Assessment of aluminium mobilization and pathways in the Birkenes catchment, southern Norway

Abstract In spite of considerable research efforts the detailed mechanisms involved in acidification, and in particular those controlling aluminium concentrations in water, have not been satisfactorily established. In this paper, earlier work on acidification carried out in the Birkenes catchment in southern Norway is first reviewed. Temporal variations in acidity and aluminium concentrations in stream water are related to variations in ionic loadings. Addition of sodium bromide to two small soil plots in Birkenes resulted in high concentrations of H + in the organic horizon and of Al 3+ in the eluvial horizon. The experiment supports the hypothesis presented earlier that water pathways are of great significance in determining stream water chemistry. Suggestions for the improvement of existing models for calculating stream water aluminium concentrations are given.