Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada.
Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C8, Canada.
Environ Sci Technol. 2021 Feb 2;55(3):1721-1729. doi: 10.1021/acs.est.0c06349. Epub 2021 Jan 15.
Due to high viscosity, bitumen extracted from the Alberta oil sands is diluted with natural gas condensates to form diluted bitumen (dilbit) to facilitate transport through pipelines. Dilbit that is spilled into or near a waterbody is subject to environmental weathering processes such as evaporation and interaction with sediments. This is the first study that assessed the toxicity of weathered sediment-bound dilbit (WSD) to fish early life stages. Exposure of zebrafish () embryos to water-soluble fractions (WSFs) or water-accommodated fractions (WAFs) of WSD from 30 min to 120 h postfertilization resulted in pericardial edema, yolk sac edema, and incidences of uninflated swim bladder. The presence of oil-mineral aggregates (OMAs) in the WAFs greatly increased toxicity, despite all fractions having similar concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs). There were greater mRNA abundances in larvae exposed to WAFs, suggesting that there were differences in bioavailability of PAHs between fractions. However, there was little evidence that embryotoxicity was caused by oxidative stress. Results suggest that evaporation and sediment interaction do not completely attenuate toxicity of dilbit to zebrafish early life stages, and OMAs in exposures exacerbate toxicity.
由于高粘度，从阿尔伯塔油砂中提取的沥青与天然气凝析油混合形成稀释沥青（dilbit），以方便通过管道运输。如果稀释沥青泄漏到水体中或附近，就会受到环境风化过程的影响，如蒸发和与沉积物的相互作用。这是第一项评估风化沉积物结合稀释沥青（WSD）对鱼类早期生活阶段毒性的研究。从受精后 30 分钟到 120 小时，斑马鱼（）胚胎暴露于 WSD 的水溶性部分（WSF）或水可容纳部分（WAF）中，导致心包水肿、卵黄囊水肿和未充气鳔发生率增加。尽管所有部分都具有相似浓度的溶解多环芳烃（PAHs），但 WAF 中的油矿物聚集体（OMA）大大增加了毒性。暴露于 WAF 的幼虫中存在更高的 mRNA 丰度，这表明各部分之间 PAHs 的生物利用度存在差异。然而，几乎没有证据表明胚胎毒性是由氧化应激引起的。结果表明，蒸发和沉积物相互作用并不能完全减轻稀释沥青对斑马鱼早期生活阶段的毒性，暴露于 OMA 会加剧毒性。
