沉积物毒性鉴别评估技术在一个有着多重污染物输入地点的应用

沉积物毒性鉴别评估用于确定造成沉积物整体毒性测试中观察到有害效果的原因。然而在多污染物的情况下，将总体毒性划分为为不同个体污染物单独造成的毒性的方法存在很多问题。利用一个有着多重输入与相关污染物的站点数据，我们为毒性鉴别评估提出一种通过追踪毒性单位（TUs）来确定是否囊括全部毒性的方法。首先确定出沉积物整体的毒性水平，然后将毒性来源划分至几种污染物大类，例如氨类，金属，非极性有机物等。本文中毒性很大程度上来源于非极性有机物，所以在萃取沉积物之后，将萃取物重新加回稀释水中以检测毒性的复原。每一部分污染物的毒性占比由溶剂梯度测量，并进行毒性检测。目标占比由气相色谱-质谱分析得到，从而鉴定出与特定成分相关的毒性。之后对这些成分相关的毒性单位进行测定以确定可能的原因组合和是否已囊括全部毒性。数据表明毒性既与已有化合物相关，又与新兴污染物相关，而两种污染物对于总体毒性的具体贡献则随实验地点改变。
精选自Howard C. Bailey, Catherine A. Curran, Peter Arth, Bonnie P. Lo, Rich Gossett. Application of Sediment Toxicity Identification Evaluation Techniques to a Site with Multiple-Contaminants. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2456–2465, October 2016.DOI: 10.1002/etc.3488
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Application of Sediment Toxicity Identification Evaluation Techniques to a Site with Multiple-Contaminants

Sediment TIEs are conducted to determine causes of adverse effects observed in whole sediment toxicity tests. However, in multiple contaminant scenarios, it is problematic to partition contributions of individual contaminants to overall toxicity. Using data from a site with multiple inputs and contaminants of concern, we describe a quantitative approach for the TIE process by tracking toxic units (TUs) to determine whether all toxicity is accounted for. The initial step established the level of toxicity associated with the whole sediment, and then partitioned sources of toxicity into general contaminant classes (e.g., ammonia, metals, non-polar organic compounds). In this case, toxicity was largely due to non-polar organics, so the sediments were extracted and the extracts added back into dilution water and tested to confirm recovery of toxicity. Individual fractions were then generated using a solvent gradient and tested for toxicity. Fractions of interest were evaluated with GC/MS to identify specific constituents associated with toxicity. TUs associated with these constituents were then evaluated to determine probable associations with cause, and whether all toxicity was accounted for. The data indicated that toxicity was associated with two contaminant classes, representing legacy compounds and contaminants of emerging concern, with the contribution of each varying across the site.
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