Predicting nanoparticle fate in aquatic environments requires mimicking of ecosystem complexity to observe the geochemical processes affecting their behaviour. Here, 12 nm Au nanoparticles were added weekly to large-scale freshwater wetland mesocosms. After six months, ~70% of Au was associated with the macrophyte Egeria densa, where, despite the thermodynamic stability of Au⁰ in water, the pristine Au⁰ nanoparticles were fully oxidized and complexed to cyanide, hydroxyls or thiol ligands. Extracted biofilms growing on E. densa leaves were shown to dissolve Au nanoparticles within days. The Au biodissolution rate was highest for the biofilm with the lowest prevalence of metal-resistant taxa but the highest ability to release cyanide, known to promote Au⁰ oxidation and complexation. Macrophytes and the associated microbiome thus form a biologically active system that can be a major sink for nanoparticle accumulation and transformations. Nanoparticle biotransformation in these compartments should not be ignored, even for nanoparticles commonly considered to be stable in the environment.

预测水生环境中的纳米颗粒命运需要模仿生态系统的复杂性，以观察影响其行为的地球化学过程。在这里，每周将12 nm的金纳米颗粒添加到大型淡水湿地中观世界。六个月后，约70％的Au与大型植物埃塞俄比亚（Egeria densa）有关，尽管Au ⁰在水中具有热力学稳定性，原始的Au ⁰纳米颗粒仍被完全氧化并与氰化物，羟基或硫醇配体络合。提取生物膜上生长密花香薷叶片显示可在数天内溶解Au纳米颗粒。对于具有抗金属分类单元的患病率最低但对氰化物的释放能力最高的生物膜，Au生物溶解速率最高，已知该膜可促进Au ⁰氧化和络合。因此，大型植物和相关的微生物组形成了生物活性系统，可以成为纳米颗粒积累和转化的主要吸收者。即使对于通常被认为在环境中稳定的纳米颗粒，也不应忽略这些隔室中的纳米颗粒生物转化。