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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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.
Gesa Schulz, Kirstin Dähnke, Tina Sanders, Jan Penopp, Hermann W. Bange, Rena Czeschel, and Birgit Gaye
EGUsphere, https://doi.org/10.5194/egusphere-2025-1660, https://doi.org/10.5194/egusphere-2025-1660, 2025
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Oxygen minimum zones (OMZs) are low-oxygen ocean areas that deplete nitrogen, a key marine nutrient. Understanding nitrogen cycling in OMZs is crucial for the global nitrogen cycle. This study examined nitrogen cycling in the OMZ of the Bay of Bengal and East Equatorial Indian Ocean, revealing limited mixing between both regions. Surface phytoplankton consumes nitrate, while deeper nitrification recycles nitrogen. In the BoB’s OMZ (100–300 m), nitrogen loss likely occurs via anammox.
Anjaly Govindankutty Menon, Aaron L. Bieler, Hanna Firrincieli, Rachel Alcorn, Niko Lahajnar, Catherine V. Davis, Ralf Schiebel, Dirk Nürnberg, Gerhard Schmiedl, and Nicolaas Glock
EGUsphere, https://doi.org/10.5194/egusphere-2025-1182, https://doi.org/10.5194/egusphere-2025-1182, 2025
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The pore density (number of pores per unit area) of unicellular eukaryotes is used to reconstruct past bottom-water nitrate at the Sea of Okhotsk, the Gulf of California, the Mexican Margin and the Gulf of Guayaquil. The reconstructed bottom-water nitrate at the Sea of Okhotsk, the Gulf of California and the Gulf of Guayaquil are influenced by the intermediate water masses, while the nitrate at the Mexican Margin is related to the deglacial NO3− variability in the Pacific Deep Water.
Jan Maier, Nicole Burdanowitz, Gerhard Schmiedl, and Birgit Gaye
Clim. Past, 21, 279–297, https://doi.org/10.5194/cp-21-279-2025, https://doi.org/10.5194/cp-21-279-2025, 2025
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We reconstruct sea surface temperatures (SSTs) of the past 43 kyr in the Gulf of Oman. We find SST variations of up to 7 °C with lower SSTs during Heinrich events (HEs), especially HE4, and higher SSTs during Dansgaard–Oeschger events. Our record shows no profound cooling during the Last Glacial Maximum but abrupt variations during the Holocene. We surmise that SST variations are influenced by the southwest (northeast) monsoon during warmer (colder) periods.
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The Siberian Arctic is warming fast: permafrost is thawing, river chemistry is changing, and coastal ecosystems are affected. We aimed to understand changes in the Lena River, a major Arctic river flowing to the Arctic Ocean, by collecting 4.5 years of detailed water data, including temperature and carbon and nutrient contents. This dataset records current conditions and helps us to detect future changes. Explore it at https://doi.org/10.1594/PANGAEA.913197 and https://lena-monitoring.awi.de/.
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
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Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Medhavi Pandey, Haimanti Biswas, Daniel Birgel, Nicole Burdanowitz, and Birgit Gaye
Biogeosciences, 21, 4681–4698, https://doi.org/10.5194/bg-21-4681-2024, https://doi.org/10.5194/bg-21-4681-2024, 2024
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We analysed sea surface temperature (SST) proxy and plankton biomarkers in sediments that accumulate sinking material signatures from surface waters in the central Arabian Sea (21°–11° N, 64° E), a tropical basin impacted by monsoons. We saw a north–south SST gradient, and the biological proxies showed more organic matter from larger algae in the north. Smaller algae and zooplankton were more numerous in the south. These trends were related to ocean–atmospheric processes and oxygen availability.
Nicole Burdanowitz, Gerhard Schmiedl, Birgit Gaye, Philipp M. Munz, and Hartmut Schulz
Biogeosciences, 21, 1477–1499, https://doi.org/10.5194/bg-21-1477-2024, https://doi.org/10.5194/bg-21-1477-2024, 2024
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We analyse benthic foraminifera, nitrogen isotopes and lipids in a sediment core from the Gulf of Oman to investigate how the oxygen minimum zone (OMZ) and bottom water (BW) oxygenation have reacted to climatic changes since 43 ka. The OMZ and BW deoxygenation was strong during the Holocene, but the OMZ was well ventilated during the LGM period. We found an unstable mode of oscillating oxygenation states, from moderately oxygenated in cold stadials to deoxygenated in warm interstadials in MIS 3.
