Progress in Establishing Wetland Plants in Permanently Flooded UraniumTailings

Abstract

Trials are taking place on flooded pyritic uranium tailings near the city of Elliot Lake, Ontario to establish deep water aquatic plants. It is anticipated that the wetland eventually formed will produce organic matter that will hinder oxygen penetration into the tailings and help to keep acid production to a minimum. In 1993, plots and vegetation islands of cattail, common reed, beaked sedge and wool rush were transplanted into water less than 0.75 m deep. By 1995, these plants had overcome any transplant shock and islands of several species were expanding. In 1995, a large scale transplant was undertaken to establish vegetation in deeper water. A total of 50 sites of varying depths were established within Rio Algom Limited's Quirke Waste Management Area (WMA). These sites were planted during the month of August with 10 units of plant material with substrate from their source wetland. The term ‘unit‘ represents 2 different planting methods. One method involved placing plant roots/rhizomes and substrate in a biodegradable burlap bag and the other being direct planting, into the tailings substrate. White water lily, pickerel weed, pondweed, watershield, hardstem bulrush and bladderwort were planted in 50 locations ranging in depth from 0.34-4.53 m. Each planting unit received approximately 70 g of bonemeal (2- 11 -0) at the time of planting. Survival rates near 40% were recorded for fragrant water lily, and 80% for bath pickerel weed and hardstem bulrush. Watershield survival was minimal at 10%. Pondweed and bladderwort transplants were not successfully transplanted. Transplants were relocated and survived in Cell 14 only as turbidity levels were extremely high in Cell 15 the year of and the year following transplant. Analytical results with respect to elemental, nutrient and radionuclide concentrations in plants, substrate and water are presented for source sites and the large scale transplant in the WMA cells.