CONTAMINATION OF RIPARIAN WETLANDS FROM PAST COPPER MINING AND SMELTING IN THE HEADWATERS REGION OF THE CLARK-FORK RIVER, MONTANA, USA

The headwaters region of the Clark Fork River in western Montana, U.S. A., has been the center of copper mining and smelting activities for a pproximately 120 years. Poor control of waste materials led to widespr ead contamination. High metal concentrations have been found in bed se diments of the river 381 km downstream and in reservoir sediments 500 km downstream. Fish and aquatic insects have been influenced by metal contamination, but little has been published about metal influences on riparian wetland areas, either sediments or plant species. In this st udy sediment and a dominant emergent macrophyte species (Typha latifol ia) were sampled from eight small riparian wetlands along the upper 19 0 km of the Clark Fork and from one site on an uncontaminated tributar y to the Clark Fork River. Elevated concentrations of copper, zinc, an d frequently, lead were found in plant tissues and sediments of 8 Clar k Fork sites compared to the local reference site. Total and HCI-extra ctable copper and zinc concentrations in unsieved and sieved (<60 micr on) sediment were strong and highly significant predictors of the meta l concentrations in Typha latifolia root tissues.