The largely recognized BALTSEM model (the BAltic sea Long-Term large Scale Eutrophication Model) is used to assess nutrient/carbon cycles and eutrophication in the Baltic Sea. Now this model has been expanded to also include organic contaminant environmental transport and fate – BALTSEM-POP. Organic contaminants are emitted within the Baltic Sea catchment, or transported to this region via air masses from far distances. Fate, which means where the contaminants end up in the ecosystem, is influenced by a wide range of environmental factors, which are all included in the BALTSEM-POP model.

– The novelty of the BALTSEM-POP model is that it dynamically calculates several key factors that can influence the amount and composition of contaminants ending up in the Baltic Sea, says researcher Emma Undeman at the Baltic Nest Institute, Baltic Sea Centre and Department of Applied Environmental Science at Stockholm University. This means that the model allows for short- and long-term variation in important factors such as carbon cycling, water flows, wind speed, water and air temperature.

– It is an important feature of the BALTSEM-POP model that we are able to include variation in these factors since they are affected by climate change and eutrophication. Moreover, this model can predict how contaminant concentrations will vary with the water depth for the entire Baltic Sea, says Emma Undeman.

The researchers at Stockholm University have evaluated the accuracy of their new BALTSEM-POP model by comparing simulated concentrations of the environmental toxins polychlorinated biphenyls (PCBs), dioxins and furans (PCDD/Fs) and hexachlorobenzene (HCB) in water, suspended particulate organic matter and sediment with values from actual field observations.

The BALTSEM-POP model performs with high accuracy for concentrations of the majority of these organic contaminants in water and sediment, while it was found to be more difficult to predict the contaminant concentrations in particulate organic matter.

– The general good performance of the new model shows that it can be an important tool for predicting future contaminant concentrations in different matrices in the Baltic Sea in response to variations in nutrient input and climatic conditions, says Emma Undeman.

Link to the article in Science of The Total Environment:

For further information
Emma Undeman, Researcher, Baltic Nest Institute, Baltic Sea Centre and Department of Applied Environmental Science, Stockholm University, Telephone +46 (0)8 674 75 17,

Erik Gustafsson, Researcher, Baltic Nest Institute, Baltic Sea Centre, Stockholm University, Telephone +46 (0)8 674 71 25, Cell +46 (0)73 461 25 34,

Bo Gustafsson, Director of Baltic Nest Institute, Baltic Sea Centre, Stockholm University, Cell +46 (0) 73 707 86 03,

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Author: Marie Löf