Centre for Environmental Contaminants Research, CSIRO Land and Water, Lucas Heights, NSW, Australia; School of Earth, Atmosphere and Life Sciences, University of Wollongong, Wollongong, NSW, Australia; University of Technology Sydney, NSW, Australia.
Centre for Environmental Contaminants Research, CSIRO Land and Water, Lucas Heights, NSW, Australia.
Environ Pollut. 2021 Sep 15;285:117212. doi: 10.1016/j.envpol.2021.117212. Epub 2021 Apr 23.
Effluent discharges can potentially result in high concentrations of metals entering aquatic environments for short durations, ranging from a few hours to days. The environmental risks of such exposures are challenging to accurately assess. Risk assessment tools for effluent discharges include comparison of toxicant concentrations with guideline values and the use of direct toxicity assessments, both of which were designed to assess continuous, rather than pulse, contaminant exposures. In this study, a chronic pulse-exposure toxicity test was developed using the tropical euryhaline calanoid copepod Acartia sinjiensis. This copepod has a rapid life cycle and is highly sensitive to metal contaminants, with 50% effect concentrations (chronic EC50) for larval development of 1.7, 8.6 and 0.7 μg L for copper, nickel and zinc, respectively. The toxicities of copper and nickel were assessed as a continuous exposure (78 h) and as pulses (3, 6 and 18 h) initiated at varying life stages, from egg to copepodite, and measured larval development over 78 h. Generally, 24-h old nauplii were more sensitive or of similar sensitivity to copper and nickel pulses than 48-h old nauplii. The 78-h test duration enabled observations of chronic effects following pulse exposures, which frequently occurred in the absence of acute effects. The EC50 values for pulse exposures were higher than those of continuous exposure by up to approximately 16-fold and 15-fold for copper and nickel, respectively. When metal-pulse exposure concentrations were expressed using the time-weighted averaged concentration (TAC), resultant concentration response curves were similar to those in continuous exposures to the same metal, suggesting that thresholds based on continuous exposures were also protective for pulse exposures to these metals. This research improves our understanding of the toxicity of pulse contaminant exposures and assists with developing improved approaches to for the risk assessment and regulation of short-term contaminant discharges.
污水排放可能会导致金属在短时间内（数小时至数天）大量进入水生环境。评估此类暴露的环境风险具有挑战性。污水排放的风险评估工具包括将有毒物质浓度与指南值进行比较，以及使用直接毒性评估，这两种方法都是为了评估连续的、而不是脉冲的污染物暴露而设计的。在这项研究中，使用热带广盐桡足类桡足类生物新月菱形海蚤（Acartia sinjiensis）开发了一种慢性脉冲暴露毒性测试。这种桡足类生物生命周期短，对金属污染物高度敏感，其幼虫发育的 50%效应浓度（慢性 EC50）分别为铜、镍和锌的 1.7、8.6 和 0.7μg/L。铜和镍的毒性被评估为连续暴露（78 小时）和脉冲暴露（3、6 和 18 小时），起始于从卵到桡足幼体的不同生命阶段，并在 78 小时内测量幼虫发育情况。一般来说，24 小时龄的无节幼体对铜和镍脉冲的敏感性或相似，而 48 小时龄的无节幼体则更高。78 小时的测试时间可以观察到脉冲暴露后的慢性效应，而这些慢性效应经常在没有急性效应的情况下发生。脉冲暴露的 EC50 值比连续暴露高约 16 倍和 15 倍，分别为铜和镍。当金属脉冲暴露浓度用时间加权平均浓度（TAC）表示时，产生的浓度-反应曲线与金属连续暴露时的曲线相似，这表明基于连续暴露的阈值也对这些金属的脉冲暴露具有保护作用。这项研究提高了我们对脉冲污染物暴露毒性的理解，并有助于开发改进的方法，用于短期污染物排放的风险评估和监管。
