The Scientific World Journal

The Scientific World Journal / 2001 / Article
Special Issue

Optimizing Nitrogen Management in Food and Energy Production and Environmental Protection: 2nd International Nitrogen Conference 2001

View this Special Issue

Research Article | Open Access

Volume 1 |Article ID 319865 |

R. Elmgren, U. Larsson, "Nitrogen and the Baltic Sea: Managing Nitrogen in Relation to Phosphorus", The Scientific World Journal, vol. 1, Article ID 319865, 7 pages, 2001.

Nitrogen and the Baltic Sea: Managing Nitrogen in Relation to Phosphorus

Academic Editor: Joe Wisniewski


The Baltic is a large, brackish sea (4 x 105 km2) extending from 54N to ~66N, with a fourfold larger drainage area (population 8 x 107). Surface salinity (2 to 8 PSU) and hence biodiversity is low. In the last century, annual nutrient loads increased to 106 metric tons N and 5 x104 ton P. Eutrophication is evident in the N-limited south, where cyanobacteria fix 2 to 4 x 105 ton N each summer, Secchi depths have been halved, and O2-deficient bottom areas have spread. Production remains low in the P-limited north. In nutrient-enriched coastal areas, phytoplankton blooms, toxic at times, and filamentous macroalgae reduce amenity values. Loads need to be reduced of both N, to reduce production, and P, to limit N-fixing cyanobacterial blooms. When large N-load reductions have been achieved locally, algal biomass has declined. So far, P loads have been reduced more than N loads. If this continues, a P-limited Baltic proper may result, very different from previous N-limited conditions. Reaching the management goal of halved anthropogenic N and P loads at minimum cost will require better understanding of biogeochemical nutrient cycles, economic evaluation of proposed measures, and improved stakeholder participation.

More related articles

 PDF Download Citation Citation
 Order printed copiesOrder

Related articles