Nitrogen and phosphorus inputs

Fig 1_nitrogen.jpgFig 1_phosphorus.jpg 

Figure 1.  For each sub-basin and the Baltic Sea as a whole (BAS), average annual total nitrogen (top) and phosphorus (bottom) inputs in 2010-2012 are compared with the maximum allowable nutrient inputs (MAI, shown as a blue line). The average annual inputs in 2010-2012 were calculated using normalized annual inputs. Green colour indicates that inputs during 2010-2012 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.

Key message

The maximum allowable inputs (MAI) of nitrogen and phosphorus were fulfilled in Kattegat, the Danish Straits and Bothnian Sea during 2010-2012 (Figures 1). For Bothnian Bay nitrogen inputs are close to MAI but cannot be regarded as fulfilled with statistical certainty. Total normalized nitrogen and phosphorus inputs have decreased with 18% and 23%, respectively, to the Baltic Sea since the mid-1990s (Table 3).

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 importanceSecondary 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); 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; Application on the Baltic Sea NOx emission control area (NECA) has not yet been submitted to IMO.


Lars M. Svendsen1, Minna Pyhälä2, Bo Gustafsson3, Lars Sonesten4 and Seppo Knuuttila5

With support from the HELCOM Reduction Scheme Core Drafting Group (RedCore DG)

1 DCE - Danish Centre for Environment and Energy, Aarhus University

2 HELCOM Secretariat

3 Baltic Nest Institute, Sweden

4 Swedish University of Agricultural Sciences, SLU

5 Finnish Environment Institute, SYKE


How to cite this indicator

Svendsen, L.M., Pyhälä, M., Gustafsson, B.,  Sonesten, L. Knuuttila, S. 2015. Inputs of nitrogen and phosphorus to the Baltic Sea. HELCOM core indicator report. Online. [Date Viewed], [Web link].