Sulphate and base cation concentrations and export in streams from unmanaged forested catchments in Finland

• Published in: Forest ecology and management 2004-06, Vol.195 (1), p.115-128
• Main Authors: Finér, Leena, Kortelainen, Pirkko, Mattsson, Tuija, Ahtiainen, Marketta, Kubin, Eero, Sallantaus, Tapani
• Format: Article
• Language: English
• Subjects: Atmospheric deposition; Discharge; Forest; Freshwater; Leaching; Nutrient; Stream water quality
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2004.02.040

Sulphate and base cation (Ca 2+, Mg 2+, K +, Na +) concentrations and export, and their relationships with catchment characteristics, were studied in stream water flowing out of unmanaged forested catchments in Finland. Data were collected during 1997–1999 from 21 first-order catchments, and they were combined with a corresponding data from another 19 catchments monitored in other studies during periods ranging from 1978 to 1999. The results showed that the concentrations of SO 4 2− ,K + and Na decreased in streams on moving from the south to the north, and that the decrease was most pronounced for SO 4 2. In the export of elements from the catchments, a similar regional pattern was observed for SO 4 2− only. The south–north decrease in stream water concentrations was mainly explained by the level of atmospheric deposition of SO 4 2−. The average forest site type on the whole catchment area, which describes the productivity of the sites had a significant positive correlation with the concentrations and export of SO 4 2− and Ca 2+, Mg 2+, K + and Na +, probably reflecting higher base cation concentrations in the soil on fertile sites. There were exceptionally high concentrations and exports of sulphate and base cations in some of the streams compared to the general pattern for the whole country, probably reflecting special bedrock or soil types or the vicinity to local deposition sources.