Recovery of Acidified Lakes: Lessons From Sudbury, Ontario, Canada
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Over 7,000 lakes around Sudbury, Ontario, Canada were acidified by S deposition associated with emissions from the Sudbury metal smelters and more distant S sources. Air pollution controls have led to widespread changes in damaged Sudbury lakes, including increased pH and decreased concentrations of SO4, metals and base cations. While chemical improvements have often been substantial, many lakes are still acidified, although water quality recovery is continuing. Biological recovery has been observed in some lakes among various groups of organisms including fish, zooplankton, phytoplankton and zoobenthos. Generally, however, biological recovery is still at an early stage. Lakes around Sudbury are also showing that the recovery of acid-damaged lakes is closely linked to the effects of other major environmental stressors such as climate change, base cation depletion and UV-B irradiance. Future studies of the recovery of acid-damaged lakes around Sudbury, and in other regions, will need to consider the interactions of these and other stressors.
Keywordsacidification lakes recovery Sudbury sulphur stressors interaction
This paper is a contribution from the Aquatic Restoration Group of the Cooperative Freshwater Ecology Unit, a partnership between Laurentian University, the Ontario Ministry of the Environment, the Ontario Ministry of Natural Resources, CVRD Inco (formerly Inco Ltd.), Xstrata Nickel (formerly Falconbridge Ltd.), and Environment Canada.
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