Remediation Effectiveness for Mining Sites: Hysteresis and Metal Mixtures Effect

摘要 在几乎所有的生态系统中，金属以混合物的形式存在，在矿场尤其如此。 准确评估金属暴露及其对人类和生态系统的影响必须 考虑混合效应，可以是相加的、小于相加的或大于 添加剂。然而，目前的监管和管理做法通常涉及 个别金属，因为目前还没有足够的工具来预测 混合物的生物利用度和毒性。我们的长期目标是解决这个问题 通过提高测量、理解和预测生物利用度的能力 以及环境污染引起的金属混合物的毒性。我们有 提出了这项工作中的三个具体项目。一是破解一项重大挑战 研制“冻鱼”采样器进行金属生物有效性的分析测量 获取水/沉积物系统中的游离金属浓度。实验将是 在实验室和中心现场部署采样器的情况下执行 城市/Clear Creek超级基金网站。其次，我们将进一步开发一个模型， 金属混合物对水生生物个体物种的毒性 金属，多位生物配基模型(MMMS BLM)。这将通过以下方式实现 使用简单溶液和水样进行的实验室D.Magna毒性测试 从网站上收集的。第三个目标是将程序和 从前两个目标获得的信息，其衡量标准更为复杂 溪流中金属混合物对水生植物群落的影响 在实验室里建立的缩影。我们还将在一个 金属污染流，并在安装前、安装期间和安装后检查响应 一种可以降低金属浓度的处理系统。因为有些人 像铁这样的金属对水生无脊椎动物和溪流中的鱼都是有毒的，但也可以 其他生物可利用性较低的金属(即具有保护性)，我们预计在 该处理系统降低了铁负荷时的回收率。最终，在 这个项目我们希望在评估方法上有所改进，这将提供 一种保护人类和生态系统健康的更好手段。

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.