Natural attenuation of acqueous zinc in shallow soils over permafrost downslope of Galkeno 300 Mine Adit, United Keno Hill Mines, Central Yukon

This study investigated the natural attenuation of zinc in mine drainage at the Galkeno 300 mine site, located at the northern limit of the discontinuous permafrost zone in central Yukon Territory. The mine drainage contains -150 mg/1 Zn where it exits the mine; where these same waters enter the receiving environment of Christal Creek, the Zn concentrations have been reduced to ~2 mg/1. The research program examining this natural attenuation consisted of two phases. Phase 1 was comprised of a site investigation along with the collection of samples for chemical analyses and laboratory testing. Phase 2 consisted of laboratory characterisation and testing of samples collected during Phase 1. The Phase 1 site investigation was carried out during summer 2000. A climate station was established to monitor precipitation and temperature during the study-period. Site water balance was monitored through the erection of two weirs; inputs exceeded outputs by and average of 16%, indicating a minor degree of dilution. Water samples collected at sites along the longitudinal mine drainage flowpath showed no temporal trends, but clearly outlined a dramatic decrease in Zn concentrations with distance from the adit. Soil samples of upper organic and lower mineral horizons were collected from within and immediately adjacent to the flowpath. Chemical analysis of aliquots of these samples clearly showed elevation of Zn concentrations in samples in contact with mine drainage; upper organic horizon samples in particular were found to contain highly anomalous Zn levels.Applied Science, Faculty ofCivil Engineering, Department ofGraduat