The potential for delayed mortality following short-term episodic pollution events was evaluated by exposing cladocerans (Ceriodaphnia dubia) and rainbow trout (Oncorhynchus mykiss) to zinc (Zn) in various 1- to 48-h and 1- to 96-h exposures, respectively, followed by transferring the exposed organisms to clean water for up to 47 h for C. dubia and up to 95 h for trout for additional observation. For C. dubia, 1-h exposures of up to 3790 µg Zn/L never resulted in mortality during the actual Zn exposures, but by 48 h, a 1-h exposure to 114 µg/L, a concentration similar to the present US national water quality acute criterion for the test water conditions, ultimately killed 70% of C. dubia. With C. dubia, the speed of action of Zn toxicity was faster for intermediate concentrations than for the highest concentrations tested. For rainbow trout, pronounced delayed mortalities by 96 h only occurred following ≥8-h exposures. For both species, ultimate mortalities from Zn exposures ≤8 h mostly presented as delayed mortalities, whereas for exposures ≥24 h, almost all ultimate mortalities presented during the actual exposure periods. With Zn, risks of delayed mortality following exposures to all concentrations tested were much greater for the more sensitive, small-bodied invertebrate (C. dubia) than for the less sensitive, larger-bodied fish (rainbow trout). These results, along with previous studies, show that delayed mortality is an important consideration in evaluating risks to aquatic organisms from brief, episodic exposures to some substances. Environ Toxicol Chem 2021;40:2484–2498. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

中文翻译：

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Ceriodaphnia dubia 和虹鳟鱼在随时间变化的急性锌暴露后的直接和延迟死亡

通过将枝角类动物 ( Ceriodaphnia dubia ) 和虹鳟鱼 ( Oncorhynchus mykiss ) 在 1 至 48 小时和 1 至 96 小时的不同暴露时间中暴露于锌 (Zn) 中，评估了短期偶发性污染事件后延迟死亡的可能性，分别，然后将暴露的生物转移到干净的水中，对于C. dubia长达 47 小时，对于鳟鱼长达 95 小时以进行额外观察。对于C. dubia而言，在实际 Zn 暴露期间，1 小时高达 3790 µg Zn/L 的暴露从未导致死亡，但到 48 小时，1 小时暴露于 114 µg/L 的浓度与目前美国相似国家水质标准为测试水质条件，最终杀死了70%的C. dubia。和C. dubia，锌毒性的作用速度在中等浓度下比测试的最高浓度更快。对于虹鳟鱼，96 小时的明显延迟死亡率仅发生在 ≥8 小时的暴露后。对于这两个物种，锌暴露≤8 小时的最终死亡率大多表现为延迟死亡率，而暴露≥24 小时的最终死亡率几乎都出现在实际暴露期间。对于更敏感、体型较小的无脊椎动物（C. dubia) 比不那么敏感、体型较大的鱼（虹鳟鱼）。这些结果以及之前的研究表明，延迟死亡是评估水生生物因短暂、偶发性接触某些物质而面临的风险时的一个重要考虑因素。环境毒物化学2021；40:2484–2498。© 2021 作者。Wiley Periodicals LLC 代表 SETAC 出版的Environmental Toxicology and Chemistry 。本文由美国政府雇员贡献，他们的工作在美国属于公共领域。