (petrogenic) background concentrations, driven by the natural erosion of outcropping bitumen. Our dataset offers the first quantification of these two important PAC sources in this industrialized region and provides new insight into the impacts of increasing wildfire frequency and severity across the Boreal Forest.

中文翻译：

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北方特大火灾后以岩源为主的河流中的多环芳烃化合物

多环芳香族化合物 (PAC) 威胁着水生生态系统的健康。在加拿大艾伯塔省东北部，数十年的油砂开采和升级活动增加了 PAC 向淡水的输送。这种 PAC 污染增加了来自含沥青的 McMurray 地层露头的河流侵蚀和野火输入的自然输入。量化这些成岩和热原 PAC 输入，这是理解工业影响的关键，仍然是一个挑战。为了区分岩源和热源输入，我们在 2016 年麦克默里堡野火（加拿大历史上最大的自然灾害之一）前后对河水 PAC 进行了表征。野火灰和露头沥青样本使我们能够区分这些重要的 PAC 来源。河流 PAC 浓度范围超过多个数量级 (10s–10 000s ng/L)。成因 PAC 在火灾后的大部分时间里占主导地位，由于流域灰烬的冲刷，在燃烧的流域中只有短期的热源特征。在这些事件期间，野火 PAC 输入导致浓度异常增加，达到或超过高（成岩）背景浓度，这是由露头沥青的自然侵蚀驱动的。我们的数据集首次量化了这个工业化地区这两个重要的 PAC 来源，并为整个北方森林野火频率和严重程度增加的影响提供了新的见解。在这些事件期间，野火 PAC 输入导致浓度异常增加，达到或超过高（成岩）背景浓度，这是由露头沥青的自然侵蚀驱动的。我们的数据集首次量化了这个工业化地区这两个重要的 PAC 来源，并为整个北方森林野火频率和严重程度增加的影响提供了新的见解。在这些事件期间，野火 PAC 输入导致浓度异常增加，达到或超过高（成岩）背景浓度，这是由露头沥青的自然侵蚀驱动的。我们的数据集首次量化了这个工业化地区这两个重要的 PAC 来源，并为整个北方森林野火频率和严重程度增加的影响提供了新的见解。