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While there was little decline in emissions of nitrogen oxides between 1985 and 2000 in either country, nitrogen oxides are predicted to decline approximately 17 per cent in Canada and 47 per cent in the United States by 2020.
Although it is expected that 2010 emissions targets will be achieved, research indicates that many lakes and forests will continue to sustain damage from acid rain. Current reduction targets are not sufficient to prevent damage from acid rain in eastern Canada.
Acid Rain in Canada
The results of the 2004 Canadian Acid Deposition Science Assessment confirm that although levels of acid rain have declined in eastern Canada over the last several decades, approximately 21 per cent of eastern Canada continues to receive levels of acid rain in excess of what the region can handle and 75 per cent of eastern Canada is at risk of damage. Despite widespread misconceptions that the issue is solved, new research indicates that the problem could linger for another 60 years or more.
Acid rain is a particular problem in eastern Canada because many of the water and soil systems in this region lack natural alkalinity – such as a lime base – and therefore do not have a natural capacity to neutralize acid. Provinces that are part of the Canadian Precambrian Shield, like Ontario, Quebec, New Brunswick and Nova Scotia, are hardest hit because their water and soil systems cannot fight the damaging consequences of acid rain. In fact, more than half of Canada consists of granite areas that have little capacity to neutralize the effects of acid rain. If the water and soil systems were more alkaline – as in parts of western Canada and southern Ontario – they could neutralize acid rain naturally.
Historically, the eastern part of Canada and the United States also suffer from higher levels of industrialization. However, large increases in emissions of sulphur and nitrogen oxides from oil sands operations in northern Alberta are raising concerns that the problem of acid rain may expand west.
Impacts of Acid Rain
Acid rain has negative impacts on lakes, rivers, soils, forests, wildlife, biodiversity, buildings, and human health.
Lakes and rivers that have been acidified cannot support the same variety of life as healthy water sources. Many aquatic species such as algae, fish, water birds and other freshwater life find acidified waters toxic. Since many lakes and streams continue to be acidified by acid rain, the biodiversity of large regions of eastern Canada is reduced. For example, researchers predict that Atlantic salmon populations in rivers of the southern upland region of Nova Scotia will become extinct if adult death rates remain high and acid rain continues.
Acid rain is removing essential nutrients, such as calcium, from soils which is negatively affecting the health and growth of trees. At current levels, it is estimated that over half-a-million cubic metres of wood is being lost from forests in Atlantic Canada each year due to loss of soil nutrients.
The corrosive impacts of acid rain can damage property, particularly older stone buildings and electrical transmission towers. For electrical towers, acid rain can reduce the life expectancy by 50 per cent and greatly increase repair frequency with an annual cost of thousands of dollars per tower.
Our health is also affected. Recent studies found links between incidence of acid rain and respiratory symptoms, impaired lung function, hospital admissions and premature death.
Canada has been successful in reducing acid-causing emissions to date. However, acid rain is still a problem. Researchers estimate that a further 75 per cent reduction in sulphur dioxide emissions will be required from Canada and the United States, beyond those agreed to for 2010, to protect the health of Canadians as well as eastern Canadian ecosystems from damage by acid rain.
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