Karic Hanna, Colvin Marienne A, Rosen Gunther, Hoang Tham C
School of Environmental Sustainability, Loyola University Chicago, Chicago, Illinois, USA.
Naval Information Warfare Center Pacific, US Navy, San Diego, California, USA.
Environ Toxicol Chem. 2022 Oct;41(10):2488-2499. doi: 10.1002/etc.5443. Epub 2022 Sep 14.
Freshwater organisms are often exposed to contaminants such as heavy metals from stormwater discharges, which are dependent on rainfall duration and intensity. Therefore, standardized (48- or 96-h) continuous exposure methods developed for whole effluent toxicity (WET) testing might not always accurately convey the effects of stormwater and runoff contaminants. The present study characterized the acute toxicity of copper (Cu), zinc (Zn), and cadmium (Cd) to freshwater amphipods (Hyalella azteca) and cadmium (Cd) to water fleas (Ceriodaphnia dubia) using a modified exposure design that integrated relevant pulsed durations and included post-exposure monitoring. Less than 24-h-old C. dubia and 7 to 8-day-old H. azteca were exposed to water spiked with Cu, Zn, or Cd using 6-, 12-, 26-, or 96-h durations under standard laboratory conditions and monitored for cumulative mortality and reproduction (C. dubia only). Lethal effect (LC10s, LC25s, LC50s) and reproductive effect (EC25s, EC50s) were determined based on either mortality or reproduction of organisms at the end of each pulse (6, 12, or 26 h) and at the end of their respective tests (96 h). For all metals exposed to each organism, acute toxicity was found to be highest for the (96 h) continuous exposures. For pulsed exposures, mortality continued to increase following transfer to clean water for post-exposure monitoring. These results indicate a latent effect of Cu, Zn, and Cd to H. azteca and Cd to C. dubia. The present study concluded that using the continuous (48- or 96-h) WET exposure method overestimates the effects of stormwater and runoff contaminants. However, pulsed exposures without post-exposure monitoring also underestimate the toxicity of contaminants. The proposed pulsed exposure design provides a compromise that is more realistic than current WET methods to assess impacts from episodic events and accounts for potential latent effects that may be overlooked without monitoring post-exposure. Environ Toxicol Chem 2022;41:2488-2499. © 2022 SETAC.
淡水生物常常会接触到诸如来自雨水排放的重金属等污染物，这些污染物取决于降雨持续时间和强度。因此，为全废水毒性（WET）测试开发的标准化（48或96小时）连续暴露方法可能并不总能准确传达雨水和径流污染物的影响。本研究使用一种改良的暴露设计来表征铜（Cu）、锌（Zn）和镉（Cd）对淡水双足类动物（阿氏透明摇蚊）的急性毒性以及镉（Cd）对水蚤（模糊角突蚤）的急性毒性，该设计整合了相关的脉冲持续时间并包括暴露后监测。将小于24小时龄的模糊角突蚤和7至8日龄的阿氏透明摇蚊在标准实验室条件下暴露于添加了Cu、Zn或Cd的水中，暴露持续时间为6、12、26或96小时，并监测累积死亡率和繁殖情况（仅针对模糊角突蚤）。根据每个脉冲（6、12或26小时）结束时以及各自测试（96小时）结束时生物体的死亡率或繁殖情况确定致死效应（LC10、LC25、LC50）和繁殖效应（EC25、EC50）。对于暴露于每种生物体的所有金属，发现（96小时）连续暴露的急性毒性最高。对于脉冲暴露，在转移到清洁水中进行暴露后监测时死亡率持续增加。这些结果表明Cu、Zn和Cd对阿氏透明摇蚊以及Cd对模糊角突蚤具有潜在影响。本研究得出结论，使用连续（48或96小时）WET暴露方法高估了雨水和径流污染物的影响。然而，没有暴露后监测的脉冲暴露也低估了污染物的毒性。所提出的脉冲暴露设计提供了一种折衷方案，比当前的WET方法更现实地评估偶发事件的影响，并考虑到如果没有暴露后监测可能会被忽视的潜在潜在影响。《环境毒理学与化学》2022年；41：2488 - 2499。© 2022 SETAC。
