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Recovery from acidification in Swedish forest streams
Jens Fölster1, Anders Wilander
1Department of Environmental Assessment, Swedish University of Environmental Sciences, Uppsala. jens.folster@ma.slu.se
Environmental Pollution (Barking, Essex : 1987)
|March 26, 2002
Summary
Sulphur deposition in Sweden has decreased, leading to signs of surface water recovery from acidification. Southern Sweden shows improving water chemistry, while northern regions show negligible effects from industrial acidification.
Area of Science:
- Environmental Chemistry
- Hydrology
- Ecology
Background:
- Sulphur deposition in Sweden has decreased significantly since 1970.
- Surface waters are showing initial signs of recovery from acidification.
- Acidification impacts are particularly noted in acid-sensitive soils of forested catchments.
Purpose of the Study:
- To investigate time trends in water chemistry between 1985 and 1998.
- To assess the recovery from acidification in Swedish streams.
- To correlate changes in water chemistry with sulphur deposition patterns.
Main Methods:
- Monitoring bulk deposition at nine catchments.
- Analyzing water chemistry trends in 13 streams over a 13-year period.
- Comparing stream water chemistry with deposition data and geographical gradients.
Main Results:
- Sulphate concentrations decreased in both stream water and deposition, with smaller trends in streams.
- A north-to-south gradient in sulphate trends was observed, linked to industrial influence.
- Five southern sites showed weak recovery signs: increased acid-neutralizing capacity and rising pH (0.01 units/year).
Conclusions:
- Observed decreases in acidity are interpreted as recovery from anthropogenic acidification.
- Changes in stream discharge, marine salts, or organic acids did not explain the observed recovery.
- In northern Sweden, water chemistry changes were attributed to natural variations, with negligible anthropogenic acidification effects.