Afforestation, seasalt episodes and acidification--a paired catchment study in western Norway.
As acid deposition has declined during the past 15-20 years in western Norway, afforestation and episodic seasalt deposition have become factors of increasing importance in explaining the mobilization of toxic aluminum (Aln+) to rivers and lakes. We conducted a paired catchment at four sites in western Norway across a gradient in acid deposition to evaluate the importance of afforestation and seasalt episodes. Streamwater was sampled intensively before, during and after seasalt episodes over a three-year period. A seasalt episode in January 2003 caused considerable impact on the streamwater chemistry. pH dropped and concentrations of Aln+ increased due to cation exchange of Na+ ions for H+ and Aln+ in the soil. The response was larger in streams draining the catchments which receive high acid deposition and in those afforested with spruce as compared with adjacent catchments in native birch. The results indicate that acid pulses induced by episodic inputs of seasalts are exacerbated by land use change from native birch to planted spruce.
Larssen
Thorjørn
T
Norwegian Institute for Water Research, P.O. Box 173, Kjelsaas, 0411 Oslo, Norway. thorjorn.larssen@niva.no
Holme
Jorun
J
D015258:Acid Rain; D000535:Aluminum / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D016468:Forestry; D005618:Fresh Water / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009664:Norway; D045483:Rivers; D012965:Sodium Chloride / Q000032:analysis*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis
D015258:Acid Rain; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D000535:Aluminum