The core indicator evaluates average dissolved inorganic nitrogen (DIN) concentration in surface waters (0 – 10 m) during winter (December – February) for the assessment period 2011-2016.
Of the 17 open-sea assessment units none achieved good status (DIN concentration below defined threshold values, which reflect good conditions, Key message figure 1). The winter-time DIN is still at elevated levels in all 17 sub-basins. Decreases in DIN were recorded in the 1990s or the early 2000s, and since this decrease concentrations have generally remained at that level and not decreased further. Of all coastal waters where DIN was assessed, good eutrophication status was only found in Polish coastal waters and around the Swedish islands in Gotland Basin.
Key message figure 1. Status assessment result evaluation of the indicator 'DIN'. The assessment is carried out using Scale 4 HELCOM assessment units (defined in the HELCOM Monitoring and Assessment Strategy Annex 4). See Results section below for details. Click here to access
interactive maps at the HELCOM Map and Data Service: Dissolved inorganic nitrogen.
The confidence in the indicator DIN status evaluation was only high for the Kattegat, Arkona Basin, Bornholm Basin and Gulf of Finland assessment units. In all other open sea sub-basins the confidence was moderate or low (see below).
The indicator is applicable in the waters of all countries bordering the Baltic Sea. In coastal waters, total nitrogen may have been assessed instead of DIN (see Total Nitrogen indicator report) in line with the national assessments under the Water Framework Directive and the Russian Maritime Doctrine.
Eutrophication is caused by excessive inputs of nutrients (nitrogen and phosphorus) resulting from various human activities. High concentrations of nutrients and the ratios of these nutrients (e.g. N:P stoichiometric 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.
D5 Human-induced eutrophication
- D5C1 Nutrient concentrations are not at levels that indicate adverse eutrophication effects
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.
HELCOM (2018). Dissolved inorganic nitrogen (DIN). HELCOM core indicator report. Online. [Date Viewed], [Web link].
Dissolved inorganic nitrogen DIN HELCOM core indicator 2018 (pdf)