Occurrence of nickel in the Canadian environment

Abstract

Nickel is present in Canadian freshwater and terrestrial environments because of human activities including mining, smelting, refining, alloy processing, scrap metal reprocessing, other metal operations, fuel combustion, and waste incineration. Nickel can also enter the environment as a result of the natural weathering and leaching of rocks. Entry to the Canadian environment from anthropogenic activities results in measurable concentrations of nickel in various media to which organisms may be exposed. Although current anthropogenic rates of emission per tonne of nickel produced are less than 20 years ago, large quantities are still being emitted to the Canadian environment. Nickel is persistent in terrestrial and aquatic environments. While a large data base is available on concentrations of nickel in freshwater, sediment, soil, and terrestrial plants in Canada, relatively few data on concentrations in aquatic and terrestrial organisms are available. From data collected from 1981 to 1992, most unpolluted rivers and lakes in Canada contained between 0.1 and 10 μg nickel/L with the exception of the naturally elevated site of Smoking Hills, N.W.T. (which is at least three orders of magnitude greater), while industrial sites generally contained between 50 and 2000 μg nickel/L. Nickel levels in sediment collected from 1983 to 1992 from polluted sites such as the Welland River, some Sudbury lakes, and Hamilton and Toronto Harbours ranged between 20 and 5000 μg/g dry weight, while natural or background levels in the Niagara River, Lake Erie, Lake Superior, and Lake Huron were a full two orders of magnitude lower. With respect to drinking water sampled from 1984 to 1991, the trend has been a slight decrease in nickel levels with time but with a greater range emerging, which could be due to more sensitive detection equipment installed in 1986 (minima dropped from 1.0 μg/L to an order of magnitude lower). From data collected from 1984 to 1991, the more urbanization and industrialization associated with the city, the higher the means and medians of nickel levels in air. For example, Halifax, Montréal, Quebec, Windsor, Hamilton, and Toronto had greater air nickel levels than Ottawa, Winnipeg, and Edmonton. This trend was also confirmed with the subgroup of data collected from 1987 to 1990. Sudbury was by far the site with the greatest nickel concentrations (average 124 ng/m3). Furthermore, nickel accumulation in wildlife varied with species. For example, mice seemed to accumulate more nickel in their organs than did rats and other larger rodents, while beavers and minks, on average, accumulated more nickel in their livers than did birds in similar sites near Sudbury. Similar trends have been found in Canadian soil pore water, flora, and soil.Key words: nickel compounds, occurrence, Canadian environment.