Contaminant Loading of Watersheds From Snowmelt: An Integrated Study Using Stable Isotopes and Rare Earth Elements

在整个冬季，雪堆收集和储存来自大气的酸沉积和化学污染物。在春天，这些污染物在很短的时间内被释放到流域；前30%的熔体含有高达80%的溶质。这种酸和其他化学物质的密集释放严重影响水质和水生环境。这个项目的重点是在两个设备齐全的雪实验室：加利福尼亚的中央塞拉雪实验室和佛蒙特州的斯莱夫河研究流域，对融雪的同位素和化学成分的化学和物理控制进行定量理解。将这两个地点的同位素和化学分析结合起来，将比单独使用任何一种示踪剂更能全面地了解控制融水产生的过程。稀土元素（RFTs）将被用作积雪中的化学示踪剂。这些示踪剂不仅可以识别和追踪单个降雪事件中的水，还可以提供有助于阐明剖面和融雪的数据。这将使我们能够评估雪变质作用期间积雪内部的同位素再分配，以及水沿着雪柱渗透时液冰交换对这种成分的改变。在美国陆军寒冷地区研究与工程实验室进行的冷室实验，将使我们能够监测融雪的氧同位素值作为不同融化速率和颗粒大小的函数，从而补充实地研究。野外和实验数据将用于开发和参数化同位素和化学物质通过积雪输送的物理模型。最终，从这项工作中获得的对污染物运输的理解将扩展到整个流域。

9903281FengSnowpacks collect and store acid deposition and chemical pollutants from the atmosphere throughout the winter. In the spring, these pollutants are released into watersheds in a very short time; the first 30% of melt contains up to 80% of the solutes. Such an intensive release of acid and other chemicals significantly affects water quality and aquatic environments.This project focuses on developing a quantitative understanding of the chemical and physical controls on the isotopic and chemical compositions of snowmelt at two well-equipped snow laboratories: Central Sierra Snow Laboratory in California and Sleepers River Research Watershed in Vermont. The integration of isotopic and chemical analyses of these two sites will provide a more complete understanding of the processes controlling meltwater generation than is possible when either tracer is used alone. Rare earth elements (RFTs) will be used as chemical tracers within the snowpack. These tracers will not only identify and trace water from individual snow events, but also provide data that will help elucidate the profiles and snowmelt. This will enable us to evaluate isotopic redistribution within the snowpack during snow metamorphism and the modification of this composition by liquid-ice exchange as water percolates down the snow column. Cold room experiments, conducted at the U.S. Army's Cold Regions Research and Engineering Laboratory, will complement the field studies by allowing us to monitor oxygen isotope values of snowmelt as a function of different melt rates and grain size. Both the field and experimental data will be used to develop and parameterize physically based models of isotopic and chemical transport through the snowpack. Ultimately, the understanding of contaminant transport gained from this work will be extended to entire watersheds.