Mechanisms Triggering Metal Release From Floodplain Soils and Sediments, Three Nations Creek, Ontario, Canada

摘要

Three Nations Creek (TNC) is an intermittent tributary that runs roughly 6 km past the Xstrata Copper-Kidd Metallurgical Site to the Porcupine River. The creek historically received surface runoff, and drainage that contributed to elevated concentrations of metals including Zn and Cu, in the floodplain soils and sediments of the creek. Containment measures for surface water installed in the late 1990's and early 2000 have been successful in reducing concentrations of metals in the creek water with no toxicity issues; however, concentrations in the creek can increase with occasional toxicity events, during spring freshet and autumn periods. The severity and duration of these events differs with the season and varies with extremes in climatic events. Kidd Metallurgical Site initiated development of a Remedial Action Plan for TNC with reference to the occasional high concentration events in the creek. The objectives of this study were to identify the fundamental mechanisms that trigger seasonal metal release from the TNC floodplain and to identify measures to reduce or eliminate, to the extent practicable, conditions within TNC that result in occurrences of high concentrations of metals in the creek water. Testing results and monitoring in development of the remedial strategy are presented.