Remediation Effectiveness for Mining Sites: Hysteresis and Metal Mixtures Effect

在几乎所有的生态系统中，金属都以混合物的形式存在，在采矿现场尤其如此。准确评估金属暴露及其对人类和生态系统的影响必须考虑到混合效应，这些混合效应可能是可加性的、小于可加性的或大于可加性的。然而，目前的监管和管理做法通常针对单个金属，因为还没有足够的工具来预测混合物的生物利用度和毒性。我们的长期目标是通过提高测量、理解和预测由环境污染引起的金属混合物的生物利用度和毒性的能力来解决这一缺点。在这项工作中，我们提出了三个具体项目。首先，我们将通过开发“水母”采样器来获取水/沉积物系统中的游离金属浓度，从而解决金属生物利用度分析测量中的主要挑战。实验将在实验室进行，并在中城/克利尔克里克超级基金现场部署采样器。其次，我们将基于混合金属，多位点生物配体模型（MMMS BLM）进一步开发金属混合物对水生生物个体物种的毒性模型。这将通过使用从现场收集的简单溶液和水样进行实验室D. magna毒性测试来完成。第三个目标是将从前两个目标获得的程序和信息与测量金属混合物对在实验室建立的溪流微观环境中接触混合物的水生群落的更复杂影响结合起来。我们还将在一条受金属污染的河流中进行“自然实验”，并在安装降低金属浓度的处理系统之前、期间和之后检查反应。因为像铁这样的一些金属可能对溪流中的水生无脊椎动物和鱼类有毒，但也会使其他金属的生物可利用性降低（即具有保护作用），我们预计随着处理系统减少铁负荷，溪流的恢复会出现滞后。最终，我们希望在这个项目中改进评估方法，为保护人类和生态系统的健康提供更好的手段。

DESCRIPTION (provided by applicant): SUMMARY In almost all ecosystems, metals occur in mixtures, this is especially true at mining sites. Accurate assessment of metal exposure and effects to humans and ecosystems must account for mixture effects, which could be additive, less than additive, or more than additive. However, current regulatory and management practices usually address individual metals, because adequate tools are not yet available for predicting bioavailability and toxicity of mixtures. Our long-term objective is to address this shortcoming by improving the ability to measure, understand, and predict bioavailability and toxicity of metal mixtures arising from environmental contamination. We have proposed three specific projects in this work. First, we will solve a major challenge in analytical measurement of metal bioavailability by developing the "gellyfish" sampler to obtain free metal concentrations in water/sediment systems. Experiments will be performed both in the laboratory and in field deployments of the sampler at the Central City/Clear Creek Superfund site. Secondly, we will further develop a model of the toxicity of metal mixtures to individual species of aquatic organisms based on a mixed- metal, multi-site biotic ligand model (MMMS BLM). This will be accomplished with laboratory D. magna toxicity tests using both simple solutions and water samples collected from the site. The third objective is to integrate the procedures and information gained from the first two objectives with measurements of more complex effects of metal mixtures on aquatic communities exposed to mixtures in stream microcosms set up in the laboratory. We will also conduct a "natural experiment" in a metal-contaminated stream and examine responses before, during and after installation of a treatment system that will decrease concentrations of the metals. Because some metals like Fe can be toxic to aquatic invertebrates and fish in streams but can also make other metals less bioavailable (i.e., be protective), we expect to see a hysteresis in the recovery of the stream as Fe loading is decreased by the treatment system. Ultimately, in this project we expect to make improvements in assessment methods, which will provide a better means for protecting human and ecosystem health. PUBLIC HEALTH RELEVANCE: NARRATIVE Use of metals in our society has the unwanted consequence of creating vast numbers of ecosystems contaminated with mine wastes. The degree to which contaminants can be taken up by an organism, their bioavailability, must be assessed in order to know the potential harm to humans and their natural environment. In this project we make improvements in assessment methods to ultimately provide better means for protecting human and ecosystem health.