Biogeochemistry Research Centre, University of Plymouth , Plymouth, Devon PL4 8AA, United Kingdom.
Environ Sci Technol. 2017 Feb 21;51(4):2206-2216. doi: 10.1021/acs.est.6b05510. Epub 2017 Jan 31.
A new generation of speciation-based aquatic environmental quality standards (EQS) for metals have been developed using models to predict the free metal ion concentration, the most ecologically relevant form, to set site-specific values. Some countries such as the U.K. have moved toward this approach by setting a new estuarine and marine water EQS for copper, based on an empirical relationship between copper toxicity to mussels (Mytilus sp.) and ambient dissolved organic carbon (DOC) concentrations. This assumes an inverse relationship between DOC and free copper ion concentration owing to complexation by predominantly organic ligands. At low DOC concentrations, the new EQS is more stringent, but above 162 μM DOC it is higher than the previous value. However, the relationship between DOC and copper speciation is poorly defined in estuarine waters. This research discusses the influence of DOC from different sources on copper speciation in estuaries and concludes that DOC is not necessarily an accurate predictor of copper speciation. Nevertheless, the determination of ligand strength and concentrations by Competitive Ligand Exchange Adsorptive Cathodic Stripping Voltammetry enabled the prediction of the free metal ion concentration within an order of magnitude for estuarine waters by using a readily available metal speciation model (Visual MINTEQ).
一种基于物种形成的新一代水生环境质量标准（EQS）已经被开发出来，用于预测最具生态相关性的游离金属离子浓度，从而制定特定地点的数值。一些国家，如英国，已经通过建立新的河口和海洋水铜 EQS 朝着这一方向迈进，该 EQS 是基于贻贝类（Mytilus sp.）对铜的毒性与环境中溶解有机碳（DOC）浓度之间的经验关系。这是因为主要是有机配体的络合作用导致了 DOC 与游离铜离子浓度之间的反比关系。在低 DOC 浓度下，新的 EQS 更为严格，但在 162 μM DOC 以上，它高于以前的值。然而，DOC 与铜形态之间的关系在河口水中还没有得到很好的定义。这项研究讨论了不同来源的 DOC 对河口铜形态的影响，并得出结论，DOC 不一定是铜形态的准确预测因子。尽管如此，通过竞争配体交换吸附阴极溶出伏安法测定配体强度和浓度，使我们能够通过使用一种现成的金属形态模型（Visual MINTEQ），在河口水中对游离金属离子浓度进行一个数量级的预测。
