Release of Base and Potentially Harmful Metals from Waste Deposits at a Former Uranium Mine in Eastern Finland

Leaching of metals (Fe, Mn, Cu, Co, Ni, Zn, Cr, Cd, Pb) and arsenic from mine wastes and their accumulation in waters, soils and sediments have been determined at the former Paukkajanvaara uranium mine in Eastern Finland. A small-scale test mine, operating in 1959-1960, generated 7,300m3 of waste rock and 12,000m3 of mill tailings, which were covered with soil and till in the early 1990s. These two materials, waste rock and mill tailings, were studied as possible sources for metal contamination in surrounding water systems. Water samples from a nearby pond and streams flowing from the site into the pond were collected. In addition, soil, pond sediment and mill tailings samples were taken and metals were leached from them with strong acids. Metal concentrations in the water samples and acid leachates were measured with ICP-MS. Nickel and arsenic concentrations in stream water were seen slightly elevated when compared to natural Finnish waters and metal concentrations in lake sediments show an increasing trend with time, both indicating long term leaching of metals from the waste deposits. All other metal concentration measurements revealed no elevated concentrations. In conclusion, we may state that the site is not a big if any threat to the environment and humans.