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Heavy Metal Content of Tundra Plant Species

It has long been known that certain plant species may be associated with soils that are characterized by high heavy metal levels. Some plants also preferentially concentrate certain heavy metals. The genus Astragalus, for instance, i s a good indicator for selenium and uranium in soil. Heavy metal uptake by plants has important implications to mineral prospecting and to animals harvesting the plants. Little detailed work on heavy metal uptake has been conducted in southern Canada and even less has been done in the subarctic and arctic areas. During the summer of 1975 a pilot study examining the uptake of copper, lead, zinc, cobalt, nickel, silver, cadmium, and uranium by arctic plants was carried out in the central District of Keewatin. The objective of this pilot project was to determine to what extent characteristic arctic species concentrated these metals in their tissues in areas of strongly contrasting geology and soil metal levels. Of the seven sites chosen for the study (Table 48.1) two were intended to be background areas, two were located on or near known uranium mineralization, one was located on a nickel-copper-rich gossan (only one species collected), one was located adjacent to zinclead mineralization with some copper, and one was located on a glacial indicator train about 2 km down-ice from zinc-lead mineralization.