Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada.
Department of Biological Sciences and Water Institute for Sustainable Environments (WISE), University of Lethbridge, Lethbridge, AB, T1K 3M4, Canada.
Chemosphere. 2020 Jun;249:126073. doi: 10.1016/j.chemosphere.2020.126073. Epub 2020 Feb 1.
Oil sands process-affected water (OSPW) is a byproduct of bitumen extraction in the surface-mining oil sands industry in Alberta, Canada. Organic compounds in OSPW can be acutely or chronically toxic to aquatic organisms, so part of a long-term strategy for remediation of OSPW is ageing of water in artificial lakes, termed end-pit lakes. BaseMine Lake (BML) is the first oil sands end-pit lake, commissioned in 2012. At the time of its establishment, an effects-directed analysis of BML-OSPW showed that naphthenic acids and polar organic chemical species containing sulfur or nitrogen contributed to its acute lethality. However, the chronic toxicity of these same chemical fractions has not yet been investigated. In this work, the short-term fathead minnow reproductive bioassay was used to assess endocrine-system effects of two fractions of BML-OSPW collected in 2015. One of the fractions (F1) contained predominantly naphthenic acids, while the other (F2) contained non-acidic polar organic chemical species. Exposure of minnows to F1 or F2 at concentrations equivalent to 25% (v/v) of the 2015 BML-OSPW sample (5-15% of the 2012 BML-OSPW sample) did not alter reproductive performance, fertilization success, or concentrations of sex steroids in female or male minnows. Additionally, there were no significant differences in fertility, hatching success, or incidence of morphological indices of embryos collected on day 7 or 14 from exposed breeding trios. However, exposure of male fathead minnow to 25% (v/v) intact 2015 BML-OSPW resulted in a significantly greater hepatosomatic index. Exposure of fathead minnow to refined fractions of dissolved organic chemicals in 2015 BML-OSPW, or a 25% (v/v) of the intact mixture did not affect fertility or fecundity as measured by use of the 21-day reproductive bioassay. These data will be useful in setting future threshold criteria for OSPW reclamation and treatment.
油砂加工影响水（OSPW）是加拿大艾伯塔省地表采矿油砂工业中提取沥青的副产品。OSPW 中的有机化合物可能对水生生物具有急性或慢性毒性，因此，OSPW 长期修复策略的一部分是在人工湖中老化水，称为最终坑湖。BaseMine 湖（BML）是第一个油砂最终坑湖，于 2012 年投入使用。在其建立时，对 BML-OSPW 的定向效应分析表明，环烷酸和含有硫或氮的极性有机化学物质导致其急性致死性。然而，这些相同化学物质的慢性毒性尚未得到研究。在这项工作中，使用短期黑头呆鱼生殖生物测定来评估 2015 年采集的 BML-OSPW 的两个馏分的内分泌系统效应。一个馏分（F1）主要含有环烷酸，而另一个馏分（F2）含有非酸性极性有机化学物质。将小鱼暴露于 F1 或 F2 中，浓度相当于 2015 年 BML-OSPW 样品的 25%（v/v）（相当于 2012 年 BML-OSPW 样品的 5-15%），不会改变繁殖性能、受精成功率或雌性或雄性小鱼中性激素的浓度。此外，从暴露的繁殖三对鱼中收集的第 7 天或第 14 天的胚胎的生育力、孵化成功率或形态学指数没有显著差异。然而，暴露于 25%（v/v）完整的 2015 年 BML-OSPW 的雄性黑头呆鱼的肝体比显著增加。暴露于 2015 年 BML-OSPW 中溶解有机化学品的精制馏分或 25%（v/v）的完整混合物，不会影响使用 21 天生殖生物测定测量的生育力或繁殖力。这些数据将有助于为 OSPW 再利用和处理制定未来的阈值标准。