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This is the first report of long-term atmospheric PAH monitoring around the Bohai Sea. The results showed that the concentrations of PAHs in the atmosphere around the Bohai Sea decreased from June 2014 to May 2019, especially the concentrations of highly toxic PAHs. This indicates that the contributions from PAH sources changed to a certain extent in different areas, and it also led to reductions in the related health risk and medical costs following pollution prevention and control.
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Arctic warming accelerates permafrost thaw and release of terrestrial organic matter (OM) via rivers to the Arctic Ocean. We compared particulate organic carbon (POC), total suspended matter, and C isotopes (δ13C and Δ14C of POC) in the Lena delta and Lena River along a ~1600 km transect. We show that the Lena delta, as an interface between the Lena River and the Arctic Ocean, plays a crucial role in determining the qualitative and quantitative composition of OM discharged into the Arctic Ocean.
Jiao Tang, Jun Li, Shizhen Zhao, Guangcai Zhong, Yangzhi Mo, Hongxing Jiang, Bin Jiang, Yingjun Chen, Jianhui Tang, Chongguo Tian, Zheng Zong, Jabir Hussain Syed, Jianzhong Song, and Gan Zhang
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This study provides a comprehensive molecular identification of atmospheric common fluorescent components and deciphers their related formation pathways. The fluorescent components varied in molecular composition, and a dominant oxidation pathway for the formation of humic-like fluorescent components was suggested, notwithstanding their different precursor types. Our findings are expected to be helpful to further studies using the EEM-PARAFAC as a tool to study atmospheric BrC.
Kirstin Dähnke, Tina Sanders, Yoana Voynova, and Scott D. Wankel
Biogeosciences, 19, 5879–5891, https://doi.org/10.5194/bg-19-5879-2022, https://doi.org/10.5194/bg-19-5879-2022, 2022
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Nitrogen is an important macronutrient that fuels algal production in rivers and coastal regions. We investigated the production and removal of nitrogen-bearing compounds in the freshwater section of the tidal Elbe Estuary and found that particles in the water column are key for the production and removal of water column nitrate. Using a stable isotope approach, we pinpointed regions where additional removal of nitrate or input from sediments plays an important role in estuarine biogeochemistry.
Mona Norbisrath, Johannes Pätsch, Kirstin Dähnke, Tina Sanders, Gesa Schulz, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 19, 5151–5165, https://doi.org/10.5194/bg-19-5151-2022, https://doi.org/10.5194/bg-19-5151-2022, 2022
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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
Earth Syst. Sci. Data, 14, 2279–2301, https://doi.org/10.5194/essd-14-2279-2022, https://doi.org/10.5194/essd-14-2279-2022, 2022
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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
Biogeosciences, 19, 807–830, https://doi.org/10.5194/bg-19-807-2022, https://doi.org/10.5194/bg-19-807-2022, 2022
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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).
Nicole Burdanowitz, Tim Rixen, Birgit Gaye, and Kay-Christian Emeis
Clim. Past, 17, 1735–1749, https://doi.org/10.5194/cp-17-1735-2021, https://doi.org/10.5194/cp-17-1735-2021, 2021
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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.
Alexander Bratek, Justus E. E. van
Beusekom, Andreas Neumann, Tina Sanders, Jana Friedrich, Kay-Christian Emeis, and Kirstin Dähnke
Biogeosciences, 17, 2839–2851, https://doi.org/10.5194/bg-17-2839-2020, https://doi.org/10.5194/bg-17-2839-2020, 2020
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The following paper highlights the importance of benthic N-transformation rates in different sediment types in the southern North Sea as a source of fixed nitrogen for primary producers and also as a sink of fixed nitrogen. Sedimentary fluxes of dissolved inorganic nitrogen support ∼7 to 59 % of the average annual primary production. Semi-permeable and permeable sediments contribute ∼68 % of the total benthic N2 production rates, counteracting eutrophication in the southern North Sea.
Jiao Tang, Jun Li, Tao Su, Yong Han, Yangzhi Mo, Hongxing Jiang, Min Cui, Bin Jiang, Yingjun Chen, Jianhui Tang, Jianzhong Song, Ping'an Peng, and Gan Zhang
Atmos. Chem. Phys., 20, 2513–2532, https://doi.org/10.5194/acp-20-2513-2020, https://doi.org/10.5194/acp-20-2513-2020, 2020
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We investigated the light absorption, fluorescence, and molecular composition of dissolved organic carbon from the simulated combustion of biomass and coal and vehicle emissions with UV–vis spectra, EEM-PARAFAC, and FT-ICR MS. We observed high light absorption capacity from source emissions, and fluorescence spectra and molecular structures varied by source. We concluded that an EEM- and molecular-composition-based methodology could be helpful in the source apportionment of atmospheric aerosols.
