This dataset contains actual (non-normalized) riverine flow as well as actual atmospheric and waterborne inputs of nitrogen and phosphorus. In addition the dataset includes the normalized total nutrient inputs (atmospheric + waterborne) of nitrogen and phosphorus into the Baltic Sea. The data are used in the HELCOM core indicator on Inputs of nutrients (nitrogen and phosphorus) to the sub-basins 1995-2020 ( https://indicators.helcom.fi/indicator/inputs-of-nutrients/).

The river input data is based on reported riverine monitoring data as reported in HELCOM PLC data collection. Data on waterborne inputs, water flow and retention are reported by Contracting Parties to the PLC-Water database. The data are verified and quality assured using the PLC water database ( https://nest.su.se/helcom_plc/) verification tools and national expert quality assurance.

Atmospheric input data for all Baltic Sea sub-basins are available for the period 1990-2020. Atmospheric transport and deposition of nitrogen compounds are used for modelling atmospheric deposition to the Baltic Sea based on official emission data reported by EMEP Contracting Parties and expert estimates. Atmospheric input and source allocation budgets of nitrogen (oxidized, reduced and total) to the Baltic Sea basins and catchments were computed using the latest version of EMEP MSC-W model.

Input of nutrients (N=Nitrogen, P=Phospohus) units are tonnes per year per HELCOM PLC Subbasin. Area delineation of HELCOM PLC subbasins can be accessed from

https://maps.helcom.fi/website/mapservice/?datasetID=1456f8a5-72a2-4327-8894-31287086ebb5

Subbasin acronyms stand for:

BOB: Bothnian Bay

BOS: Bothnian Sea (including ARC = Archipelago Sea)

BAP: Baltic Proper

GUF: Gulf of Finalnd

GUR: Gulf og Riga

DS: Danish Straits (= WEB + SOU) (= Western Baltic + Sound)

KAT: Kattegat

BAS: The Baltic Sea