U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting, Colorado Springs, Colorado, September 20-24, 1993, Water-Resources Investigations Report 94-4015

Iron and Zinc Budgets in Surface Water for a Natural Wetland Affected by Acidic Mine Drainage, St. Kevin Gulch, Lake County, Colorado

Abstract

Iron and zinc mass input and output in surface water were estimated for a wetland receiving acidic mine drainage near Leadville, Colorado, to evaluate (1) whether the wetland is removing the metals from surface water, and (2) the processes causing the observed metal fate. The results indicate that about 560 and 850 kilograms of iron were removed from surface water from late spring through fall 1988 and from late spring through midsummer 1989, respectively. Iron removal occurred primarily through settling of iron oxyhydroxide particles greater than 0.1 micrometer. The results also indicate that zinc was not removed from surface water by the wetland. All of the zinc is in the filtered fraction. Either contact time between the water and the wetland substrate is insufficient for the reactions that could remove dissolved zinc, such as sulfate reduction, to occur, or zinc removal reactions do not occur in this wetland.