Nele Tim, Eduardo Zorita, Kay-Christian Emeis, Franziska U. Schwarzkopf, Arne Biastoch, and Birgit Hünicke
Earth Syst. Dynam., 10, 847–858, https://doi.org/10.5194/esd-10-847-2019, https://doi.org/10.5194/esd-10-847-2019, 2019
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Our study reveals that the latitudinal position and intensity of Southern Hemisphere trades and westerlies are correlated. In the last decades the westerlies have shifted poleward and intensified. Furthermore, the latitudinal shifts and intensity of the trades and westerlies impact the sea surface temperatures around southern Africa and in the South Benguela upwelling region. The future development of wind stress depends on the strength of greenhouse gas forcing.
Natalie C. Harms, Niko Lahajnar, Birgit Gaye, Tim Rixen, Kirstin Dähnke, Markus Ankele, Ulrich Schwarz-Schampera, and Kay-Christian Emeis
Biogeosciences, 16, 2715–2732, https://doi.org/10.5194/bg-16-2715-2019, https://doi.org/10.5194/bg-16-2715-2019, 2019
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The Indian Ocean subtropical gyre is a large oligotrophic area that is likely to adjust to continued warming by increasing stratification, reduced nutrient supply and decreasing biological production. In this study, we investigated concentrations of nutrients and stable isotopes of nitrate. We determine the lateral influence of water masses entering the gyre from the northern Indian Ocean and from the Southern Ocean and quantify the input of nitrogen by N2 fixation into the surface layer.
Johannes Pein, Annika Eisele, Richard Hofmeister, Tina Sanders, Ute Daewel, Emil V. Stanev, Justus van Beusekom, Joanna Staneva, and Corinna Schrum
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-265, https://doi.org/10.5194/bg-2019-265, 2019
Revised manuscript not accepted
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The Elbe estuary is subject to vigorous tidal forcing from the sea side and considerable biological inputs from the land side. Our 3D numerical coupled physical-biogeochemical integrates these forcing signals and provides highly realistic hindcasts of the associated dynamics. Model simulations show that the freshwater part of Elbe estuary is inhabited by plankton. According to simulations these organism play a key role in converting organic inputs into nitrate, the major inorganic nutrient.
Tim Rixen, Birgit Gaye, Kay-Christian Emeis, and Venkitasubramani Ramaswamy
Biogeosciences, 16, 485–503, https://doi.org/10.5194/bg-16-485-2019, https://doi.org/10.5194/bg-16-485-2019, 2019
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Data obtained from sediment trap experiments in the Indian Ocean indicate that lithogenic matter ballast increases organic carbon flux rates on average by 45 % and by up to 62 % at trap locations in the river-influenced regions of the Indian Ocean. Such a strong lithogenic matter ballast effect implies that land use changes and the associated enhanced transport of lithogenic matter may significantly affect the CO2 uptake of the organic carbon pump in the receiving ocean areas.
Birgit Gaye, Anna Böll, Joachim Segschneider, Nicole Burdanowitz, Kay-Christian Emeis, Venkitasubramani Ramaswamy, Niko Lahajnar, Andreas Lückge, and Tim Rixen
Biogeosciences, 15, 507–527, https://doi.org/10.5194/bg-15-507-2018, https://doi.org/10.5194/bg-15-507-2018, 2018
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The Arabian Sea has one of the most severe oxygen minima of the world's oceans between about 100 and 1200 m of water depth and is therefore a major oceanic nitrogen sink. Stable nitrogen isotopic ratios in sediments record changes in oxygen concentrations and were studied for the last 25 kyr. Oxygen concentrations dropped at the end of the last glacial and became further reduced during the Holocene, probably due to the increasing age of the low-oxygen water mass.
Valerie Menke, Werner Ehrmann, Yvonne Milker, Swaantje Brzelinski, Jürgen Möbius, Uwe Mikolajewicz, Bernd Zolitschka, Karin Zonneveld, Kay Christian Emeis, and Gerhard Schmiedl
Clim. Past Discuss., https://doi.org/10.5194/cp-2017-139, https://doi.org/10.5194/cp-2017-139, 2017
Preprint withdrawn
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This study examines changes in the marine ecosystem during the past 1300 years in the Gulf of Taranto (Italy) to unravel natural and anthropogenic forcing. Our data suggest, that processes at the sea floor are linked to the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation. During the past 200 years, the effects of rising northern hemisphere temperature and increasing anthropogenic activity enhanced nutrient and organic matter fluxes leading to more eutrophic conditions.
