Articles | Volume 19, issue 9
https://doi.org/10.5194/bg-19-2397-2022
© Author(s) 2022. 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-19-2397-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
06 May 2022
Research article |
| 06 May 2022
| 06 May 2022
A nitrate budget of the Bohai Sea based on an isotope mass balance model
Shichao Tian
CORRESPONDING AUTHOR
Institute for Geology, Universität Hamburg, 20146 Hamburg,
Germany
Birgit Gaye
Institute for Geology, Universität Hamburg, 20146 Hamburg,
Germany
Jianhui Tang
Yantai Institute of Coastal Zone Research, Chinese Academy of
Sciences, Yantai, China
Yongming Luo
Yantai Institute of Coastal Zone Research, Chinese Academy of
Sciences, Yantai, China
Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
Wenguo Li
Institute of Oceanography, Universität Hamburg, 20146 Hamburg,
Germany
Niko Lahajnar
Institute for Geology, Universität Hamburg, 20146 Hamburg,
Germany
Kirstin Dähnke
Institute for Coastal Research, Helmholtz-Zentrum Hereon, 21502 Geesthacht,
Germany
Tina Sanders
Institute for Coastal Research, Helmholtz-Zentrum Hereon, 21502 Geesthacht,
Germany
Tianqi Xiong
Institute of Marine Science and Technology, Shandong University,
Qingdao, China
Weidong Zhai
Institute of Marine Science and Technology, Shandong University,
Qingdao, China
Kay-Christian Emeis
Institute for Geology, Universität Hamburg, 20146 Hamburg,
Germany
Institute for Coastal Research, Helmholtz-Zentrum Hereon, 21502 Geesthacht,
Germany
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Total alkalinity (TA) regulates the oceanic storage capacity of atmospheric CO2. TA is also metabolically generated in estuaries and influences coastal carbon storage through its inflows. We used water samples and identified the Hamburg port area as the one with highest TA generation. Of the overall riverine TA load, 14 % is generated within the estuary. Using a biogeochemical model, we estimated potential effects on the coastal carbon storage under possible anthropogenic and climate changes.
Matthias Fuchs, Juri Palmtag, Bennet Juhls, Pier Paul Overduin, Guido Grosse, Ahmed Abdelwahab, Michael Bedington, Tina Sanders, Olga Ogneva, Irina V. Fedorova, Nikita S. Zimov, Paul J. Mann, and Jens Strauss
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We created digital, high-resolution bathymetry data sets for the Lena Delta and Kolyma Gulf regions in northeastern Siberia. Based on nautical charts, we digitized depth points and isobath lines, which serve as an input for a 50 m bathymetry model. The benefit of this data set is the accurate mapping of near-shore areas as well as the offshore continuation of the main deep river channels. This will improve the estimation of river outflow and the nutrient flux output into the coastal zone.
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
Biogeosciences, 19, 2079–2094, https://doi.org/10.5194/bg-19-2079-2022, https://doi.org/10.5194/bg-19-2079-2022, 2022
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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.
Birgit Gaye, Niko Lahajnar, Natalie Harms, Sophie Anna Luise Paul, Tim Rixen, and Kay-Christian Emeis
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Amino acids were analyzed in a large number of samples of particulate and dissolved organic matter from coastal regions and the open ocean. A statistical analysis produced two new biogeochemical indicators. An indicator of sinking particle and sediment degradation (SDI) traces the degradation of organic matter from the surface waters into the sediments. A second indicator shows the residence time of suspended matter in the ocean (RTI).
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To study the interaction of the westerlies and Indian summer monsoon (ISM) during the Holocene, we used paleoenvironmental reconstructions using a sediment core from the northeast Arabian Sea. We found a climatic transition period between 4.6 and 3 ka BP during which the ISM shifted southwards and the influence of Westerlies became prominent. Our data indicate a stronger influence of agriculture activities and enhanced soil erosion, adding to Bond event impact after this transition period.
Jiao Tang, Jiaqi Wang, Guangcai Zhong, Hongxing Jiang, Yangzhi Mo, Bolong Zhang, Xiaofei Geng, Yingjun Chen, Jianhui Tang, Congguo Tian, Surat Bualert, Jun Li, and Gan Zhang
Atmos. Chem. Phys., 21, 11337–11352, https://doi.org/10.5194/acp-21-11337-2021, https://doi.org/10.5194/acp-21-11337-2021, 2021
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This article provides a combined EEM–PARAFAC and statistical analysis method to explore how excitation–emission matrix (EEM) chromophores influence BrC light absorption in soluble organic matter. The application enables us to deduce that BrC absorption is mainly dependent on longer-emission-wavelength chromophores largely associated with biomass burning emissions. This method promotes the application of EEM spectroscopy and helps us understand the light absorption of BrC in the atmosphere.
Tim Rixen, Greg Cowie, Birgit Gaye, Joaquim Goes, Helga do Rosário Gomes, Raleigh R. Hood, Zouhair Lachkar, Henrike Schmidt, Joachim Segschneider, and Arvind Singh
Biogeosciences, 17, 6051–6080, https://doi.org/10.5194/bg-17-6051-2020, https://doi.org/10.5194/bg-17-6051-2020, 2020
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The northern Indian Ocean hosts an extensive oxygen minimum zone (OMZ), which intensified due to human-induced global changes. This includes the occurrence of anoxic events on the Indian shelf and affects benthic ecosystems and the pelagic ecosystem structure in the Arabian Sea. Consequences for biogeochemical cycles are unknown, which, in addition to the poor representation of mesoscale features, reduces the reliability of predictions of the future OMZ development in the northern Indian Ocean.
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Short summary
We constrain the nitrogen budget and in particular the internal sources and sinks of nitrate in the Bohai Sea by using a mass-based and dual stable isotope approach based on δ15N and δ18O of nitrate. Based on available mass fluxes and isotope data an updated nitrogen budget is proposed. Compared to previous estimates, it is more complete and includes the impact of the interior cycle (nitrification) on the nitrate pool. The main external nitrogen sources are rivers contributing 19.2 %–25.6 %.
We constrain the nitrogen budget and in particular the internal sources and sinks of nitrate in...
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