HR: 1340h
AN: B13C-1377 INVITED    [Abstracts]
TI: Reach Scale Studies of Trace Metal Transport in Mountain Streams: Do Wetlands Act as a Sink or a Source?
AU: * McKnight, D M
EM: diane.mcknight@colorado.edu
AF: University of Colorado, 1560 30th St, Boulder, CO 80309, United States
AU: August, E
EM: ericaugust@gmail.com
AU: Duren, S
EM: SDuren@BrwnCald.com
AF: University of Colorado, 1560 30th St, Boulder, CO 80309, United States
AU: Wong, J
EM: jeffrey.wong@colorado.edu
AF: University of Colorado, 1560 30th St, Boulder, CO 80309, United States
AB: In the Rocky Mountains, there are many watersheds containing streams impacted by acid rock and acid mine drainage. These streams typically have high concentrations of dissolved metals and copious amounts of iron and aluminum oxides deposited on the streambed. Remediation of these contaminated streams is challenging because of the remote locations of the abandoned mines and the large amounts of metal oxides potentially generated in treatment of the drainage. Wetlands have the potential to attenuate trace metal transport. We examined retention of metals in an iron-oxide rich wetland near Leadville, CO, which had been receiving mine drainage for almost a century. We found that in the summer, the wetland did have a net retentive effect for most metals studied, limiting input into the adjacent stream, whereas, the wetland was a net source of metals during the winter. Furthermore, during spring snowmelt, the wetland did not retain the large pulse of zinc and iron leached by melting snow on the surrounding tailings piles. In another stream system receiving acid rock drainage, we found that riparian wetlands become sources of metals to the stream under drought conditions, which further exacerbated the metal enrichment associated with lesser snowmelt dilution.
DE: 0478 Pollution: urban, regional and global (0345, 4251)
DE: 0483 Riparian systems (0744, 1856)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting