The wide range of applications of nanomaterials (NM) in different fields has led to both uncontrolled production and release into environmental compartments, such as aquatic systems, where final disposal occurs. Some efforts have been made to estimate their concentrations in environmental matrices; however, little is known about the actual effects of environmental NM concentrations on biota. The aims of the present review are to (i) expose the state of the art of the most applied NM and their actual concentrations regarding how much is being released to the aquatic environment and which are the predicted ones; (ii) analyze the current literature to elucidate if the aforementioned conditions were proven to cause deleterious effects on the associated organisms; and (iii) identify gaps in the knowledge regarding whether the actual NM concentrations are harmful to aquatic biota. These novel materials are expected to being released into the environment in the range of hundreds to thousands of tons per year, with Si- and Ti-based NM being the two most important. The estimated environmental NM concentrations are in the low range of ng to µg/L, except for Ti-based ones, which concentrations reach values on the order of mg/L. Empirical information regarding the ecotoxicity of environmental NM concentrations mainly focused on metal-based NM, however, it resulted poor and unbalanced in terms of materials and test species. Given its high predicted environmental concentration in comparison with the others, the ecotoxicity of Ti-based NM has been well assessed in algae and fish, while little is known regarding other NM types. While only a few marine species were addressed, the freshwater species and accounted for the majority of studies on invertebrate and fish groups, respectively. Most of the reported responses are related to oxidative stress. Overall, we consider that invertebrate groups are the most vulnerable, with emphasis on microcrustaceans, as environmentally realistic metal-based NM concentration even caused mortality in some species. In the case of fish, we assumed that environmental concentrations of Ti-based NM represent a growing concern and threat; however, further studies should be carried out by employing other kinds of NM. Furthermore, more ecotoxicological information is needed in the case of carbon-based NM, as they are expected to considerably increase in terms of released amounts and applications in the near future.

中文翻译：

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水生环境中的金属基纳米材料：到目前为止，我们对其生态毒性了解多少？


纳米材料（NM）在不同领域的广泛应用导致其生产不受控制，并释放到环境区域，例如最终处置的水生系统。已做出一些努力来估算它们在环境基质中的浓度；然而，人们对环境 NM 浓度对生物群的实际影响知之甚少。本次审查的目的是 (i) 揭示最常用的 NM 的最新技术及其实际浓度，即有多少物质被释放到水生环境中，哪些是预测的； (ii) 分析现有文献，以阐明上述条件是否被证明会对相关生物体造成有害影响； (iii) 确定实际 NM 浓度是否对水生生物群有害的知识差距。这些新型材料预计每年会释放到环境中数百至数千吨，其中硅基和钛基纳米材料是最重要的两种材料。估计的环境 NM 浓度在 ng 至 µg/L 的低范围内，但钛基 NM 浓度除外，其浓度达到 mg/L 量级。关于环境NM浓度生态毒性的经验信息主要集中在金属基NM上，但其材料和测试种类方面的结果较差且不平衡。鉴于与其他 NM 相比，其预测的环境浓度较高，钛基 NM 的生态毒性已在藻类和鱼类中得到了很好的评估，而对于其他 NM 类型则知之甚少。虽然只涉及少数海洋物种，但淡水物种和鱼类分别占无脊椎动物和鱼类研究的大部分。 大多数报道的反应与氧化应激有关。总体而言，我们认为无脊椎动物群体是最脆弱的，尤其是微型甲壳类动物，因为符合环境要求的金属 NM 浓度甚至导致某些物种死亡。就鱼类而言，我们假设钛基 NM 的环境浓度代表了日益增长的担忧和威胁；然而，还应该通过使用其他类型的 NM 来进行进一步的研究。此外，就碳基纳米材料而言，需要更多的生态毒理学信息，因为预计在不久的将来它们的释放量和应用将大幅增加。