Snowpacks 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.
