HR: 0800h
AN: H41A-0284 INVITED     [Abstracts]
TI: Modeling the Geochemistry of Red Mountain Creek, Colorado, With Implications for Premining conditions
AU: * Runkel, R L
EM: runkel@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center PO Box 25046, MS 415, Denver, CO 80225 United States
AU: Kimball, B A
EM: bkimball@usgs.gov
AF: U.S. Geological Survey, 2329 W Orton Cir, West Valley, UT 84119-2047 United States
AU: Walton-Day, K
EM: kwaltond@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center PO Box 25046, MS 415, Denver, CO 80225 United States
AU: Verplanck, P L
EM: plv@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center Mail Stop 964, Denver, CO 80225 United States
AB: In August of 2002, a synoptic water-quality study was conducted on Red Mountain Creek, an acid mine drainage stream in southwestern Colorado. Data from the study were used to calibrate OTEQ, a reactive solute transport model for streams and small rivers. OTEQ is formed by coupling the OTIS solute transport model with a chemical equilibrium submodel. The submodel is based on MINTEQ, a model that calculates the distribution of aqueous species under chemical equilibrium. The coupled model considers a variety of processes including advection, dispersion, transient storage, transport and deposition of water-borne solid phases, acid/base reactions, complexation, precipitation/dissolution, and sorption. Application of OTEQ to the low-flow dataset from Red Mountain Creek suggests that surface-water sources account for observed changes in stream geochemistry and that most solutes are transported conservatively throughout the study reach. Mass balance calculations and simulation results indicate that four mining-related sources account for 83, 70, and 69 percent of the observed metal loading for aluminum, arsenic, and zinc, respectively. A hypothetical estimate of premining water quality is obtained by performing an additional simulation in which the the four mining-related sources are replaced with a source that represents natural background. Simulation results suggest improved water quality under premining conditions, with increased pH, lower metal concentrations, and non-conservative transport. Despite this hypothetical improvement, dissolved metal concentrations remain elevated and pH remains below 5.0. This finding supports the idea that Red Mountain Creek was acidic and metal-rich prior to mining.
UR: http://co.water.usgs.gov/otis
DE: 1806 Chemistry of fresh water
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting