Rain,snow and lake water chemistry on and near the Precambrian Shield of Western Canada

Regional surveys of rain, snow and lake water chemistry have been conducted in several locations of western Canada which are considered sensitive to acidic deposition and are within several hundred kilometres of major Canadian point source emitters (664,000 tonne S0₂ in 1981). Snow and rain in the western Precambrian Shield is acidic with pH values generally ranging between 5.0 and 6.4. However, there is little evidence to suggest that the area is receiving significant amounts of acidic deposition. Total deposition of sulphate is approximately 2 kg ha^?1 between the months of April to October in 1983. Environmental impacts at present are minimal with most small lakes in the region having pH values near nuetrality and low concentrations of metals such as Al.