Civil and Environmental Engineering Department , Duke University , Durham , 27708 North Carolina , United States.
Center for the Environmental Implications of Nanotechnology , Duke University , Durham , 27708 North Carolina , United States.
Environ Sci Technol. 2018 Apr 3;52(7):4072-4078. doi: 10.1021/acs.est.7b06142. Epub 2018 Mar 13.
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 > TiO > SWCNT > CeO. 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.
在纳米颗粒的环境暴露中，预计它们在水柱中的存在将主导远距离运输以及水生生物的初始暴露。已经进行了大量工作来了解这些颗粒的潜在生态和毒理学影响。然而，迄今为止，对于了解工程颗粒在实际环境系统中的比较持久性的研究还很少。本文介绍了在湿地中观测试验箱中使用组合表面化学方法制备的 3 种不同类型纳米颗粒在水柱中的寿命研究。我们发现，当作为单一脉冲引入时，所有测试的纳米颗粒在水柱中的存在时间从 36 小时到 10 天不等。具体而言，我们发现纳米颗粒的居留时间顺序为 Ag > TiO > SWCNT > CeO。我们进一步探讨了这样一种假设，即除了一种情况外，异质聚集是纳米颗粒从水柱中去除的主要驱动因素，并且在异质聚集占主导地位时，在实验室中测量的表面亲和力（α）值似乎可以预测相对去除率。尽管在所有情况下，在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发挥作用，并且目前流行的基准（例如颗粒表面制备）对其预测效果很差。