Tim Rixen, Birgit Gaye, Kay-Christian Emeis, and Venkitasubramani Ramaswamy
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-317, https://doi.org/10.5194/bg-2017-317, 2017
Manuscript not accepted for further review
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Sediment trap experiments showed that in the river-influenced regions of the Indian Ocean lithogenic matter supplied from land controls the organic carbon export into the deep sea via its ballast effect in sinking particles. Carbonate produced by plankton is the main ballast material in the open ocean. The ballast effect increases the CO2 uptake of the organic carbon pump by enhancing the amount of nutrients used to bind CO2 and by favouring the sedimentation of organic matter.
Juliane Jacob, Tina Sanders, and Kirstin Dähnke
Biogeosciences, 13, 5649–5659, https://doi.org/10.5194/bg-13-5649-2016, https://doi.org/10.5194/bg-13-5649-2016, 2016
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During a flood in the Elbe in June 2013, a unique co-occurrence of ammonium, nitrite and nitrate in the water column was found. SPM and nutrient concentrations as well as isotopes were analysed. We calculated an isotope effect 15ε of −10.0 ± 0.1 ‰ during net nitrite and 15ε of −4.0 ± 0.1 ‰ and 18ε of −5.3 ± 0.1 ‰ during net nitrate consumption. A simple box-model calculation results in combined riparian denitrification and 22 to 36 % nitrification.
Nele Tim, Eduardo Zorita, Birgit Hünicke, Xing Yi, and Kay-Christian Emeis
Ocean Sci., 12, 807–823, https://doi.org/10.5194/os-12-807-2016, https://doi.org/10.5194/os-12-807-2016, 2016
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The impact of external climate forcing on the four eastern boundary upwelling systems is investigated for the recent past and future. Under increased radiative forcing, upwelling-favourable winds should strengthen due to unequal heating of land and oceans. However, coastal upwelling simulated in ensembles of climate simulations do not show any imprint of external forcing neither for the past millennium nor for the future, with the exception of the strongest future scenario.
Khan M. G. Mostofa, Cong-Qiang Liu, WeiDong Zhai, Marco Minella, Davide Vione, Kunshan Gao, Daisuke Minakata, Takemitsu Arakaki, Takahito Yoshioka, Kazuhide Hayakawa, Eiichi Konohira, Eiichiro Tanoue, Anirban Akhand, Abhra Chanda, Baoli Wang, and Hiroshi Sakugawa
Biogeosciences, 13, 1767–1786, https://doi.org/10.5194/bg-13-1767-2016, https://doi.org/10.5194/bg-13-1767-2016, 2016
X.-H. Guo, W.-D. Zhai, M.-H. Dai, C. Zhang, Y. Bai, Y. Xu, Q. Li, and G.-Z. Wang
Biogeosciences, 12, 5495–5514, https://doi.org/10.5194/bg-12-5495-2015, https://doi.org/10.5194/bg-12-5495-2015, 2015
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We report the most comprehensive data set of surface seawater pCO2 and air-sea CO2 fluxes in the East China Sea (ECS) based on 24 surveys conducted in 2006-2011. We categorized the ECS into five different domains characterized by different physics and biogeochemistry to better characterize the seasonality of the pCO2 dynamics and to better constrain the CO2 flux. The annual average CO2 influx into the entire ECS shelf was 6.9+/-4.0 mmol m-2 d-1, about twice the global average in an ocean margin.
