Van Tuyl Lecture, October 7, 2024, Marquez 126, 12-1pm

Kenny Swift Bird, Colorado School of Mines

Geology and Geological Engineering
GE/ GP 2024 Student Research Fair Winner

Quantifying Metal(oid) Source-sink Dynamics in an Alpine Headwaters Stream

Abstract: Metal(loid) impacts to streams are pervasive across the western U.S. from both natural and legacy mining sources, impacting ecosystem function, water quality, and biodiversity. These impacts are difficult to quantify as they result from both point and diffuse loading of metals and metalloids into streams. Metal mobilization occurs on timescales ranging from events to interannual processes, imposing complexity to metal fate and transport processes across both space and time. Federal, state, and local agencies have spent billions of dollars on mine remediation over the last several decades, often with minimal water quality improvement. Delineating when, where, and how streams serve as sources or sinks for metals remains a challenge for geoscientists and mining-impacted communities. Here, we use tracer studies paired with electrical resistivity to measure surface water-groundwater exchange, surface water and hyporheic water sampling, and surface water-groundwater gradients to quantify source-sink dynamics of metal fate and transport in an alpine, mining-impacted watershed. We use concentration-discharge relationships and hyporheic reaction potential, a new metric based on data from tracer studies and geochemical sampling, to quantify governing processes of aluminum, iron, manganese, and zinc fate and transport. Preliminary results suggest that SW-GW connectivity varies greatly over a relatively short reach (~5 km), with upstream portions of the stream acting as a metal source and downstream portions acting as a metal sink. The hyporheic zone is not ubiquitous across the study reach, with tracer studies showing minimal exchange and surface water-groundwater connectivity in the upstream portions of the watershed relative to downstream. Results from this work have implications for mine remediation, water quality, and ecosystem function in mining-impacted watersheds.

This lecture is scheduled in a hybrid format. If you would like to join the meeting please:

Join from PC, Mac, Linux, iOS or Android: https://mines.zoom.us/j/94648111771?pwd=H5fLUI4blbtLZnHrYHn8vAWRLfSHeW.1
Meeting ID: 946 4811 1771
Password: 047204

Refreshments will be served.