Emissions in Sudbury, Ontario

IDENTIFICATION: Release of sulfur dioxide into the air by industry in Sudbury, Ontario, Canada

After sulfur dioxide released during the processing of nickel and copper ore caused vast ecological devastation in the area in and around Sudbury, an environmental cleanup effort was undertaken that remains a model for the world at large.

The process of smelting involves heating sulfur-containing metal ores in air to convert the sulfide to the oxide form. In the process, the sulfur is removed in the form of sulfur dioxide. Without environmental controls, this gas goes into the atmosphere, where it reacts with water and oxygen to form sulfuric acid. This acid rain damages foliage, lakes, and structures, and causes difficulty for anyone with respiratory ailments. The unnatural acid levels (measured at a of less than 3 in some cases) may also lead to the of aluminum from soil into groundwater, which has negative impacts on roots and aquatic life in streams and lakes.

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In the late nineteenth and early twentieth centuries, nickel and copper sulfide ores were found in Sudbury, Ontario, Canada, just north of Lake Huron, and a metal mining and processing industry took root there. Extensive logging took place in the region as wood was needed for the growing settlements and for fuel for the smelter operations. Trees were unable to grow back in the deteriorating environment, and the denuded soil quickly eroded into waterways, adding to the devastation. At the same time, emissions from the smelting process included airborne metal particulates that deposited toxic levels of nickel and copper in the surrounding soil and water. By the early 1960’s Sudbury was known around the world for its acidified, lifeless lakes and its blackened, treeless landscape.

Late in the 1960’s the Canadian government began to respond to the growing worldwide environmental movement by ordering a reduction of sulfur dioxide and metal levels in the air around Sudbury. The ore-processing companies responded by constructing 380-meter (1,247-foot) “superstacks” that acted to reduce local air by spreading it over a larger area. During this period, the world was beginning to recognize the transboundary nature of pollution, particularly air pollution. Dangerously acidic conditions were found in a 50-kilometer (31-mile) radius of Sudbury and even farther in the direction of the prevailing winds.

Citizen outcry made it clear that improvements also had to occur inside the industrial plants. Among the changes implemented were the use of higher-grade ore, of sulfur gases to make and sell sulfuric acid, and treatment of gases to remove residual acid and particulates. Sudbury eventually became known for its of local lakes and soil through the application of basic materials (such as lime) and for replanting and nurturing young trees and other plants. Over twenty years, soil and water pH levels rose measurably, and plant and aquatic life slowly began to return to the area. In 1992, Sudbury received commendation at the Earth Summit in Brazil for its unprecedented success in environmental cleanup; the city’s efforts were noted as an example from which the rest of the world could learn. By the 2020s, Sudbury had a long-standing reputation as one of Canada’s most environmentally friendly cities.

Bibliography

Jacobson, Mark Z. Atmospheric Pollution: History, Science, and Regulation. New York: Cambridge University Press, 2002.

Keller, W., et al. “Recovery of Acidified Lakes: Lessons from Sudbury, Ontario, Canada.” In Acid Rain: Deposition to Recovery, edited by Peter Brimblecombe et al. New York: Springer, 2007.

Llana, Sara Miller. "The Sudbury Model: How One of the World’s Major Polluters Went Green." Christian Science Monitor, 24 Sept. 2020, www.csmonitor.com/Environment/2020/0924/The-Sudbury-model-How-one-of-the-world-s-major-polluters-went-green. Accessed 23 July 2024.