Fragoso Nuno M, Hodson Peter V, Zambon Silvia
School of Environmental Studies, Queen's University, Kingston, Ontario, Canada, K7L 3N6.
Environ Monit Assess. 2006 May;116(1-3):481-511. doi: 10.1007/s10661-006-7667-5.
The ecological risks of polynuclear aromatic hydrocarbons (PAH) in aquatic sediments will vary with both toxicity and bioavailability to aquatic biota. While there are standardized protocols to test the acute toxicity of sediment-borne compounds to aquatic invertebrates, there are none for assessing bioavailability to fish. We found that sediment-borne PAH caused an exposure-dependent induction of cytochrome P450 (CYP1A) enzymes in rainbow trout (Oncorhynchus mykiss) fingerlings exposed in semi-static 96 h bioassays, as shown by increased activity of ethoxyresorufin-o-deethylase (EROD). Assuming that PAH are taken up by trout due to partitioning from organic and inorganic constituents of sediments, we tested the effect of different test variables on bioaccumulation using induction as an index of exposure. EROD activity increased with exposure of fish to increasing volumes of sediments containing PAH, i.e., with increasing ratios of sediment to water. Uptake of single compounds from sandy sediments did not differ from uptake from clay or low organic (7% LOI - loss on ignition) sediments, but decreased when organic content was very high (58% LOI). Maximum induction was observed within 24 h of exposure and at 7.5 degrees C relative to 15, 22, or 28 degrees C. Storage and handling techniques had minor effects on sediment EROD induction potency. Absolute EROD activity was greater in white sucker (Catostomus commersoni) a benthic species, than in trout, a pelagic species. However, when basal (negative control) activity was accounted for, there was no difference in response between the species. Together, these experiments provide a basis for developing a standard protocol to test the bioavailability to fish of sediment-borne PAH.
水生沉积物中多环芳烃（PAH）的生态风险会因对水生生物群的毒性和生物可利用性而有所不同。虽然有标准化协议来测试沉积物中化合物对水生无脊椎动物的急性毒性，但却没有用于评估对鱼类生物可利用性的协议。我们发现，在半静态96小时生物测定中暴露的虹鳟（Oncorhynchus mykiss）幼鱼中，沉积物中的PAH会导致细胞色素P450（CYP1A）酶的暴露依赖性诱导，乙氧基异吩唑酮 - O - 脱乙基酶（EROD）活性增加即表明了这一点。假设PAH是由于从沉积物的有机和无机成分中分配而被鳟鱼吸收，我们使用诱导作为暴露指标，测试了不同测试变量对生物累积的影响。EROD活性随着鱼类暴露于含有PAH的沉积物量增加而增加，即随着沉积物与水的比例增加而增加。从沙质沉积物中摄取单一化合物与从粘土或低有机（7% 烧失量 - 烧失量）沉积物中的摄取没有差异，但当有机含量非常高（58% 烧失量）时摄取量会降低。在暴露24小时内以及相对于15、22或28摄氏度的7.5摄氏度时观察到最大诱导。储存和处理技术对沉积物EROD诱导效力的影响较小。底栖物种白亚口鱼（Catostomus commersoni）的绝对EROD活性高于中上层物种鳟鱼。然而，当考虑基础（阴性对照）活性时，物种之间的反应没有差异。总之，这些实验为制定测试沉积物中PAH对鱼类生物可利用性的标准协议提供了基础。
