During nanoparticle environmental exposure, presence in the water column is expected to dominate long distance transport as well as initial aquatic organism exposure. Much work has been done to understand potential ecological and toxicological effects of these particles. However, little has been done to date to understand the comparative persistence of engineered particles in realistic environmental systems. Presented here is a study of the water column lifetimes of 3 different classes of nanoparticles prepared with a combination of surface chemistries in wetland mesocosms. We find that, when introduced as a single pulse, all tested nanoparticles persist in the water column for periods ranging from 36 h to 10 days. Specifically, we found a range of nanoparticle residence times in the order Ag > TiO₂ > SWCNT > CeO₂. We further explored the hypothesis that heteroaggregation was the primary driving factor for nanoparticle removal from the water column in all but one case, and that values of surface affinity (α) measured in the laboratory appear to predict relative removal rates when heteroaggregation dominates. Though persistence in the water column was relatively short in all cases, differences in persistence may play a role in determining nanoparticle fate and impacts and were poorly predicted by currently prevailing benchmarks such as particle surface preparation.

中文翻译：

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工程纳米颗粒在复杂水生生态系统中的比较持久性

在纳米颗粒环境暴露期间，预计水柱中的存在将主导长距离运输以及最初的水生生物暴露。为了了解这些颗粒的潜在生态和毒理作用，已经做了很多工作。但是，迄今为止，对于了解现实环境系统中工程粒子的相对持久性还很少做。这里介绍的是对三种不同类别的纳米颗粒在湿地中观宇宙中结合表面化学方法制备的水柱寿命的研究。我们发现，当以单脉冲形式引入时，所有测试的纳米颗粒都将在水柱中保留36 h至10天。具体而言，我们发现纳米粒子的停留时间范围为Ag> TiO ₂> SWCNT> CeO ₂。我们进一步探讨了以下假设：杂聚是在除一种情况以外的所有情况下从水柱中去除纳米颗粒的主要驱动因素，并且实验室中测得的表面亲和力（α）值似乎可以预测杂聚占主导时的相对去除率。尽管在所有情况下水柱中的持久性都相对较短，但持久性差异可能在确定纳米颗粒的命运和影响方面起作用，并且当前流行的基准（如颗粒表面制备）对这种持久性的预测较差。