Fate of legacy ammonium in the coastal Baltic Sea

Hellemann, Dana; Sun, Xiaole; Jilbert, Tom; Ehrnsten, Eva; Gustafsson, Bo; Harris, Lora; Humborg, Christoph; Müller-Karulis, Bärbel; Norkko, Alf

doi:10.5194/bg-23-7993-2026

Articles | Volume 23, issue 21

https://doi.org/10.5194/bg-23-7993-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-23-7993-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 23, issue 21

Research article

|

09 Nov 2026

Research article |

| 09 Nov 2026

Fate of legacy ammonium in the coastal Baltic Sea

Dana Hellemann, Xiaole Sun, Tom Jilbert, Eva Ehrnsten, Bo Gustafsson, Lora Harris, Christoph Humborg, Bärbel Müller-Karulis, and Alf Norkko

Data sets

The OC forcing and outputs of the reactive transport model for assessing the N legacy effect in coastal Baltic Sea Xiaole Sun and Dana Hellemann https://doi.org/10.5281/zenodo.22120110

Model code and software

The OC forcing and outputs of the reactive transport model for assessing the N legacy effect in coastal Baltic Sea Xiaole Sun and Dana Hellemann https://doi.org/10.5281/zenodo.22120110

Short summary

Using model-simulations and field data, we assess the effect of past eutrophication on present and future ammonium dynamics in coastal sediments of the Baltic Sea. Our results indicate a persistent but mild eutrophication legacy effect on sediment-water ammonium release, which is stronger driven by external organic matter loading. The results highlight that external organic matter loading needs to be reduced to also reduce ammonium loading to the coastal ecosystem and enable ecosystem recovery.