W.-D. Zhai and X.-L. Yan
Biogeosciences Discuss., https://doi.org/10.5194/bgd-12-6405-2015, https://doi.org/10.5194/bgd-12-6405-2015, 2015
Manuscript not accepted for further review
T. Rixen, A. Baum, B. Gaye, and B. Nagel
Biogeosciences, 11, 5733–5747, https://doi.org/10.5194/bg-11-5733-2014, https://doi.org/10.5194/bg-11-5733-2014, 2014
W.-D. Zhai and H.-D. Zhao
Biogeosciences Discuss., https://doi.org/10.5194/bgd-11-11509-2014, https://doi.org/10.5194/bgd-11-11509-2014, 2014
Revised manuscript not accepted
W.-D. Zhai, N. Zheng, C. Huo, Y. Xu, H.-D. Zhao, Y.-W. Li, K.-P. Zang, J.-Y. Wang, and X.-M. Xu
Biogeosciences, 11, 1103–1123, https://doi.org/10.5194/bg-11-1103-2014, https://doi.org/10.5194/bg-11-1103-2014, 2014
A. Flohr, A. K. van der Plas, K.-C. Emeis, V. Mohrholz, and T. Rixen
Biogeosciences, 11, 885–897, https://doi.org/10.5194/bg-11-885-2014, https://doi.org/10.5194/bg-11-885-2014, 2014
W.-D. Zhai, M.-H. Dai, B.-S. Chen, X.-H. Guo, Q. Li, S.-L. Shang, C.-Y. Zhang, W.-J. Cai, and D.-X. Wang
Biogeosciences, 10, 7775–7791, https://doi.org/10.5194/bg-10-7775-2013, https://doi.org/10.5194/bg-10-7775-2013, 2013
B. Gaye, B. Nagel, K. Dähnke, T. Rixen, N. Lahajnar, and K.-C. Emeis
Biogeosciences, 10, 7689–7702, https://doi.org/10.5194/bg-10-7689-2013, https://doi.org/10.5194/bg-10-7689-2013, 2013
K. Dähnke and B. Thamdrup
Biogeosciences, 10, 3079–3088, https://doi.org/10.5194/bg-10-3079-2013, https://doi.org/10.5194/bg-10-3079-2013, 2013
Related subject area
Biogeochemistry: Coastal Ocean
Ocean alkalinity enhancement (OAE) does not cause cellular stress in a phytoplankton community of the subtropical Atlantic Ocean
Reviews and syntheses: On increasing hypoxia in eastern boundary upwelling systems – zooplankton under metabolic stress
Technical note: Testing a new approach for the determination of N2 fixation rates by coupling a membrane equilibrator to a mass spectrometer for long-term observations
Long-term variations in pH in coastal waters along the Korean Peninsula
The effect of carbonate mineral additions on biogeochemical conditions in surface sediments and benthic–pelagic exchange fluxes
Evaluating ocean alkalinity enhancement as a carbon dioxide removal strategy in the North Sea
Assessing the impacts of simulated ocean alkalinity enhancement on viability and growth of nearshore species of phytoplankton
Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement
High metabolic zinc demand within native Amundsen and Ross sea phytoplankton communities determined by stable isotope uptake rate measurements
The influence of zooplankton and oxygen on the particulate organic carbon flux in the Benguela Upwelling System
Reviews and syntheses: Biological indicators of low-oxygen stress in marine water-breathing animals
Temperature-enhanced effects of iron on Southern Ocean phytoplankton
Riverine nutrient impact on global ocean nitrogen cycle feedbacks and marine primary production in an Earth system model
Effects of Submarine Groundwater on Nutrient Concentration and Primary Production in a Deep Bay of the Japan Sea
The Northeast Greenland Shelf as a potential late-summer CO2 source to the atmosphere
Spring-neap tidal cycles modulate the strength of the carbon source at the estuary-coast interface
Technical note: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project (OAEPIIP)
Estimates of carbon sequestration potential in an expanding Arctic fjord (Hornsund, Svalbard) affected by dark plumes of glacial meltwater
An assessment of ocean alkalinity enhancement using aqueous hydroxides: kinetics, efficiency, and precipitation thresholds
Dissolved nitric oxide in the lower Elbe Estuary and the Port of Hamburg area
The bacteria-protist link as a main route of dissolved organic matter across contrasting productivity areas in the Patagonian Shelf
Variable contribution of wastewater treatment plant effluents to downstream nitrous oxide concentrations and emissions
Depositional controls and budget of organic carbon burial in fine-grained sediments of the North Sea – the Helgoland Mud Area as a test field
Improved understanding of eutrophication trends, indicators and problem areas using machine learning
Distribution of nutrients and dissolved organic matter in a eutrophic equatorial estuary: the Johor River and the East Johor Strait
Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022
Investigating the effect of silicate- and calcium-based ocean alkalinity enhancement on diatom silicification
Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment
Quantification and mitigation of bottom-trawling impacts on sedimentary organic carbon stocks in the North Sea
Influence of ocean alkalinity enhancement with olivine or steel slag on a coastal plankton community in Tasmania
Multi-model comparison of trends and controls of near-bed oxygen concentration on the northwest European continental shelf under climate change
Picoplanktonic methane production in eutrophic surface waters
Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
Hypoxia also occurs in small highly turbid estuaries: the example of the Charente (Bay of Biscay)
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
Oceanographic processes driving low-oxygen conditions inside Patagonian fjords
Above- and belowground plant mercury dynamics in a salt marsh estuary in Massachusetts, USA
Variability and drivers of carbonate chemistry at shellfish aquaculture sites in the Salish Sea, British Columbia
Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters
Insights into carbonate environmental conditions in the Chukchi Sea
UAV approaches for improved mapping of vegetation cover and estimation of carbon storage of small saltmarshes: examples from Loch Fleet, northeast Scotland
Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
Marine anoxia initiates giant sulfur-oxidizing bacterial mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland
Uncertainty in the evolution of northwestern North Atlantic circulation leads to diverging biogeochemical projections
The additionality problem of ocean alkalinity enhancement
Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings
Revisiting the applicability and constraints of molybdenum- and uranium-based paleo redox proxies: comparing two contrasting sill fjords
Influence of a small submarine canyon on biogenic matter export flux in the lower St. Lawrence Estuary, eastern Canada
Single-celled bioturbators: benthic foraminifera mediate oxygen penetration and prokaryotic diversity in intertidal sediment
Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan
Librada Ramírez, Leonardo J. Pozzo-Pirotta, Aja Trebec, Víctor Manzanares-Vázquez, José L. Díez, Javier Arístegui, Ulf Riebesell, Stephen D. Archer, and María Segovia
Biogeosciences, 22, 1865–1886, https://doi.org/10.5194/bg-22-1865-2025, https://doi.org/10.5194/bg-22-1865-2025, 2025
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We studied the potential effects of increasing ocean alkalinity on a natural plankton community in subtropical waters of the Atlantic near Gran Canaria, Spain. Alkalinity is the capacity of water to resist acidification, and plankton are usually microscopic plants (phytoplankton) and animals (zooplankton), often less than 2.5 cm in length. This study suggests that increasing ocean alkalinity did not have a significant negative impact on the plankton community studied.
