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European Marine Observation and Data Network (EMODnet)

Pollutant concentration: a guided tour to EMODnet Chemistry maps in the Map Viewer

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Map type “Measurements counts” for Cadmium contained in the «Heavy metals" variable group. You can use the «Layer animation» function to move from one layer to another and view the entire temporal extent of the data set.

Twenty-five new maps on pollutants have recently been made available in the EMODnet Map Viewer.

The products are divided into 3 categories that provide information on the distribution of sampling stations and concentration levels in space and time in all European seas and beyond for the parameters prioritised in the Marine Strategy Framework Directive.

The maps were produced for the following 12 pollutants in seawater, sediment, and biota: Tributyltin, Triphenyltin, Cadmium, Lead, Mercury, Nickel, Anthracene, Benzo(A)Pyrene, Fluoranthene, Naphthalene, DDT-DDE-DDD, and Hexachlorobenzene.

In the Map viewer Catalogue tab, select  EMODnet Chemistry and Contaminants categories. You will find 3 map types.
The first is called “Measurements counts” and contains the maps that show the number of available measurements per parameter and per matrix in the different stations for all available years and per year.

The second map type is called “Concentration values” and contains the maps that show for each parameter the concentration of the pollutant that has been measured per matrix. The concentration is expressed as median values of the last 6 available years. The medium values are calculated only using data included in EMODnet validated datasets and quality flagged as "good data". For water, only surface values are used (0-15 m), for sediment and biota data at all depths are used. In the Map Viewer the colour of the station indicates the percentile range in which the median value falls, as described in the legend in the menu on the left. For all parameters the units are: ug/l for water, and ug/kgr for biota, and sediment.

The third map type is called “Monitored matrices” and shows symbolised positions for each matrix for all available pollutant measurements in the validated EMODnet dataset.

If you click on the information button (“i”), you can Access to metadata and see the temporal and vertical extent of the data sets. Additionally, you can Download the data used to create the map.

At this point, switch from the Catalogue to the Layers tab to view, filter, or animate, enlarge and delete the layers using the specific buttons.

For types 1 and 3 in particular, you can use the "Layer animation" function, symbolised by the arrow, to follow the development over the years. For type 2 “Concentration values” you can filter the matrix you are interested in and retrieve the median value for each position by clicking on it.

EMODnet Chemistry main purpose is to make high quality datasets widely available and to promote the optimal use of these data. Most importantly, we are always ready to improve our products according to the needs of our users.


Alessandra Giorgetti, head of the National Oceanographic Data Centre at OGS, coordinating EMODnet Chemistry.


In this phase we have taken a step forward with the maps showing the spatial distribution of pollutant concentrations over the last 6 available years. I hope that this short tour will facilitate the understanding and use of these new maps for our stakeholders. We would encourage you to try out the EMODnet Map Viewer and send us your feedback by e-mail to


Anastasia (Sissy) Iona of Hellenic Centre for Marine Research (HCMR)

Finally, if you would like to explore the EMODnet Chemistry data collections in more detail, we recommend the EMODnet Chemistry webODV  Explorer and Extractor Service, which is operated by the Alfred Wegener Institute and EMODnet Chemistry. It allows users to create subsets, perform individual scientific analyses, create various graphs and download datasets in different formats for each of the numerous eutrophication and pollutant parameters contained in the EMODnet Chemistry data collections.