(EGB) Influence of Natural Colloids on Speciation and Chemical Mobility of Trace Metals Transported from Contrasting Watersheds

[997544 . 44]流域在调节湖泊和溪流的微量金属状态方面起着重要作用。金属出口通过与微量金属载体，特别是悬浮颗粒物质和天然有机物的联系，与流域特征、水文和生物地球化学过程有关。然而，要了解金属从流域的迁移，除了它们的产量和浓度外，还需要关于金属的化学形式（形态）的信息。特别值得关注的是水和胶体金属形态的性质，以及与水和胶体配体（载体）结合的金属是不稳定的（生物可利用的）还是稳定的。我们的前提是，与水和胶体配体相关的金属在溪流中的倾向性可以表征并与流域特征相联系。我们的目标是量化和模拟从不同流域出口的微量金属的关键化学形式及其与流域过程和特征的联系。具体目标是：(1)确定金属在水相和胶体相中在稳定和不稳定形态之间的分配以及不稳定形态的动态行为；(2)量化控制金属结合的配体的突出特征以及这些属性与分水岭特征的联系；(3)对微量金属与水相和胶体相结合的关键状态变量的影响进行排序和量化。(4)将天然水性和胶体配体纳入一个框架中，以模拟不稳定金属的形态和动力学以及与流域特征和过程的耦合。我们的方法表征了一组微量金属与来自不同流域的代表性天然水性和胶体配体的相互作用。金属之间的比较将用于探测配体的性质。将选择流域，提供关键的水性和胶体载体（溶解的有机碳；铁和铝氧化物）的特定组合。将使用地理信息系统方法将金属物种形成与流域特征和过程联系起来。这项工作得到了地球科学理事会的地球科学（水文学）司、数学和物理科学理事会的化学司和多学科活动厅以及工程理事会的化学和运输系统司的支助。

9975444ArmstrongWatersheds play a major role in regulating the trace metal status of lakes and streams. Metal export has been related to watershed characteristics, hydrology, and biogeochemical processes through linkages to trace metal carriers, especially suspended particulate matter and natural organic matter. However, understanding metal transport from watersheds requires information on the chemical forms (speciation) of the metals in addition to their yields and concentrations. Of special concern is the nature of aqueous and colloidal metal forms and whether metal bound to aqueous and colloidal ligands (carriers) are labile (bioavailable) or stable. Our premise is that the liability of metals associated with aqueous and colloidal ligands in streams can be characterized and linked to watershed characteristics.Our goal is to quantify and model key chemical forms of trace metals exported from contrasting watersheds and their linkages to watershed processes and characteristics. Specific objective are to (1) determine the partitioning of metals in aqueous and colloidal phases between labile and stable forms and the dynamic behavior of labile forms, (2) quantify prominent characteristics of ligands controlling metal binding and the linkages of these properties to watershed characteristics, (3) rank and quantify the influence of key state variables on trace metal association with aqueous and colloidal phases, and (4) incorporate natural aqueous and colloidal ligands into a framework for medeling the speciation and dynamics of labile metals and the coupling to watershed characteristics and processes.Our approach characterizes the interaction of a suite of trace metals with representative natural aqueous and colloidal ligands from contrasting watersheds. Comparisons among metals will be used to probe ligand properties. Watersheds will be selected to provide specific combinations of key aqueous and colloidal vector (dissolved organic carbon; Fe and Al oxides). A geographic information systems approach will be used to link metal speciation to watershed characteristics and processes.The work is being supported by the Division of Earth Sciences (Hydrology) in the Directorate for Geosciences, the Division of Chemistry and the Office of Multidisplinary Activities in the Directorate for Mathematical and Physical Sciences, and the Division of Chemical and Transport Systems in the Directorate for Engineeing.