Environment and Parks, Government of Alberta, Edmonton, Alberta T5J 5C6, Canada.
Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada.
Environ Sci Technol. 2022 Jul 5;56(13):9408-9416. doi: 10.1021/acs.est.2c01671. Epub 2022 Jun 16.
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.
多环芳烃（PACs）威胁着水生生态系统的健康。在加拿大阿尔伯塔省东北部，几十年的油砂开采和升级活动增加了 PAC 进入淡水的输送。这种 PAC 污染加剧了源自沥青bearing McMurray 组露头的河流侵蚀和野火的自然输入。量化这些源自石油和源自燃烧的 PAC 输入，这对于理解工业影响至关重要，但仍然是一个挑战。为了区分源自石油和源自燃烧的输入，我们在 2016 年麦克默里堡野火前后对河水 PACs 进行了特征描述，这是加拿大历史上最大的自然灾害之一。野火灰和露头沥青的样本使我们能够区分这些重要的 PAC 来源。河水中 PAC 的浓度范围跨越多个数量级（10s-10000s ng/L）。在火灾后的大部分时间里，源自石油的 PACs 占主导地位，只有在燃烧流域中由于流域内的灰分冲洗而出现短时间的源自燃烧的特征。在这些事件中，野火 PAC 输入导致浓度异常增加，达到或超过了高（源自石油）背景浓度，这是由露头沥青的自然侵蚀驱动的。我们的数据集首次对这个工业化地区的这两个重要 PAC 来源进行了量化，并为日益增加的野火频率和严重程度对北方森林的影响提供了新的见解。
