Toxicity Changes of Heavily Polluted River Sediments on Daphnia magna Before and After Dredging
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Toxicity Changes of Heavily Polluted River Sediments on Daphnia magna Before and After Dredging Li‑Ling Zhang1,2 · Zhou‑Tao Pei1,2 · Ya‑Ni Zhao3 · Jing Zhang1,2 · Rou‑Rou Xu1,2 · Meng Zhang1,2 · Wen‑Qiang Wang1,2 · Li‑Wei Sun1,2 · Guang‑Can Zhu1,2 Received: 18 May 2020 / Accepted: 27 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Most of the pollutants discharged into the water will deposit at the bottom of the river and may cause biological toxicity. Daphnia magna-elutriate toxicity bioassay was usually applied to evaluate sediment toxicity. However, the loss of hydrophobic pollutants during the elutriating will lead to the underestimation of sediment toxicity. The purpose of this study is to apply the optimized immobilized sediments to D. magna test, so it can be directly exposed to the sediments and get accurate sediment toxicity results. The optimized immobilized sediment was prepared by mixing 1 g sediment with 7.5 mL 3% (w/v) alginate and hardened in a 4% (w/v) CaCl2 solution. Based on D. magna acute toxicity test, the median lethal concentration values (LC50) of the spiked Cu and diuron measured by using immobilized sediment were both lower than that of using the elutriate, in which the difference of Cu-LC50 reached a significant level. The toxicity changes of sediment in the polluted rivers before and after dredging were then be evaluated by using the immobilized sediment. The toxicity of the sediments at four sites decreased from acute-toxic (pro-dredging) to slight-acute-toxic and nontoxic (post-dredging). Keywords Immobilized sediment · Daphnia magna · Acute toxicity · Whole sediment toxicity Sediment is an essential part of the water body and plays a significant role in the material cycle (Burton Jr and Scott 1992). With the sewage was discharged into the river, the un-decomposed pollutants will be adsorbed on the solid particles and settled on the bottom. The long-time accumulation Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00128-020-03037-y) contains supplementary material, which is available to authorized users.
will make the concentration of pollutants in the sediments several orders of magnitude higher than these in the overlying water, which may lead to a critical environmental issue (de Andrade et al. 2019). At present, the sediment quality evaluations are mainly focused on specific chemical analysis results; however, the results cannot reflect the impact of sediment on aquatic organisms.
* Li‑Wei Sun liwei‑[email protected]
Meng Zhang [email protected]
* Guang‑Can Zhu gc‑[email protected]
Wen‑Qiang Wang [email protected]
Li‑Ling Zhang [email protected]
1
Zhou‑Tao Pei [email protected]
School of Energy & Environment, Southeast University, Nanjing 210096, Jiangsu, China
2
Ya‑Ni Zhao [email protected]
Taihu Lake Water Environment Engineering Research Center (Wuxi), Southeast University, Wuxi 214061, Jiangsu, China
3
Water Pollution Control and Ecological Resto
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