Leissing Frederick, Mauricio A. Urbina, and Ruben Escribano
Biogeosciences, 22, 1839–1852, https://doi.org/10.5194/bg-22-1839-2025, https://doi.org/10.5194/bg-22-1839-2025, 2025
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Evidence shows that due to global warming, zooplankton inhabiting the coastal upwelling zone are exposed to increasing hypoxia affecting their physiology, metabolism, and population dynamics. The adaptive responses of zooplankton to cope with mild/severe hypoxia may depend on trade-offs with other metabolic/energy demands, implying less energy for growth, feeding, and reproduction, with ecological consequences for the zooplankton population and the marine food web.
Sören Iwe, Oliver Schmale, and Bernd Schneider
Biogeosciences, 22, 1767–1779, https://doi.org/10.5194/bg-22-1767-2025, https://doi.org/10.5194/bg-22-1767-2025, 2025
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We present a novel method for quantifying N2 fixation by cyanobacteria, which is crucial in Baltic Sea eutrophication. Our Gas Equilibrium – Membrane-Inlet Mass Spectrometer (GE-MIMS), designed for operation on voluntary observing ships (VOSs), enables large-scale monitoring of surface water N2 depletion caused by N2 fixation. Laboratory tests confirm the device’s accuracy and precision, ensuring that it can complement current methods and contribute valuable data for better understanding N2 fixation in the Baltic Sea.
Yong-Woo Lee, Mi-Ok Park, Seong-Gil Kim, Tae-Hoon Kim, Yong Hwa Oh, Sang Heon Lee, and DongJoo Joung
Biogeosciences, 22, 675–690, https://doi.org/10.5194/bg-22-675-2025, https://doi.org/10.5194/bg-22-675-2025, 2025
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Long-term pH variation in coastal waters along the Korean Peninsula was assessed for the first time, and it exhibited no significant pH change over an 11-year period. This contrasts with the ongoing pH decline in open oceans and other coastal areas. Analysis of environmental data showed that pH is mainly controlled by dissolved oxygen in bottom waters. This suggests that ocean warming could cause a pH decline in Korean coastal waters, affecting many fish and seaweed aquaculture operations.
Kadir Biçe, Tristen Myers Stewart, George G. Waldbusser, and Christof Meile
Biogeosciences, 22, 641–657, https://doi.org/10.5194/bg-22-641-2025, https://doi.org/10.5194/bg-22-641-2025, 2025
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We studied the effect of addition of carbonate minerals on coastal sediments. We carried out laboratory experiments to quantify the dissolution kinetics and integrated these observations into a numerical model that describes biogeochemical cycling in surficial sediments. Using the model, we demonstrate the buffering effect of the mineral additions and their duration. We quantify the effect under different environmental conditions and assess the potential for increased atmospheric CO2 uptake.
Feifei Liu, Ute Daewel, Jan Kossack, Kubilay Timur Demir, Helmuth Thomas, and Corinna Schrum
EGUsphere, https://doi.org/10.5194/egusphere-2025-81, https://doi.org/10.5194/egusphere-2025-81, 2025
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Ocean Alkalinity Enhancement boosts oceanic CO₂ absorption, offering a climate solution. Using a regional model, we examined OAE in the North Sea, revealing that shallow coastal areas achieve higher CO₂ uptake than offshore, where alkalinity is more susceptible to deep-ocean loss. Long-term carbon storage is limited, and pH shifts vary by location. Our findings guide OAE deployment to optimize carbon removal while minimizing ecological effects, supporting global climate mitigation efforts.
