Nero V, Farwell A, Lee L E J, Van Meer T, MacKinnon M D, Dixon D G
Department of Biology, University of Waterloo, Waterloo, Ont., Canada N2L 3G1.
Ecotoxicol Environ Saf. 2006 Oct;65(2):252-64. doi: 10.1016/j.ecoenv.2005.07.009. Epub 2005 Aug 29.
Naphthenic acids (NAs) are naturally occurring saturated linear and cyclic carboxylic acids found in petroleum, including the bitumen contained in the Athabasca Oil Sands deposit in Alberta, Canada. The processing of these oil sands leads to elevated concentrations of NAs, as well as increased salinity from produced waters as a result of ions leaching from the ores, the process aids, and the water associated with the deeper aquifers. These changes can result in waters that challenge reclamation of impacted waters associated with oil sands development. Laboratory tests examined the effects of salinity on NA toxicity using local young-of-the-year yellow perch exposed to a commercially available mixture of NAs (CNA) and an NA mixture that was extracted from oil sands process-affected water (ENA), with and without the addition of sodium sulfate (Na(2)SO(4)). Gill and liver histopathological changes were evaluated in the surviving fish after 3 weeks of exposure. At 6.8 mg/L ENA and 3.6 mg/L CNA, 100% mortality was observed, both with and without the addition of salt. Exposure of yellow perch to 25% of the NA required to give an LC100 (0.9 mg/L CNA; 1. 7 mg/L ENA) resulted in high levels of gill proliferative (epithelial, mucous, and chloride cell) changes, a response that was increased with the addition of 1g/L salt (Na2SO4) for the ENA. The significance of these changes was a reduced gill surface area, which likely caused a reduction in both the transport of NAs within the fish and the exchange of vital respiratory gases. While the gills were affected, no liver alterations were identified following NA or NA+salt exposures. Differences in the chemical composition of the NAs tested may explain the differences in the lethality and histopathology of yellow perch.
环烷酸（NAs）是天然存在的饱和直链和环状羧酸，存在于石油中，包括加拿大艾伯塔省阿萨巴斯卡油砂矿床中的沥青。这些油砂的加工导致环烷酸浓度升高，同时由于矿石、加工助剂以及与深层含水层相关的水中离子的浸出，采出水中的盐度也增加。这些变化会导致与油砂开发相关的受影响水体的复垦面临挑战。实验室测试使用当地当年幼体黄鲈，研究了盐度对环烷酸毒性的影响，这些黄鲈暴露于市售的环烷酸混合物（CNA）以及从受油砂加工影响的水中提取的环烷酸混合物（ENA）中，且分别添加和不添加硫酸钠（Na₂SO₄）。在暴露3周后，对存活的鱼的鳃和肝脏组织病理学变化进行了评估。在6.8 mg/L的ENA和3.6 mg/L的CNA浓度下，无论是否添加盐，均观察到100%的死亡率。将黄鲈暴露于产生LC100所需环烷酸浓度的25%（0.9 mg/L CNA；1.7 mg/L ENA）下，会导致鳃出现高水平的增殖性（上皮、黏液和氯细胞）变化，对于ENA，添加1g/L盐（Na₂SO₄）后这种反应会增强。这些变化的重要性在于鳃表面积减小，这可能导致鱼体内环烷酸的运输以及重要呼吸气体的交换减少。虽然鳃受到了影响，但在环烷酸或环烷酸+盐暴露后未发现肝脏有改变。所测试的环烷酸化学成分的差异可能解释了黄鲈致死率和组织病理学的差异。
