​Key message

A significant reduction of nutrients input has been achieved for the whole Baltic Sea. In the last 3-year assessment (2012-2014) the average normalized input of nitrogen was reduced by 13% and phosphorus by 19% since the reference period (1997-2003) (Results figure 1). The maximum allowable input (MAI) of nitrogen in this period was fulfilled in the Kattegat, Danish Straits and Bothnian Sea (Key message figure 1 and Results tables 1a and 1b). Nitrogen inputs into Bothnian Bay and the Gulf of Riga are close to MAI but cannot be considered as fulfilled due to statistical uncertainty. MAI for phosphorus input is fulfilled in the Kattegat only. The inputs to the Danish Straits, Bothnian Sea and Bothnian Bay cannot be considered as fulfilled due to statistical uncertainty. Since the mid-1990s (Results table 2), total normalized nitrogen and phosphorus inputs to the Baltic Sea in 2014 were reduced by 22% and 24%, respectively.​​

Key message 1a.jpgKey message 1b.jpg

Key message figure 1: For each sub-basin and the whole Baltic Sea (BAS), 3 year average annual normalized total nitrogen and phosphorus inputs (tons per year) including statistical uncertainty in 2012-2014 are compared with the maximum allowable nutrient inputs (MAI t/y, shown as a blue line). Green colour indicates that inputs during 2012-2014 were lower than MAI, red colour when they were higher, while yellow indicates that when taking into account the statistical uncertainty of input data it is not possible to determine whether MAI was fulfilled. Note: the scales on the y-axes differ in the charts. Click image to enlarge.

Relevance of the core indicator

The input of nutrients is an indicator of eutrophication pressure on the marine ecosystem. In the Baltic Sea, the pressure is mainly driven by anthropogenic inputs of nitrogen and phosphorus to the sea.

The HELCOM nutrient reduction scheme defines maximum allowable inputs of nitrogen and phosphorous to Baltic Sea sub-basins, and inputs should not exceed these environmental targets in order to eventually obtain good environmental status in terms of eutrophication. This core indicator presents progress in the different Baltic Sea sub-basins towards reaching the MAI.

Policy relevance of the core indicator


Primary importance

Secondary importance

Segment and Objective

Eutrophication segment: nutrient reduction scheme

Has an influence on reaching objective Concentrations of nutrients close to natural levels

Maritime segment: Minimum air pollution from ships and minimum sewage pollution from ships

(Nutrient levels also affect biodiversity ecological objectives)

Descriptors and Criteria

Descriptor 5: Human-induced eutrophication is minimized, especially adverse effects thereof, such as losses in biodiversity, ecosystem degradation, harmful algae blooms and oxygen deficiency in bottom waters

Criterion 5.1. Nutrients concentration in the water column

Influence on achieving GES of the follow criteria:

  • 1.6.   Habitat condition

  • 5.2.   Direct effects of nutrient enrichment

  • 5.3.   Indirect effects of nutrient enrichment

Other relevant legislation: (e.g. WFD): EU Nitrates Directive; EU Urban Waste-Water Treatment Directive; Industrial Emissions Directive (IED), Water Framework Directive, WFD; the Gothenburg Protocol to Abate Acidification, Eutrophication and Ground-level Ozone under UNECE Convention on Long-range Transboundary Air pollution (CLRTAP); ); EU NEC Directive (2016/2284/EU); Water Code of Russian Federation; Federal Act on the internal maritime waters, territorial sea and contiguous zone of the Russian Federation; IMO designated the Baltic Sea as a "special area" for passenger ships under MARPOL (International Convention for the Prevention of Pollution from Ships) Annex IV (on sewage from ships); EC Directive 2000/59/EC on port reception facilities; NOx emission control area (NECA) in the Baltic and North seas designated by IMO. 


Cite this indicator

Lars M. Svendsen, Bo Gustafsson, Søren E. Larsen, Lars Sonesten, Seppo Knuuttila and Dmitry Frank-Kamenetsky (2017) Inputs of nitrogen and phosphorus to the Baltic Sea. HELCOM core indicator report. Online. [Date Viewed], [Web link].

ISSN 2343-2543

Download full indicator report

HOLAS II component - Core indicator report – web-based version July 2017 (pdf)