Meador J P, Ernest D, Hohn A A, Tilbury K, Gorzelany J, Worthy G, Stein J E
Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. East, Seattle, Washington 98112, USA.
Arch Environ Contam Toxicol. 1999 Jan;36(1):87-98. doi: 10.1007/s002449900446.
We analyzed tissue samples from bottlenose dolphins (Tursiops truncatus) that had stranded on beaches in Texas and Florida over a 1-year period starting in September 1991. The concentrations of 10 elements plus methyl mercury (MeHg) were determined in brain, kidney, and liver, and we examined these results for differences based upon age, site, sex, and tissue type. A strong inverse relationship between total mercury (Hg) and the percentage that was MeHg was found in liver, kidney, and brain tissue, presumably due to demethylation of MeHg. A threshold concentration was found for total Hg in brain tissue, indicating that most Hg was present as MeHg up to about 8 years of age. Increases in total Hg after this age were accompanied by an increase in the ratio of total Hg to MeHg, indicating demethylation. Strong relationships were found between total Hg in liver and age and between total Hg and selenium in liver, which have been observed before in many fish- and squid-eating marine mammals. The only difference based on sex of the animals was observed for MeHg, which was higher in females and contrary to the pattern often observed for organic contaminants. Several elements (copper, Hg, lead, zinc) exhibited intersite differences, which were not consistent. Bottlenose dolphin from Florida exhibited the highest levels of MeHg and total Hg, while animals from Texas exhibited the highest levels of lead, copper, and zinc. The essential elements copper and zinc were expected to be the same for the Texas and Florida animals; however, observed differences may indicate population differences in basic physiological levels, dietary intake, or health status.
我们分析了1991年9月开始的为期1年内在得克萨斯州和佛罗里达州海滩搁浅的宽吻海豚（Tursiops truncatus）的组织样本。测定了脑、肾和肝脏中10种元素以及甲基汞（MeHg）的浓度，并根据年龄、地点、性别和组织类型对这些结果进行了差异检验。在肝脏、肾脏和脑组织中发现总汞（Hg）与甲基汞所占百分比之间存在很强的负相关关系，这可能是由于甲基汞的去甲基化作用。在脑组织中发现了总汞的阈值浓度，表明在大约8岁之前，大多数汞以甲基汞的形式存在。这个年龄之后总汞的增加伴随着总汞与甲基汞比例的增加，表明发生了去甲基化。在肝脏中总汞与年龄之间以及总汞与硒之间发现了很强的相关性，这在之前许多以鱼类和鱿鱼为食的海洋哺乳动物中都有观察到。基于动物性别的唯一差异是甲基汞，雌性中的甲基汞含量更高，这与有机污染物通常观察到的模式相反。几种元素（铜、汞、铅、锌）表现出地点间差异，但并不一致。来自佛罗里达州的宽吻海豚甲基汞和总汞含量最高，而来自得克萨斯州的动物铅、铜和锌含量最高。预期得克萨斯州和佛罗里达州的动物体内的必需元素铜和锌含量相同；然而，观察到的差异可能表明在基本生理水平、饮食摄入或健康状况方面存在种群差异。