Jessica L. Oberlander, Mackenzie E. Burke, Cat A. London, and Hugh L. MacIntyre
Biogeosciences, 22, 499–512, https://doi.org/10.5194/bg-22-499-2025, https://doi.org/10.5194/bg-22-499-2025, 2025
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Ocean alkalinity enhancement (OAE) is a promising negative emission technology that results in the net sequestration of atmospheric carbon. In this paper, we assess the potential impact of OAE on phytoplankton through an analysis of prior studies and the effects of simulated OAE on photosynthetic competence. Our findings suggest that there may be little if any significant impact on most phytoplankton studied to date if OAE is conducted in well-flushed, nearshore environments.
Laura Marín-Samper, Javier Arístegui, Nauzet Hernández-Hernández, and Ulf Riebesell
Biogeosciences, 21, 5707–5724, https://doi.org/10.5194/bg-21-5707-2024, https://doi.org/10.5194/bg-21-5707-2024, 2024
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This study exposed a natural community to two non-CO2-equilibrated ocean alkalinity enhancement (OAE) deployments using different minerals. Adding alkalinity in this manner decreases dissolved CO2, essential for photosynthesis. While photosynthesis was not suppressed, bloom formation was mildly delayed, potentially impacting marine food webs. The study emphasizes the need for further research on OAE without prior equilibration and on its ecological implications.
Riss M. Kell, Rebecca J. Chmiel, Deepa Rao, Dawn M. Moran, Matthew R. McIlvin, Tristan J. Horner, Nicole L. Schanke, Ichiko Sugiyama, Robert B. Dunbar, Giacomo R. DiTullio, and Mak A. Saito
Biogeosciences, 21, 5685–5706, https://doi.org/10.5194/bg-21-5685-2024, https://doi.org/10.5194/bg-21-5685-2024, 2024
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Despite interest in modeling the biogeochemical uptake and cycling of the trace metal zinc (Zn), measurements of Zn uptake in natural marine phytoplankton communities have not been conducted previously. To fill this gap, we employed a stable isotope uptake rate measurement method to quantify Zn uptake into natural phytoplankton assemblages within the Southern Ocean. Zn demand was high and rapid enough to depress the inventory of Zn available to phytoplankton on seasonal timescales.
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
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Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Michael R. Roman, Andrew H. Altieri, Denise Breitburg, Erica M. Ferrer, Natalya D. Gallo, Shin-ichi Ito, Karin Limburg, Kenneth Rose, Moriaki Yasuhara, and Lisa A. Levin
Biogeosciences, 21, 4975–5004, https://doi.org/10.5194/bg-21-4975-2024, https://doi.org/10.5194/bg-21-4975-2024, 2024
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Oxygen-depleted ocean waters have increased worldwide. In order to improve our understanding of the impacts of this oxygen loss on marine life it is essential that we develop reliable indicators that track the negative impacts of low oxygen. We review various indicators of low-oxygen stress for marine animals including their use, research needs, and application to confront the challenges of ocean oxygen loss.
Charlotte Eich, Mathijs van Manen, J. Scott P. McCain, Loay J. Jabre, Willem H. van de Poll, Jinyoung Jung, Sven B. E. H. Pont, Hung-An Tian, Indah Ardiningsih, Gert-Jan Reichart, Erin M. Bertrand, Corina P. D. Brussaard, and Rob Middag
Biogeosciences, 21, 4637–4663, https://doi.org/10.5194/bg-21-4637-2024, https://doi.org/10.5194/bg-21-4637-2024, 2024
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Phytoplankton growth in the Southern Ocean (SO) is often limited by low iron (Fe) concentrations. Sea surface warming impacts Fe availability and can affect phytoplankton growth. We used shipboard Fe clean incubations to test how changes in Fe and temperature affect SO phytoplankton. Their abundances usually increased with Fe addition and temperature increase, with Fe being the major factor. These findings imply potential shifts in ecosystem structure, impacting food webs and elemental cycling.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 21, 4469–4493, https://doi.org/10.5194/bg-21-4469-2024, https://doi.org/10.5194/bg-21-4469-2024, 2024
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Marine biological production is highly dependent on the availability of nitrogen and phosphorus. Rivers are the main source of phosphorus to the oceans but poorly represented in global model oceans. We include dissolved nitrogen and phosphorus from river export in a global model ocean and find that the addition of riverine phosphorus affects marine biology on millennial timescales more than riverine nitrogen alone. Globally, riverine phosphorus input increases primary production rates.
