Seasonal Changes In Biogeochemistry Of Natural Wetland Receiving Drainage From An Abandoned Mine
Abstract
Abandoned mines from the mining boom in the Rocky Mountains (1880-1930) are now sources of acidity and metals throughout the region. Because of their remote location and extreme conditions during winter, remediation of these mines poses many challenges. Removal of tailings piles and construction of artificial wetlands have used at some sites. We studied the seasonal variation in metal mass flows in a natural wetland that receives drainage from a mine tunnel and then drains into a mountain stream. The wetland has thick deposits of iron oxides and dissolved iron entering the wetland is generally retained in the upper reaches of the wetland through rapid oxidation and precipitation of iron oxides. For manganese and zinc the retention processes are sorption on iron oxides, precipitation of sulfides and uptake by wetland plants. During summer, the wetland acts as a net sink for Mn and Zn, but in winter the wetland is a net source, augmenting the metal flux to the stream. Further, a pulse of snowmelt from the surface of the tailings piles contributed a large amount of the annual metal load during a 1-2 month period, and this pulse moved rapidly through the wetland into the stream. These results show that the interaction of hydrologic and biogeochemical processes control the long term effectiveness of wetlands in reducing metal loads from abandoned mines.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM...B22A03M
- Keywords:
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- 1615 Biogeochemical processes (4805)