School of the Environment, Trent University, Peterborough, Ontario, Canada K9J 7B8.
Air Quality Research Division, Environment and Climate Change Canada, Toronto, Ontario, Canada M3H 5T4.
Environ Sci Technol. 2021 May 18;55(10):6791-6803. doi: 10.1021/acs.est.1c00507. Epub 2021 Apr 29.
The Athabasca oil sands region (AOSR) in north-eastern Alberta, Canada, contains the world's third largest known bitumen deposit. Oil sands (OS) operations produce emissions known to contribute to acidic and alkaline deposition, which can alter the chemistry of the receiving surface waters, including dissolved organic carbon (DOC). Little is known regarding the natural variability of aquatic DOC among lakes within the AOSR. Surface-water data from 50 lakes were analyzed; variables known to be associated with the light-absorptive properties of DOC (true color [TC]) were evaluated to investigate the potential variability of chromophoric DOC (CDOC). Comparison of TC and DOC revealed two distinct "high" (H) and "low" (L) lake subpopulations, the former being characterized by high relative TC and low DOC, and the latter by the inverse. The H lakes were defined by variables known to be associated with CDOC, while L lakes appeared well-buffered potentially owing to groundwater inputs. The divergent optical properties between subpopulations appeared partially attributable to pH-limited Fe complexation. Trajectory analysis indicated that H lakes most likely to receive atmospheric deposition from OS sources experienced significantly lower pH. These results are contrary to previous studies that found OS emissions to have minimal acidifying effect over lakes throughout the AOSR.
加拿大阿尔伯塔省东北部的阿萨巴斯卡油砂区（AOSR）拥有世界上第三大已知的沥青矿床。油砂作业产生的排放物已知会导致酸性和碱性沉降，从而改变受纳地表水体的化学性质，包括溶解有机碳（DOC）。关于 AOSR 内湖泊水中水生 DOC 的自然变异性知之甚少。分析了来自 50 个湖泊的地表水数据；评估了已知与 DOC 的光吸收特性相关的变量（真色[TC]），以调查发色溶解有机碳（CDOC）的潜在变异性。TC 和 DOC 的比较揭示了两个截然不同的“高”（H）和“低”（L）湖泊亚群，前者的特点是相对 TC 高而 DOC 低，后者则相反。H 湖泊由与 CDOC 相关的变量定义，而 L 湖泊由于地下水输入似乎具有良好的缓冲能力。亚群之间的不同光学特性似乎部分归因于 pH 限制的 Fe 络合。轨迹分析表明，最有可能从 OS 源接收大气沉降的 H 湖泊的 pH 值显著降低。这些结果与先前的研究结果相反，先前的研究表明，OS 排放对 AOSR 整个地区的湖泊几乎没有酸化作用。
