RAPID: Investigating changes to metal oxide nanoparticle stability in a contaminated stream during the initial period of remediation

已知的是，废弃矿山的污染对美国的河流造成了影响。即使在酸性矿山废水的影响通过处理消除后，河床本身仍将继续释放对水生物种有毒的金属。必须自然地清除含有金属的沉积物，才能使溪流恢复，使水生生物得以恢复，并得到社会的有益利用。沉积物主要由非常小的氧化铁纳米颗粒组成，其中可能含有砷、镉、铜、铅和锌。这些粘在河床上的小颗粒，如果由于它们表面的化学变化而在水中变得更稳定，可能会更快地被清除。一家从矿山废水中去除金属和酸的处理厂刚刚开始运营。处理过程还改变了溪水的成分，使颗粒在水中变得更稳定，从而更快地去除。这项研究将提供数据，以便更好地估计，如果进行类似的矿山废物处理，其他河流将以多快的速度恢复。附带纳米氧化铁(NP-FeOx)是在接受酸性矿井水的溪流中形成的。Np-FeOx能够传输铜、锌、砷等污染金属。2017年初，Clear Creek北福克(NFCC)的一座石灰处理厂将上线，这将极大地改变溪流的水化学。NP-FeOX的胶体稳定性取决于溶液组成(离子强度、二价阳离子、pH、DOC)，因此可能会受到影响。该项目的目标是了解NP-FeOx稳定性的变化将如何影响金属的去除。为了确定水处理厂(WTP)对水柱中NP-FeOx稳定性的直接影响，将使用SPICPMS、DLS、Zeta电位和ICP-OES研究流床中现有的Np-FeOx的分散情况。预计在污水处理厂运行初期，先前存在的NP-FeOX将从河床分散到水中，这可能会导致有毒金属浓度暂时增加。这将是长期的好处，因为这一过程可能会加速河床的恢复。这是第一次在实际的水流环境中检测纳米颗粒在可变水化学条件下的稳定性。此外，实验室实验中对pH和硬度的控制将使我们能够了解孤立的水化学变量对AMD系统中颗粒分散的影响。科罗拉多矿业学院针对当地高中生和大学高年级学生的夏季实地考察将参加研究现场的实地考察。此外，还将与上清溪分水岭基金会建立伙伴关系，让社区志愿者参与拟议的项目。

There are known impacts to streams in the United States as a result of pollution from abandoned mines. Even after the impact of the acidic mine effluents are removed by treatment, the streambeds themselves will continue to release metals that are toxic to aquatic species. The metal-containing sediments must be naturally removed in order for the stream to recover and allow both restoration of aquatic life and beneficial use by society. The sediments consist primarily of very small nanoparticles of iron oxide that can contain As, Cd, Cu, Pb, and Zn. These small particles, which have stuck to the streambed, may be more quickly removed if they become more stable in water due to changes in the chemistry of their surfaces. A treatment plant that removes the metals and acid from the mine effluents has just begun operation. The treatment process also alters the composition of the stream water in such a way that the particles may become more stable in water and, thus, removed more quickly. This study will provide data that will lead to better estimates of how quickly other streams will recover if similar mine waste treatment is performed. Incidental nanoparticulate iron oxides (NP-FeOx) are formed in streams receiving acidic mine waters. NP-FeOx is capable of transporting contaminant metals such as Cu, Zn, and As. In early 2017 a lime treatment plant will go online in the North Fork of Clear Creek (NFCC), which will dramatically alter the water chemistry of the stream. The colloidal stability of NP-FeOX is dependent on solution composition (ionic strength, divalent cations, pH, DOC) and is thus likely to be affected. The project goal is to understand how the removal of metals will be influenced by changes in the stability of the NP-FeOx. In order to determine the immediate impact of the water treatment plant (WTP) on NP-FeOx stability in the water column, the dispersion of existing NP-FeOx contained in the streambed will be studied using spICP-MS, DLS, zeta potential, and ICP-OES. It is expected that preexisting NP-FeOX will disperse from the creek bed into the water during early WTP operation, which may result in a temporary increase in toxic metal concentrations. This will be of long-term benefit, as this process may accelerate the restoration of the streambed. This is the first time that nanoparticle stability under variable water chemistry conditions has been examined in an actual stream setting. Additionally, the manipulation of pH and hardness in laboratory experiments will allow us to understand the effects of isolated water chemistry variables on particle dispersion in an AMD system. A summer field session aimed at local high school students and college seniors at the Colorado School of Mines will participate in a field session at the study site. In addition, a partnership with the Upper Clear Creek Watershed Foundation will be forged to involve community volunteers on the proposed project.