Impacts of mining on a subalpine lake in the central Colorado Rocky Mountains

Authors: Bethany Walker*, University of Colorado Denver, Christy Briles, University of Colorado Denver
Topics: Paleoenvironmental Change, Biogeography, Human-Environment Geography
Keywords: diatoms, sediment geochemistry, mining, southern Rocky Mountains
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

The long-term impacts and ecosystem recovery following mining activity are not well understood. This study examines terrestrial and aquatic ecosystems before and after mining activity in a subalpine lake ecosystem in the central Colorado Rocky Mountains. A 1-meter-long sediment core from Lily Pond was analyzed for freshwater diatoms, pollen, charcoal, and geochemistry to reconstruct aquatic communities, vegetation, burning and heavy metal inputs, respectively. The Forest Hill Mine operated upstream of Lily Pond from 1880-1920, with a short break from 1907-1916. Lead-210 dating of the last 150 years and high-resolution proxy sampling of the mine period will allow an estimation of recovery during the mine operation break and the time following its shut down. The decade halt in mining provides another temporal period to examine ecosystem recovery to pre- and post- mining conditions. Initial results indicate a shift from epiphytic and epipelic diatoms towards Fragilaria during the mining period, suggesting increased sedimentation and turbidity. Geochemistry data indicate an increase in metals and magnetic susceptibility, suggesting allochthonous inputs possibly from the mine. Charcoal increases while percentages of arboreal pollen decrease, indicating an increase in burning and decrease in arboreal vegetation. These distinct changes suggest that ecosystems in and round Lily Pond were significantly altered by the mining activity.

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