RAIN project. Annual report for 1987

Abstract

The RAIN project (Reversing Acidification in Norway) is an international research project aimed at investigating the effect on water and soil chemistry of changing acid deposition to whole catchment. The results from 1987 represent 4 years of treatment from Sogndal and 3 1/2 years at Risdalsheia. The original 5-year project period will be extended an additional 3 year through June 1991. Sulfate concentration have increased from about 20-25 µeg/l to 50-57 µeg/l at SOG2 and 35-45 µeg/l at SOG4. These levels are about 50% of the expectedsteady-state concentrations. Additions og HNO3 has caused only minor increases in nitrate in runoff. At Risdalsheia acid-exclution has resulted in lower concentrations of the strong acid anions NO3 (from 35 to 7 µeg/l) and SO4 (from 110 to 53 µeg/l) relative to both the roofed control catchment and open catchment. The input-output budgets indicate that the acid exclusion has reversed soil acidification at Risdalsheia. The effect of organic acvids on the pH of runoff has increased in importance as the acid-exclusion experiment has proceeded.