RAIN project

The objective of the RAIN (Reversible Acidification in Norway) project was to predict the changes in biogeochemical processes and the time lag for improvement of the surface water chemistry, in response to a reduction in acid deposition.

The RAIN project was established 1983 and continued until it was replaced by the CLIMEX project in 1994. The RAIN project comprised two parallel large scale manipulated catchments in which acid deposition was artificially applied. The Sogndal site in western Norway received only minor acidic precipitation and was considered to be a pristine area which was sensitive to acid deposition. Four catchments were included in this study, two catchments served as untreated controls, one received H2SO4 and the final catchments received a 1:1 mixture of H2SO4 + HNO3. At Risdalsheia in southern Norway, ambient acid deposition was excluded by means of a 1,200 m2 roof, and clean precipitation was applied beneath the roof. Two untreated catchments were used as a control for this experiment.