Nutrient loads to the Baltic Sea
1996 (English)Doctoral thesis, comprehensive summary (Other academic)
Nutrient enrichment is generally regarded as the greatest threat to the ecosystems of the Baltic Sea. This thesis demonstrates that the loads of nitrogen and phosphorus in the rivers in the Baltic Sea drainage basin are larger than previously assumed and by far exceed the size of the loads that reach the sea by way of other pathways, i.e. atmospheric deposition, nitrogen fixation, and direct discharges from urban areas and industries on the coast. In addition, examination of time series of nutrient concentrations and runoff for more than 100 rivers showed that, despite considerable changes in land-based activities in several parts of the drainage basin, the riverine loads of nutrients were fairly constant during the time period 1970-1993. Case studies of riverine loads of nitrogen in Latvia and Sweden confirmed that the terrestrial and aquatic ecosystems that control the riverine export of nutrients have a substantial inertia. In Latvia, the dramatic reduction in the application of fertilisers during the early 1990s has not yet led to a decrease in riverine nutrient loads. Moreover, results obtained in Sweden do not provide convincing evidence that nitrogen saturation of forest soils has caused a large-scale increase in the export of nitrogen from forested river basins. The most pronounced examples of upward nitrogen trends in Sweden were all found at sampling sites downstream of lakes and were probably caused by lowered nitrogen retention due to decreased emissions of organic matter or phosphorus. To facilitate detection and interpretation of temporal trends in riverine loads of nutrients, a new semiparametric flow-normalisation method was developed. In addition, a new statistical technique for source apportionment of riverine loads of nutrients was developed and applied to data from a Swedish river basin.
Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 1996. , 78 p.
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 146
Social Sciences Interdisciplinary
IdentifiersURN: urn:nbn:se:liu:diva-35379Local ID: 26425ISBN: 91-7871-829-5OAI: oai:DiVA.org:liu-35379DiVA: diva2:256227
1996-09-27, Sal C 1, Hus C, Universitetsområdet Valla, Linköping, 10:15 (Swedish)
Papers, included in the Ph.D. thesis, are not registered and included in the posts from 1999 and backwards.2009-10-102009-10-102012-07-10Bibliographically approved