Svecevicius Gintaras, Kazlauskiene Nijole, Vosyliene Milda Z
Laboratory of Ecology and Physiology of Hydrobionts, Akademijos 2, Institute of Ecology, LT-2600, Vilnius, Lithuania.
Environ Sci Pollut Res Int. 2003;10(5):281-3. doi: 10.1065/espr2003.06.157.
GOAL, SCOPE AND BACKGROUND: Orimulsion (stable emulsion of natural bitumen and water) is a new imported industrial fuel in Lithuania. No data on its toxicity to fish is freely available. The aim of this study was to investigate sensitivity of rainbow trout (Oncorhynchus mykiss) to acute and chronic toxicity of orimulsion and to estimate the Maximum Acceptable Toxicant Concentration (MATC) of orimulsion to fish.
Laboratory tests were conducted on rainbow trout in all stages of development (embryos, larvae, adults). Acute toxicity (96-hour duration) and long-term (28 or 60-day duration) tests evaluating the wide range spectrum of biological indices were performed under semi-static conditions.
Median lethal concentration (96-hour LC50) values and their 95% confidence intervals derived from the tests were: 0.1 (0.09-0.12) to embryos, 0.06 (0.05-0.07) to larvae and 2.22 (2.02-2.43) to adult fish, and 28-day LC50 to adult fish was found to be 0.26 (0.21-0.32) g/l of total orimulsion respectively. The acute toxicity of orimulsion to rainbow trout can be characterised by a narrow zone of toxic effect and a sharp boundary between lethal and sublethal concentrations. The lowest 'safe' or 'no-effect' concentration values of total orimulsion obtained in long-term tests were equal to 0.09 g/l to adult fish, 0.019 g/l to embryos, and 0.0017 g/l to larvae. Proposed value of 'application factor' for orimulsion was found to be equal to 0.03. Since orimulsion has the property to disperse in all water volume, its toxic effect on fish can be characterised by the combined effects of dispersion and water-soluble-fraction.
Maximum Acceptable Toxicant Concentration (MATC) of 0.0017 g/l of total orimulsion to fish was derived from long-term tests based on the most sensitive parameter of rainbow trout larvae (relative mass increase at the end of the test). According to substance toxicity classification accepted for Lithuanian inland waters, orimulsion can be referred to substances of 'moderate' toxicity to fish.
For prediction and evaluation of toxic impact of orimulsion accident spills on fish, some recommendations should be given. Since orimulsion has the property to disperse in all water volume during short time periods, the amounts of both spilled orimulsion and polluted water should be ascertained. Once both parameters are known, the real concentration of orimulsion in the water body must be determined. Then this concentration must be compared with 'safe' concentration to fish. By use of 'application factor' 0.03, approximate MATC for other fish species can be estimated when only acute toxicity data (96-hour LC50 value) is available.
目标、范围及背景：奥里乳化油（天然沥青与水的稳定乳液）是立陶宛一种新进口的工业燃料。目前尚无关于其对鱼类毒性的公开数据。本研究旨在调查虹鳟（Oncorhynchus mykiss）对奥里乳化油急性和慢性毒性的敏感性，并估算奥里乳化油对鱼类的最大可接受毒物浓度（MATC）。
对虹鳟发育的各个阶段（胚胎、幼体、成鱼）进行了实验室测试。在半静态条件下进行了急性毒性试验（96小时）和长期试验（28天或60天），评估了广泛的生物学指标。
试验得出的半数致死浓度（96小时LC50）值及其95%置信区间为：胚胎为0.1（0.09 - 0.12），幼体为0.06（0.05 - 0.07），成鱼为2.22（2.02 - 2.43），成鱼的28天LC50分别为0.26（0.21 - 0.32）g/l总奥里乳化油。奥里乳化油对虹鳟的急性毒性表现为毒性效应范围窄，致死浓度和亚致死浓度之间界限分明。长期试验中获得的总奥里乳化油的最低“安全”或“无效应”浓度值，成鱼为0.09 g/l，胚胎为0.019 g/l，幼体为0.0017 g/l。奥里乳化油的“应用因子”建议值为0.03。由于奥里乳化油具有在整个水体中分散的特性，其对鱼类的毒性作用可通过分散作用和水溶性部分的综合作用来表征。
基于虹鳟幼体最敏感参数（试验结束时相对质量增加）的长期试验得出，总奥里乳化油对鱼类的最大可接受毒物浓度（MATC）为0.0017 g/l。根据立陶宛内陆水域认可的物质毒性分类，奥里乳化油可归为对鱼类“中等”毒性的物质。
为预测和评估奥里乳化油事故泄漏对鱼类的毒性影响，应给出一些建议。由于奥里乳化油具有在短时间内在整个水体中分散的特性，应确定泄漏的奥里乳化油和受污染水的量。一旦知道这两个参数，就必须确定水体中奥里乳化油的实际浓度。然后将该浓度与鱼类的“安全”浓度进行比较。当仅获得急性毒性数据（96小时LC50值）时，通过使用“应用因子”0.03，可以估算其他鱼类的近似MATC。
