Lethal and sublethal effects of diluted bitumen and conventional oil on fathead minnow (Pimephales promelas) larvae exposed during their early development
Lethal and sublethal effects of diluted bitumen and conventional oil on fathead minnow (Pimephales promelas) larvae exposed during their early development
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DOI：
10.1016/j.aquatox.2021.105884
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发表时间：
2021-06-14
影响因子：
4.5
通讯作者：
Couture, Patrice
中科院分区：
文献类型：
--
作者：
Berube, Roxanne;Gauthier, Charles;Couture, Patrice
加拿大油砂地区越来越多地开采沥青，从而产生了运输需求。当前和预计管道的泄漏会带来重大的环境风险，特别是对于淡水生态系统。稀释沥青（dilbit）对淡水鱼的毒性目前尚不清楚。本研究评估了两种呆鱼（Clearwater McMurray 和 Bluesky）的毒性，并将其与传统油（Lloydminster Heavy）对黑头呆鱼（Pimephales promelas）幼虫的毒性进行了比较。幼虫在孵化后 7 天内暴露于不同浓度的油的水容纳部分 (WAF)。在WAF处理中，测量了挥发性有机化合物（VOC）的浓度，包括苯、甲苯、乙苯、二甲苯（BTEX）、含有6至10个碳原子的烃（C6-10）、多环芳烃（PAH）及其烷基化形式。两种柴油都含有较高浓度的轻质组分，而常规油含有最高浓度的多环芳烃和烷基化多环芳烃。 Clearwater McMurray 迪尔比特导致较高的死亡率，最高可达 65.3%，而其他油类导致劳埃德明斯特油和 Bluesky 的死亡率相似，分别高达 16.5% 和 18.6%。随着总碳氢化合物浓度的增加，所有三种油均诱导 I 相解毒酶 (cyp1a) 基因表达增加。所有三种暴露均诱导谷胱甘肽 S-转移酶 (GST) 活性类似的增加，但 GST 基因表达没有变化。对于 Bluesky 和 Lloydminster 暴露，还观察到丙二醛浓度增加，表明 GST 和 II 相酶对 PAH 代谢物进行生物转化的限速能力。总体而言，这项研究为北美淡水鱼生命早期阶段的迪尔比特与传统油的毒性提供了新的见解，并证明迪尔比特可能比传统油更具毒性，具体取决于其成分和稀释剂比例。
The increasing extraction of bitumen from the oil sands region in Canada is creating a need for transport. Spills from current and projected pipelines represent a significant environmental risk, especially for freshwater ecosystems. The toxicity of diluted bitumen (dilbit) on freshwater fish is largely unknown. This study assessed the toxicity of two dilbits (Clearwater McMurray and Bluesky) and compared their toxicity to a conventional oil (Lloydminster Heavy) on fathead minnow (Pimephales promelas) larvae. Larvae were exposed to various concentrations of the water-accommodated fraction (WAF) of the oils during 7 days from hatching. In the WAF treatments, the concentrations of volatile organic compounds (VOCs), including benzene, toluene, ethylbenzene, xylene (BTEX), hydrocarbons containing 6 to 10 carbon atoms (C6-10), and polycyclic aromatic hydrocarbons (PAHs) and their alkylated forms were measured. Both dilbits contained higher concentrations of light components, while the conventional oil contained the highest concentrations of PAHs and alkylated PAHs. The Clearwater McMurray dilbit induced a higher mortality, with a maximum of 65.3%, while the other oils induced a similar mortality up to 16.5% and 18.6% for Lloydminster and for Bluesky, respectively. All three oils induced an increase in gene expression of the phase I detoxification enzyme (cyp1a) with increasing total hydrocarbon concentrations. All three exposures induced a similar increase in glutathione S-transferase (GST) activity, but no change in gst gene expression. For the Bluesky and Lloydminster exposures, an increase in malondialdehyde concentration was also observed, suggesting a rate limiting capacity of GST and phase II enzymes to perform the biotransformation of the PAH metabolites. Overall, this study brings new insights on the toxicity of dilbits in comparison to conventional oils on early life stages of North American freshwater fish and demonstrated that dilbits can be more toxic than conventional oils, depending on their composition and diluent proportions.