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Metals in Soil and Vegetation in the Sudbury Area
(Survey 2000 and Additional Historic Data)
September 2001
Executive Summary

Environmental impacts of historical emissions of sulphur dioxide and heavy metals from the Inco Ltd. and Falconbridge Ltd. smelters in Sudbury have been well documented. Local and provincial governments, university researchers, and industry have done extensive monitoring, assessment, and reporting on the environmental impacts on terrestrial and aquatic ecosystems.

This report summarizes the previously unreported extensive soil and vegetation chemistry data from the Sudbury Regular Survey, the Sudbury Special Survey, and the Year 2000 Surface Soil Survey. These surveys were conducted in the Greater Sudbury area by the Ministry of the Environment during the period 1971 to 2000. Additional details regarding these surveys are provided in the report.

The study concludes that extensive sampling of soil and vegetation has illustrated elevated levels of heavy metals (specifically nickel, copper, cobalt and to a lesser extent, selenium) and arsenic are common in the Sudbury area. They are particularly elevated in the vicinity of the three historic smelting centres of Copper Cliff, Coniston, and Falconbridge, as well as, the historic roast yards. Apart from the roast yards [11], the highest concentrations in soil consistently occur in the top-most layer of the soil, usually 0-20 centimetres in depth. This indicates air emissions are the source of the contamination. Even though many samples have been taken several times over the last 30 years, it is not possible with this data set alone to confidently identify contaminant trends over time due to changes in laboratory procedures, the uncertainty that precisely the same site was sampled, and the natural variability of these contaminants in soil.

Soil levels are compared to the Ministry's Guideline For Use at Contaminated Sites in Ontario (1996). The MOE soil clean-up Guidelines have been developed to provide guidance for cleaning up contaminated soil. The Guidelines are not legislated regulations. Also, the Guidelines are not action levels, in that exceeding the level does not automatically mean that a clean-up must be conducted. The Guidelines were prepared to help industrial property owners decide how to clean-up contaminated soil when property is sold and/or the land-use changes. The value of the Guidelines to the Sudbury area report is to provide triggers that may suggest the need for additional investigation or assessment of soil contamination.

This study also concludes that additional sampling is required to achieve five objectives:

1. determine the soil metal and arsenic levels in residential communities adjacent to the smelting centers;
2. determine the soil metal and arsenic levels in industrial lands adjacent to residential communities;
3. contribute to the development of an ecological and human health risk assessment for the Sudbury area communities;
4. determine if the natural background levels of these contaminants are higher in the Sudbury basin due to the presence of base metal ore bodies; and
5. determine the true geographic extent of the metal and arsenic atmospheric deposition, based on the natural background levels.

Report Number SDB-045-3511-2001