Abstract Silver nanoparticles (AgNPs) are known to enter the aquatic environment via leachates from landfills or by the effluent or sludge of sewage treatment plants. Even if the AgNPs are sulfidized, Ag from these particles was shown to still be available to several species like the benthic freshwater amphipod Hyalella azteca. However, it is still unknown if the primary uptake of Ag from these particles occurs mainly by Ag ions, or if the main uptake of Ag is by ingestion of AgNPs and if they can be found in the animal tissues or just in the gut content without any tissue transfer. To elucidate the main uptake pathway and localization of AgNPs potentially taken up by H. azteca, we exposed the amphipods to Ag using AgNP containing sewage sludge or dissolved Ag from AgNO3. Further, we seperated the exposed animals into two groups. One had direct contact to the AgNPs enriched sludge, allowing them to feed on it, the second group seperated from the sludge by a strainer allowing only indirect contact by potentially released AgNPs or ions. The animals exposed for 7 days were examined for their total and nano particulate Ag content using (single-particle) inductively coupled plasma mass spectrometry as well as using methods of correlative microscopy. Thus we were able to show, that low amounts of AgNPs were present exclusively in animals with direct contact to the AgNP enriched sludge and only in the region of the gut. No transfer of AgNPs from the gut into the animals tissue was observed by correlative microscopy. However, measurable Ag body burdens in animals from all treatments and groups indicated that ionic uptake is the main uptake pathway for (bio)accumulation of Ag from AgNPs.

中文翻译：

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使用相关显微镜揭示淡水片足类动物 Hyalella azteca 中人造银纳米粒子的吸收途径和银的积累

摘要 银纳米粒子 (AgNPs) 已知通过垃圾填埋场的渗滤液或污水处理厂的流出物或污泥进入水生环境。即使 AgNPs 被硫化，这些颗粒中的 Ag 仍可用于几种物种，如底栖淡水片脚类动物 Hyalella azteca。然而，尚不清楚这些颗粒中 Ag 的主要吸收是否主要通过 Ag 离子发生，或者 Ag 的主要吸收是否通过摄入 AgNPs 以及它们是否可以在动物组织中或仅在肠道内容物中找到而没有任何组织转移。为了阐明可能被 H. azteca 吸收的 AgNPs 的主要吸收途径和定位，我们使用含有下水道污泥的 AgNP 或从 AgNO3 中溶解的 Ag 将片脚类动物暴露于 Ag。此外，我们将暴露的动物分成两组。一个直接接触富含 AgNPs 的污泥，允许它们以它为食，第二组通过过滤器与污泥分离，仅允许潜在释放的 AgNPs 或离子间接接触。使用（单粒子）电感耦合等离子体质谱法以及相关显微镜法检查暴露 7 天的动物的总和纳米颗粒 Ag 含量。因此，我们能够证明，少量的 AgNP 仅存在于与富含 AgNP 的污泥直接接触的动物中，并且仅存在于肠道区域。通过相关显微镜没有观察到 AgNPs 从肠道转移到动物组织中。然而，