RAIN PROJECT. Report for the years 1988, 1989 and 1990

Abstract

The Rain Project encompasses 7 years of catchment-scale experiments with acid addition at Sogndal and acid exclution at Risdalsheia. At Sogndal runoff contains increasingly higher concentrations of SO4 and NO3 these are compensated by increasing concentrations of base cations and decreasing alkalinity and pH. In 1989 the first indications of "nitrogen saturation" appeared. At Risdalsheiarunoff is now characterized by decreased concentrations of SO4 and NO3 these are compensated by decreased concentrations of base cations and increased alkalinity and pH. Runoff is highly acidic because of buffering by organic aids. The soils at Risdalsheia are accumulating base cations and are thus beginning recovery. The trends in runoff chemistry are predicted by MAGIC, a process-oriented model for soil and water acidification. At both sites additional years of treatment are necessary to evaluate the long-term dynamics of acidification and recovery.