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Key Message

For total nitrogen, 13 open-sea assessment units were evaluated for the period 2011-2016, of which good status was achieved only in Kattegat and Great Belt (total nitrogen concentrations below a defined threshold value). In coastal water assessment units, the threshold values set for total nitrogen were commonly failed, though some Swedish, Finnish, Estonian and Polish coastal areas achieved the threshold values and good status (Key message figure 1).

 Total nitrogen 2018 _annual.png

Total nitrogen 2018 _summer.png

Total nitrogen 2018 _winter.png

Key message figure 1. Status assessment evaluation of the indicator 'Total nitrogen' - annual monitoring (top), summer (middle) and winter (bottom). The assessment is carried out using Scale 4 HELCOM assessment units (defined in the HELCOM Monitoring and Assessment Strategy Annex 4). Please note that for some sub-basins threshold values are still under discussion and that in coastal areas the assessment is based on annual data, summer data and winter data, as reported by HELCOM Contracting Parties, and these details are defined in Results table 2. See Results section below for details. Click here to access interactive maps at the HELCOM Map and Data Service: Total nitrogen.


The confidence in the presented total nitrogen status evaluation for the open sea areas is high in most of the assessed sub-basins. The data confidence was moderate in the Quark and low in Åland Sea. It should be noted that the confidence is only based on data availability, not the threshold confidence since the latter was not available for the indicator calculation.

The indicator is applicable in all coastal and open sea assessment units. The indicator period and method of calculation varies between open-sea and coastal areas, and thus the threshold- or assessment concentra­tions are not directly comparable between the open-sea and coast, nor between all coastal assessment units where nationally binding threshold values may have been set.

The indicator is applicable in the waters of all countries bordering the Baltic Sea, though not operational in all assessment units yet as for some open-sea areas threshold values still need to be agreed upon.

Relevance of the core indicator

Eutrophication is caused by excessive inputs of nutrients (nitrogen and phosphorus) resulting from various human activities. High concentrations of nutrients and their ratios form the preconditions for algal blooms, reduced water clarity and increased oxygen consumption. Long term nutrient data are key parameters for quantifying the effects of anthropogenic activities and evaluating the success of measures undertaken.


Policy relevance of the core indicator

  BSAP Segment and ObjectivesMSFD Descriptors and Criteria
Primary linkA Baltic Sea unaffected by eutrophication

D5 Human-induced eutrophication

- D5C1 Nutrient concentrations are not at levels that indicate adverse eutrophication effects

Secondary linkA favourable conservation status of Baltic Sea biodiversity

D1 Biological diversity of species and habitats

Theme: Pelagic habitats

-D1C6 The condition of the habitat type, including its biotic and abiotic structure and its functions, is not adversely affected due to anthropogenic pressures.

Theme: Benthic habitats

-D6C5 The extent of adverse effects from anthropo­genic pressures on the condition of the habitat type, including alteration to its biotic and abiotic structure and its functions, does not exceed a specified proportion of the natural extent of the benthic habitat type in the assessment area.

Other relevant legislation: Water Framework Directive, ecological status, QE4 ​ ​


Cite this indicator

HELCOM (2018). Total nitrogen. HELCOM core indicator report. Online. [Date Viewed], [Web link].

ISSN 2343-2543


Download full indicator report

Total nitrogen HELCOM core indicator 2018 (pdf)