From Landscape to Flood Plain: An Examination of Dissolved and Colloidal Trace Elements in the Yukon River Basin

EAR-0617607艾伦·M·希勒我们提出了一项关于育空河水系中溶解和胶体微量元素的研究，以及DOC的浓度和性质与微量元素的关系。溶解和胶体微量元素将在盆地内代表主要地貌/环境(如冰川系统、以永久冻土为主的系统等)的各种小流域中进行测定。以及地质的可变性。溶解有机碳(DOC)将通过与G.Aiken(美国地质勘探局)的合作进行分析和表征。实验将考察具有不同颗粒和DOC特征的支流混合过程中痕量元素和DOC的行为。将研究溶解的微量元素在不稳定组分和有机络合组分之间的分配。将对胶体颗粒的凝胶迁移率进行检测，以更好地确定有机物与无机胶体的相互作用。智力优势：一般缺乏关于溶解和胶体微量元素的通量以及控制这些通量的过程的基本信息，特别是在相对原始的系统和高纬度系统，如育空河流域。将微量元素工作与DOC表征相结合的研究更是少见，尽管DOC在控制许多微量元素的溶解和胶体浓度方面很重要，而且铁等元素在影响有机物方面也很重要。育空系统之所以特别令人感兴趣，还有许多其他原因，包括盆地内存在广泛的湿地、冰川和永久冻土；其极端温度范围；以及河流的季节性冰盖--所有这些都可能是微量元素流动和运输的因素。通过比较育空盆地内冰川、冻土、湿地和其他自然因素的不同子系统，可以深入了解景观对微量元素活化的影响。将育空地区的微量元素地球化学与温带和热带系统的微量元素地球化学进行比较，将表明高纬度系统的微量元素通量是否/为什么不同于低纬度系统，并可能为典型的冰川和间冰期系统提供有用的类比。在育空盆地内，比较相似的冰化和未冰化的子系统也可以提供有用的冰期/间冰期类比，并使我们能够检查冰川系统的相对微量元素化学风化产额。尤其重要的是，育空盆地对气候变暖特别敏感，气候变暖预计会融化永久冻土、缩小湿地、干燥土壤，并延长生长季--这些因素同样会影响微量元素的流动。如果我们能够将某些化学物质的浓度、比例或变化与特定类型的景观(例如，冰川或永久冻土为主的盆地)联系起来，那么我们就有了一个综合监测北极流域景观变化的工具，例如可能随着气候变化而发生的变化。我们提供了支持这一概念的初步数据，但也指出了为什么需要进一步的数据。育空河流域非常适合作为模式系统，因为我们可以隔离冰川和永久冻土相关的影响，并以确定对系统的控制所需的频率获取样本。广泛的影响：这项工作的结果将适用于三个对社会普遍有益的领域。首先，通过了解水质自然时间变异性的性质和原因，监测程序可以更好地设计其采样策略。其次，如果我们的河流化学比较提供了一个参照系，以了解在人类干扰的系统中应该是什么“自然”浓度，那么这将与那些试图建立河流污染限制的工作人员有关。最后，我们的工作应该使我们能够理解流域的变化(包括气候变化)如何影响溪流化学，从而成为使用溪流化学监测流域状况的基础。其他影响包括：国际和平协会将研究与教学相结合；他有本科生参与研究的历史；对两名研究生进行了教育/培训；与当地学校进行了合作抽样工作；加强了与美国地质调查局研究人员的合作；通过国际和平协会的网站广泛传播信息，并在育空河流域的土著村庄非正式地公开传播信息。

EAR-0617607Alan M. SHILLERWe propose a study of dissolved and colloidal trace elements in the Yukon River system and the relationship of DOC concentration and character to the trace elements. Dissolved and colloidal trace elements will be determined in a variety of mainly small catchments within the basin, representing major landscapes/environments (e.g., glacial systems, permafrost-dominated systems, etc.) as well as geological variability. Dissolved organic carbon (DOC) will be analyzed and characterized through a collaboration with G. Aiken(USGS). Experiments will be performed to examine the behavior of trace elements and DOC during mixing of tributaries having different particle and DOC character. The partitioning of dissolved trace elements between labile and organic-complexed fractions will be examined. The electrophoretic mobility of colloidal particles will be examined to better ascertain the interaction of organic matter with inorganic colloids.Intellectual Merit: Basic information on the fluvial fluxes of dissolved and colloidal trace elements and the processes controlling those fluxes is generally lacking, especially in relatively pristine systems and in high latitude systems such as the Yukon River Basin. Studies that combine trace element work with DOC characterization are even less common, despite the importance of DOC in controlling the dissolved and colloidal concentrations of many trace elements as well as the importance of elements such as Fe in affecting organic matter. The Yukon system is particularly interesting for a number of other reasons including the presence of extensive wetlands, glaciers, and permafrost within the basin; its extreme temperature ranges; and the seasonal ice cover of the rivers-all of which can be factors in trace element mobilization and transport. Insight into the effect of landscape on trace element mobilization could be gained by comparingsub-systems within the Yukon Basin differing in glaciation, permafrost, wetlands and other physiographic factors. Comparison of the trace element geochemistry of the Yukon with that of temperate and tropical systems will indicate whether/why trace element fluxes from high latitude systems differ from low latitude systems and may provide a useful analogy between typical glacial and interglacial systems. Within the Yukon Basin, comparison of similar glaciated and unglaciated subsystems could also provide a usefulglacial/interglacial analogy and allow us to examine the relative trace element chemical weathering yield of glaciated systems. Especially important is that the Yukon Basin is particularly sensitive to climate warming which can be expected to thaw permafrost, shrink wetlands, dry soils, and lengthen the growing season-factors which, again, can affect trace element mobilization. If we can associate certain chemical concentrations, ratios, or variabilities with specific types of landscapes (e.g., glacial versus permafrost-dominated basins) then we will have a tool for integrated monitoring of landscape changes in arctic watersheds such as might occur with climate change. We present preliminary data supporting this concept but also indicate why further data are required. The Yukon River basin is well suited to serve as a model system since we can isolate both glacial and permafrost related influences and obtain samples at a frequency required to define controls on the system.Broader Impacts: Results of this work will be applicable in three areas of general benefit to society. First, by understanding the nature and causes of natural temporal variability in water quality, monitoring programs can better design their sampling strategies. Second, if our river chemistry comparisons provide a frame of reference for understanding what should be the "natural" concentrations in human-disturbed systems, then this will be pertinent to those workers trying to establish fluvial pollution limits. Finally, our work should allow an understanding of how changes in watersheds (including climate change) can affect stream chemistry and thus serve as a basis for using stream chemistry to monitor the state of a watershed. Additional impacts include the PI's integration of research and teaching; his history of involvement of undergrads in research; the education/training of two graduate students; a collaborative sampling effort with a local school; an enhanced collaboration with a USGS researcher; and the broad dissemination of information through the PI's web site as well as informal public dissemination of information in native villages within the Yukon River Basin.