Eutrophication-acidity and contaminants: the new data collections submitted to ICES for use by the EEA

EMODnet has offered European scale data collections for eutrophication– acidity and contaminants for some years, updated on an annual basis with the latest data available. The annual update has just been completed by EMODnet Chemistry Coordinator OGS, Italy, in collaboration with its Regional Coordinators (RCs), then prepared for online viewing by EMODnet partner Ifremer, France and submitted to EMODnet partner ICES for the further review and submission of the data collections to the European Environment Agency (EEA). The data collections will soon be published on the EMODnet web portal in the EMODnet Chemistry Data and Products section and in the Products Catalogue.

In this news article, we go behind the scenes of this data product and talk to Maria Eugenia Molina Jack, marine data manager at the OGS, Italy, to find out more.

Can you tell us about these new ocean chemistry data collections?

Molina Jack - “In the coming days, EMODnet Chemistry will publish six data collections for contaminants and six for eutrophication–acidity, specifically for the Arctic Ocean, Baltic Sea, Greater North Sea, North-East Atlantic, Mediterranean Sea and Black Sea. The available data types are organised in vertical profiles and time series. Vertical profiles are data collected at approximately the same time and location for several consecutive vertical depths, while time series are collected at the same location and depth but repeated in time.

Can you explain the first steps that led to their production?

Molina Jack - “The harvest of research and monitoring data was finalised in December 2024. This phase of the process is coordinated by MARIS, EMODnet Chemistry technical coordinator. The data, which cover 13 groups of chemical variables within all European sea regions, are initially gathered in the SeaDataNet Data Discovery and Access Service and then an automated Robot Harvester, properly configured with predefined criteria of geographical and temporal coverage and parameters, is used to retrieve specific datasets from the distributed network of data centres to provide datasets for each marine region. The regional data are delivered to six RCs from the following organisations: AU-DCE (Greater North Sea), HCMR (Mediterranean Sea, including Marmara Sea), IFREMER (NE Atlantic Ocean), NIMRD (Black Sea), SMHI (Baltic Sea), IMR (Arctic Ocean). The RCs strive to aggregate, harmonise and quality control metadata and datasets from dozens of data centres, which in turn collect data from hundreds of research and monitoring institutions. The impressive amount of data, covering a wide range of parameters, are collected in different matrices, using a variety of platforms, devices and protocols, and analysed using many different tools and methodologies.” 

We also met Megan Anne French, another marine data manager at OGS. 

Can you tell us about the role of the RCs in the data collection process? Why was this time even more challenging for them?

French - “The RCs update the data collections annually, making any improvements to the quality and quantity of the associated information. RCs help to verify the adequacy of the vocabularies used and the standards and formats. In this way, they also play a key role in developing or enhancing tools and services for the creation of data collections and related products. The creation of these data collections was an even greater challenge than the previous ones, as EMODnet Chemistry has carried out a complete revision of the data/metadata, which takes place approximately every four years. This makes it possible to improve the quality of the whole data collections, based on feedback e.g., errors reported by the data providers themselves, RCs or OGS. This creates an updated data collection with the metadata enriched.” 

Can you briefly describe the steps taken to prepare the collections?

French - “The process is based on the ‘quality control loop’ involving data originators, who provide ‘source data’, data managers, who are responsible for ‘standardisation’, and RCs, who are responsible for ‘validation’. The steps are different for the two types of data collections. In the case of eutrophication, the first step is to aggregate the parameters. Parameter aggregation concerns unit conversions and harmonisation of parameter coding and meaning. This is done at the regional level using special vocabulary that serves to combine different terms associated with the same parameter but measured with different instruments or originally expressed with different units of measurement that get harmonised, into a single aggregated term. Data validation by the RCs is the following step. This includes a series of checks that concern the verification of temporal and spatial data distribution, the comparison of cross-parameters, the calculation of derived variables, the comparison with ‘broad ranges’ derived from the literature and with climatologies available from historical data. For contaminant data, chemicals relevant to the Marine Strategy Framework Directive (MSFD) have been selected and the process leading to the compilation of the data collections includes the harmonisation of the naming of units and parameters as well as the validation of the metadata. Due to the lack of scientific guidance at regional level, contaminant data are not checked against ‘broad ranges’. Data quality control involves checking the file format and removing data that are clearly unreliable.”

Marina Lipizer, researcher and data manager at the OGS, adds: “It is worth noting that the data are never removed or modified, but they are flagged by the originators of the data and checked by the RCs according to commonly agreed QC guidelines. For this purpose, the list of SeaDataNet Quality Flags is adopted. If the RCs make changes to the quality flags, these are communicated to the data originators so that they can validate the change request and revise and correct the original datasets”.

What does the EEA use these data for? 

Lipizer. “Since 2017, the data collections, including data from the EMODnet Chemistry network, including partner ICES, have provided a comprehensive European data source for EEA marine indicators on contaminants (biota) and eutrophication (chlorophyll and nutrients), as well as a pipeline on oxygen saturation. The data also feeds into the ‘European environment – state and outlook’ report, which is published by the EEA every five years.”

All data entering EMODnet Chemistry are managed according to standard protocols developed within the framework of the consolidated European marine data infrastructure SeaDataNet which includes many EMODnet partners.

To learn more about the methodology agreed with the international community for the aggregation, harmonisation and validation of data and/or metadata, read the guidelines

• EMODnet Chemistry Regional Sea eutrophication data collection and Quality Control loop 

• Quality Control steps for EMODnet Chemistry Contaminant aggregated datasets.

The published data collections only contain unrestricted data, which make up the majority, while the remaining percentage is accessible after negotiations with the data owners within the framework of the data policy.

You can find the most important figures in the data collections at a glance in the charts below.

Figure 1. Eutro–acidity2025 - The most important figures on the 2025 data collections for eutrophication–acidity. ©EMODnet Chemistry

Figure 2. Contaminants data 2025 - The most important figures on the 2025 data collections for contaminants. ©EMODnet Chemistry

For details, you can take a look at the table below.