Dissolved organic matter characterization and metal speciation in boreal streams

北方河流中溶解有机物的表征和金属形态

• 批准号: 341931-2008
• 负责人: Guéguen, Céline
• 金额: $ 1.09万
• 依托单位: Trent University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=496990
• 关键词: Dissolved; organic; matter; characterization; metal

Trace metals in the environment can provide either benefits or risks to aquatic life and humans. They may arise naturally or result partly or wholly from man-made pollution. It is no longer adequate, however, to consider only the total metal concentration in order to assess risk/benefit. Rather, it is necessary to determine the physicochemical forms (i.e. speciation) of an element because different forms of the same metal can range from essential to innocuous to strongly toxic. The modeling of metal speciation permits exploration into the processes of mobility, transport, toxicity and bioavailability of metals in water. Its application to natural aquatic ecosystems, however, is often limited due to the presence of dissolved organic matter (DOM), the main ligand for metal complexation. It is normally assumed in modeling calculations that all DOMs, regardless of their nature and origin, behave in a similar way toward complex trace metals. The diversity and variability of DOM within a specific environment depend on the potential origins of the DOM as well as on the hydrological conditions in the watershed. A better understanding of DOM cycling is required to predict how metal speciation will affect fate and bioavailability of metals in aquatic environments. The boreal shield ecozone is a particularly important and sensitive region of Ontario where most of its streams and lakes are located. In this project, a metal speciation model will be developed and tested against field observations to predict how the metal speciation will affect fate and bioavailability of water-borne metals in boreal streams. The spatial and temporal change in DOM, as well as those in the metal speciation, will be investigated in two boreal streams of south-central Ontario. Laboratory experiments will be designed to investigate the influence of DOM dynamics and composition on metal binding properties. These experimental results will be incorporated into a model that describes the importance of DOM in metal speciation. This model will allow a synthesis of the overall effects of the DOM-metal associations and of their changes as the qualitative and quantitative character of the DOM varies in the study systems.

环境中的微量金属对水生生物和人类既有好处，也有风险。它们可能是自然产生的，也可能部分或全部是人为污染造成的。然而，仅考虑总金属浓度以评估风险/获益已不再足够。相反，有必要确定一种元素的物理化学形式（即物种形成），因为同一种金属的不同形式可以从必需到无毒到剧毒。金属形态的模拟允许探索的流动性，运输，毒性和生物利用度的金属在水中的过程。然而，由于存在溶解性有机物（DOM），金属络合的主要配体，其在自然水生态系统中的应用往往受到限制。在建模计算中，通常假设所有DOM，无论其性质和来源如何，都以类似的方式对复杂的痕量金属起作用。特定环境中DOM的多样性和变异性取决于DOM的潜在来源以及流域的水文条件。更好地了解DOM循环需要预测金属形态将如何影响水生环境中的金属的命运和生物利用度。北方盾生态区是安大略的一个特别重要和敏感的区域，安大略的大部分河流和湖泊都位于该区域。在这个项目中，将开发一个金属形态模型，并根据实地观察进行测试，以预测金属形态将如何影响北方河流中水生金属的命运和生物利用度。DOM的时空变化，以及在金属形态，将在两个北方流的中南部安大略。实验室实验将被设计来研究DOM动态和组成对金属结合性能的影响。这些实验结果将被纳入一个模型，描述DOM的金属形态的重要性。该模型将允许DOM-金属协会的整体效果和它们的变化的DOM的定性和定量特征的研究系统中的变化的合成。