Uranium pollution in aquatic ecosystems poses a threat to organisms. However, the metabolism and toxicity of uranium along aquatic food chains remain unknown. Here, we established an artificial aquatic ecosystem to investigate the fate of uranium along the food chain and reveal its potential toxicity. The results displayed a dose– and time–dependent toxicity of uranium on algae, leading to cell deformation and impeding cell proliferation. When uranium-exposed algae are ingested by fish, uranium tends to concentrate in the intestinal system and bones of fish. Comparatively, direct water uranium exposure resulted in a remarkable uranium accumulation in the head, skin, and muscles of fish, suggesting different toxicity depending on distinct exposure pathways. High–level uranium pollution (20 mg L) intensifies the toxicity to fish through food intake compared to direct water exposure. It has also revealed that approximately 25 % and 20 % of U(VI) were reduced to lower valence forms during its accumulation in algae and fish, respectively, and over 10 % of U(IV, VI) converted to U(0) ultimately, through which uranium toxicity was mitigated due to the lower solubility and bioavailability. Overall, this study provides new insights into the fate of uranium during its delivery along the aquatic food chain and highlights the risks associated with consuming uranium–contaminated aquatic products.

中文翻译：

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铀沿水生食物链的转移和转化：对铀对环境风险的新见解


水生生态系统中的铀污染对生物体构成威胁。然而，铀在水生食物链中的代谢和毒性仍然未知。在这里，我们建立了一个人工水生生态系统，以研究铀在食物链中的命运并揭示其潜在毒性。结果显示，铀对藻类具有剂量和时间依赖性毒性，导致细胞变形并阻碍细胞增殖。当鱼摄入暴露于铀的藻类时，铀往往会集中在鱼的肠道系统和骨骼中。相比之下，直接水中铀暴露会导致鱼的头部、皮肤和肌肉中显着的铀积累，这表明不同的暴露途径具有不同的毒性。与直接接触水相比，高浓度铀污染（20 mg/L）通过食物摄入加剧了鱼类的毒性。研究还表明，大约 25% 和 20% 的 U(VI) 在藻类和鱼类中积累期间分别被还原为较低价态，超过 10% 的 U(IV, VI) 最终转化为 U(0) ，由于溶解度和生物利用度较低，铀的毒性得以减轻。总体而言，这项研究为铀在水产食物链中的运输过程提供了新的见解，并强调了与食用受铀污染的水产品相关的风险。