In the natural ecosystem, aquatic organisms are exposed to a cocktail of chemicals that may result in toxicological responses differing from those of individual chemicals. In the present study, mussels were exposed using a semi-static and triplicated design to either control (no added metal), 50 µg l (Hg alone), 50 µg l (Cd alone), or 50 µg l Hg plus 50 µg l Cd (Hg + Cd) mixture for 14 days. Tissues were collected on days 0, 2, 4, 8, and 14 for metal analysis and sub-lethal responses using a suite of assays. Tissue metal concentrations were not significantly different in the single metal (Hg or Cd) compared to the Hg plus Cd mixture treatment for all tissues, apart from the gill of the Cd alone treatment. At the end of the experiment, the gill Cd concentration was significantly increased in the Hg plus Cd mixture compared to the Cd alone treatment, suggesting the influence of Hg on Cd uptake. The percentage increases of the Hg plus Cd mixture compared to the arithmetic sum of the individual metals were ( %): 20.2, 9.3, 25.1, 23.8, 10.7, and 12.4 for adductor muscle, digestive gland, gill, gonad, remaining soft tissue, and haemolymph, respectively. There were no observed treatment effects on total haemocyte count, haemolymph protein, or glucose concentration in the cell-free haemolymph. Neither was there any treatment effect on osmotic pressure, ions in the tissues, or in the cell-free haemolymph. At the end of the experiment, Hg-mediated oxidative damage, as an increase of thiobarbituric reactive substances (TBARS) and apparent depletion of total glutathione. This was observed in the gill and digestive gland of the Hg alone and Hg plus Cd mixture. Histopathology examination showed similar pathology in the Hg alone and the Hg plus Cd treatment. In conclusion, despite some oxidative stress and pathology during metal exposure, the accumulation of metals and effects on mussel health were similar between single exposures and a mixture of Hg plus Cd. In terms of risk assessment, regulations for the individual metals should suffice to protect against the mixture of Hg plus Cd, at least for adult in full-strength seawater.

中文翻译：

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金属混合物对贻贝、贻贝的生物累积和亚致死生理效应：持续暴露于汞和镉的二元混合物


在自然生态系统中，水生生物暴露于多种化学物质的混合物中，这些化学物质可能会导致与单个化学物质不同的毒理学反应。在本研究中，使用半静态和三重设计将贻贝暴露于对照（不添加金属）、50 µg l（仅 Hg）、50 µg l（仅 Cd）或 50 µg l Hg 加 50 µg l Cd (Hg + Cd) 混合物 14 天。在第 0、2、4、8 和 14 天收集组织，使用一套测定进行金属分析和亚致死反应。与汞加镉混合物处理相比，除单独镉处理的鳃外，所有组织的组织金属浓度在单一金属（汞或镉）中没有显着差异。实验结束时，与单独处理镉相比，汞加镉混合物中的鳃镉浓度显着增加，表明汞对镉吸收的影响。与单个金属的算术总和相比，汞加镉混合物的增加百分比为 (%)：内收肌、消化腺、鳃、性腺、剩余软组织的 20.2、9.3、25.1、23.8、10.7 和 12.4和血淋巴。没有观察到治疗对总血细胞计数、血淋巴蛋白或无细胞血淋巴中葡萄糖浓度的影响。对组织中的渗透压、离子或无细胞血淋巴也没有任何治疗效果。实验结束时，汞介导的氧化损伤表现为硫代巴比妥反应物质 (TBARS) 的增加和总谷胱甘肽的明显消耗。这是在单独的汞和汞加镉混合物的鳃和消化腺中观察到的。组织病理学检查显示单独汞治疗和汞加镉治疗的病理学相似。 总之，尽管金属暴露期间存在一些氧化应激和病理学，但单次暴露和汞加镉混合物的金属积累和对贻贝健康的影响相似。在风险评估方面，对各种金属的规定应足以防止汞加镉的混合物，至少对于全浓度海水中的成人来说是这样。