Long-term mining-zinc contamination and remediation effectiveness of stream sediments in the Galena Watershed, SW-Wisconsin and NW-Illinois

Authors: Mark W Bowen, UW Oshkosh, Dylan A King*, Missouri State University, Robert T Pavlowsky, Missouri State University, Scott A Lecce, East Carolina University, Douglas J. Faulkner, UW Eau Claire, Peter M Jacobs, UW Whitewater
Topics: Geomorphology, Water Resources and Hydrology
Keywords: Sediment contamination, Zn-Pb Mining, Remediation, Upper Mississippi Valley Zn-Pb district, Galena River Watershed
Session Type: Poster
Day: 4/12/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

Alluvial sediments within the Galena River Watershed were severely contaminated with heavy metals by historical zinc (Zn) and lead (Pb) mining operations during the early 1800s until 1979. Since the mines closed, there have been efforts to remediate on-site mine waste. However, the effectiveness of these clean-up efforts to reduce metal concentrations in stream sediments is unknown. This study compares present-day (2017) contamination trends in the Galena River Watershed to trends reported 25 years ago. A total of 415 sediment/soil samples were collected and analyzed using X-ray florescence spectrometry to determine sediment metal concentrations. The highest concentrations of zinc measured were 23,577 ppm in the channel bed, 19,825 ppm in the channel banks, and 51,273 ppm in tailings. Zinc concentrations averaged 198 ppm within the unmined Madden Branch (n=10), 2,057 ppm within the main branch of the Galena (n=31), 9,569 ppm within the heavily mined Diggings Branch (n=11), and 26,158 ppm in tailings (n=16). Present-day results show little difference compared to 25 years ago. Stream sediments collected downstream of some large-scale remediation projects such as at Vinegar Hill and Champion Mines have shown significant decreases in Zn concentrations. However, metal concentrations below other remediation sites remained elevated. Even with continued efforts to remediate contaminated sediments in the Galena River, high concentrations of Zn will persist well into the future. Sources of continued contamination include the release of stored mine wastes from floodplain deposits as well as remobilization of remaining tailings.

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