Soil Acidification

Soil acidification happens when acid-forming compounds, such as sulphur and nitrogen, exceed the buffering capacity of the soil to which they are added. Resulting changes to the soil's chemical and physical properties can have negative impacts on vegetative growth and soil health.

Background

Most acid deposition comes from sulphur dioxide and nitrogen oxides in the atmosphere, released by industrial, commercial and residential activities. These compounds react in the atmosphere to form acid rain. There is no simple solution to remedy the impact of large-scale acidification.

Alberta first identified sour gas processing and other industrial facilities as sources of acidifying emissions in the 1960s and 1970s. Many studies were undertaken, the benchmark being The Present and Potential Effects of Acidic and Acidifying Air Pollutants on Alberta's Environment released in 1988. Alberta Environment (now Alberta Environment and Parks) also began a long-term soil monitoring study in the 1980s to determine how soil chemistry changed with long-term exposure to acidic emissions.

A significant reduction in acidifying emissions in the 1980s and 1990s was offset by increased development of oil sands operations and electric power generation. Natural gas processing now accounts for less than 50 per cent of sulphur dioxide emissions.

Current status

The focus is now globally on identifying sensitive land and water areas. Long-range transport of acidifying emissions can result in impacts on sensitive systems far from the emission source. Maps showing the sensitivity of Alberta soils to acid input and the potential of soil and geology to reduce acidity of incoming acidic deposition have been prepared to assist in modeling exercises.

Alberta soils are generally rich in calcium and magnesium that buffer acidifying emissions. Soils located on the Canadian Shield are more susceptible to the effects of these emissions.

Alberta Environment and Parks (AEP); the Clean Air Strategic Alliance (CASA); airshed groups and industry organizations representing oil and gas, coal, power generation; and other industries are all involved in the acidifying emissions issue.

Alberta is a signatory to the Canada-Wide Acid Rain Strategy for Post-2000. This strategy focuses on sulphur dioxide emission reductions in Canada and the U.S., as well as continuing research and monitoring activities. In 1999, Alberta Environment (now AEP) implemented the Acid Deposition Management Framework for long-term management of acid deposition.

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Updated: May 10, 2017