Articles | Volume 23, issue 3
https://doi.org/10.5194/bg-23-1103-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-23-1103-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
06 Feb 2026
Research article |
| 06 Feb 2026
| 06 Feb 2026
Reconstructing changes in nitrogen input to the Danube-influenced Black Sea Shelf during the Holocene
Andreas Neumann
CORRESPONDING AUTHOR
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Justus E. E. van Beusekom
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Alexander Bratek
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Center for Earth System Research and Sustainability, Institute of Geology, Universität Hamburg, Hamburg, Germany
Jana Friedrich
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Department of Nuclear Sciences and Applications, IAEA Marine Environment Laboratories, International Atomic Energy Agency, 98000 Monaco, Principality of Monaco
Jürgen Möbius
Center for Earth System Research and Sustainability, Institute of Geology, Universität Hamburg, Hamburg, Germany
Tina Sanders
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Hendrik Wolschke
Institute of Coastal Environmental Chemistry, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Kirstin Dähnke
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany
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Charlotte Haugk, Loeka L. Jongejans, Kai Mangelsdorf, Matthias Fuchs, Olga Ogneva, Juri Palmtag, Gesine Mollenhauer, Paul J. Mann, P. Paul Overduin, Guido Grosse, Tina Sanders, Robyn E. Tuerena, Lutz Schirrmeister, Sebastian Wetterich, Alexander Kizyakov, Cornelia Karger, and Jens Strauss
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Buried animal and plant remains (carbon) from the last ice age were freeze-locked in permafrost. At an extremely fast eroding permafrost cliff in the Lena Delta (Siberia), we found this formerly frozen carbon well preserved. Our results show that ongoing degradation releases substantial amounts of this carbon, making it available for future carbon emissions. This mobilisation at the studied cliff and also similarly eroding sites bear the potential to affect rivers and oceans negatively.
Gesa Schulz, Tina Sanders, Justus E. E. van Beusekom, Yoana G. Voynova, Andreas Schöl, and Kirstin Dähnke
Biogeosciences, 19, 2007–2024, https://doi.org/10.5194/bg-19-2007-2022, https://doi.org/10.5194/bg-19-2007-2022, 2022
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Estuaries can significantly alter nutrient loads before reaching coastal waters. Our study of the heavily managed Ems estuary (Northern Germany) reveals three zones of nitrogen turnover along the estuary with water-column denitrification in the most upstream hyper-turbid part, nitrate production in the middle reaches and mixing/nitrate uptake in the North Sea. Suspended particulate matter was the overarching control on nitrogen cycling in the hyper-turbid estuary.
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Short summary
The North-Western shelf of the Black Sea is substantially influenced by the discharge of nutrients from River Danube. We have sampled the sediment there and measured particulate carbon and nitrogen to reconstruct the variability of nitrogen sources to the NW shelf. Our results demonstrate that the balance of riverine nitrogen input and marine nitrogen fixation is sensitive to climate changes. Nitrogen from human activities is detectable in NW shelf sediment since the 12th century.
The North-Western shelf of the Black Sea is substantially influenced by the discharge of...
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