The purpose of this study is to use the snowpack of the Saskatchewan portion of the Precambrian Shield as a passive collector of atmospheric total deposition. Although the focus is on the anions of sulphate and nitrate, the hydrogen ion and various metals are also considered.
Twenty-six small lakes on the Precambrian Shield area of northern Saskatchewan were used as sites. The lakes were all approximately 1 square km in area and serviced by aircraft. The study was conducted in late March 1982 and 1983 just before the major snowmelt period.
Concentrations of sulphate ranged from 0.26 to 7.3 mg 1−1. The concentrations were typical of large areas in northern Saskatchewan with sharp transitions in composition occurring as the treeline boundary was encountered. Typical sulphate deposition was approximately 30 mg m−2 in the Precambrian areas and 150 mg m−2 in the other areas. The distribution of conductivity in the snow cores ranged from 6 to 13 μS cm−1. Most of the snow on the Precambrian Shield areas can be described as acidic, with pH values of the meltwater being below 5.6.
Metals such as Ca, Mn, Mg, Zn and As were measured across the region. The metals Ca and Mg show a direct correlation with high sulphate levels south of the treeline. Metals such as Zn and As show anthropogenic influence particularly within 100 km of industrial sources. Large areas of the study region show uniform and low deposition to the snowpack. It is suggested that natural atmospheric processes are dominating deposition in this area of Canada.