Menghong Dong, Xinyu Guo, Takuya Matsuura, Taichi Tebakari, and Jing Zhang
EGUsphere, https://doi.org/10.5194/egusphere-2024-2581, https://doi.org/10.5194/egusphere-2024-2581, 2024
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Submarine groundwater discharge (SGD), a common coastal hydrological process that involves submarine inflow of groundwater into the sea, is associated with a large nutrient load. To clarify the distribution of SGD-derived nutrients after release at the bottom of the sea and their contribution to phytoplankton growth in the marine ecosystem, we modeled the SGD process in Toyama Bay using a specialized computer code that can distinguish SGD-derived nutrients from nutrients from other sources.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Marchiano Holding, and Søren Rysgaard
Biogeosciences, 21, 4037–4050, https://doi.org/10.5194/bg-21-4037-2024, https://doi.org/10.5194/bg-21-4037-2024, 2024
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In this work, we measured the chemistry of seawater from samples obtained from different depths and locations off the east coast of the Northeast Greenland National Park to determine what is influencing concentrations of dissolved CO2. Historically, the region has always been thought to take up CO2 from the atmosphere, but we show that it is possible for the region to become a source in late summer. We discuss the variables that may be related to such changes.
Vlad A. Macovei, Louise C. V. Rewrie, Rüdiger Röttgers, and Yoana G. Voynova
EGUsphere, https://doi.org/10.5194/egusphere-2024-2643, https://doi.org/10.5194/egusphere-2024-2643, 2024
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A commercial vessel equipped with scientific instruments regularly travelled between two large macro-tidal estuaries. We found that biogeochemical variability in the outer estuaries is driven by the 14-day spring-neap tidal cycle, with strong effects on dissolved inorganic and organic carbon concentrations and distribution. Since this land-sea interface effect increases the strength of the carbon source to the atmosphere by 74 % during spring tide, it should be accounted for in regional models.
Lennart Thomas Bach, Aaron James Ferderer, Julie LaRoche, and Kai Georg Schulz
Biogeosciences, 21, 3665–3676, https://doi.org/10.5194/bg-21-3665-2024, https://doi.org/10.5194/bg-21-3665-2024, 2024
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Ocean alkalinity enhancement (OAE) is an emerging marine CO2 removal method, but its environmental effects are insufficiently understood. The OAE Pelagic Impact Intercomparison Project (OAEPIIP) provides funding for a standardized and globally replicated microcosm experiment to study the effects of OAE on plankton communities. Here, we provide a detailed manual for the OAEPIIP experiment. We expect OAEPIIP to help build scientific consensus on the effects of OAE on plankton.
Marlena Szeligowska, Déborah Benkort, Anna Przyborska, Mateusz Moskalik, Bernabé Moreno, Emilia Trudnowska, and Katarzyna Błachowiak-Samołyk
Biogeosciences, 21, 3617–3639, https://doi.org/10.5194/bg-21-3617-2024, https://doi.org/10.5194/bg-21-3617-2024, 2024
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The European Arctic is experiencing rapid regional warming, causing glaciers that terminate in the sea to retreat onto land. Due to this process, the area of a well-studied fjord, Hornsund, has increased by around 100 km2 (40%) since 1976. Combining satellite and in situ data with a mathematical model, we estimated that, despite some negative consequences of glacial meltwater release, such emerging coastal waters could mitigate climate change by increasing carbon uptake and storage by sediments.
Mallory C. Ringham, Nathan Hirtle, Cody Shaw, Xi Lu, Julian Herndon, Brendan R. Carter, and Matthew D. Eisaman
Biogeosciences, 21, 3551–3570, https://doi.org/10.5194/bg-21-3551-2024, https://doi.org/10.5194/bg-21-3551-2024, 2024
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Ocean alkalinity enhancement leverages the large surface area and carbon storage capacity of the oceans to store atmospheric CO2 as dissolved bicarbonate. We monitored CO2 uptake in seawater treated with NaOH to establish operational boundaries for carbon removal experiments. Results show that CO2 equilibration occurred on the order of weeks to months, was consistent with values expected from equilibration calculations, and was limited by mineral precipitation at high pH and CaCO3 saturation.
Riel Carlo O. Ingeniero, Gesa Schulz, and Hermann W. Bange
Biogeosciences, 21, 3425–3440, https://doi.org/10.5194/bg-21-3425-2024, https://doi.org/10.5194/bg-21-3425-2024, 2024
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Our research is the first to measure dissolved NO concentrations in temperate estuarine waters, providing insights into its distribution under varying conditions and enhancing our understanding of its production processes. Dissolved NO was supersaturated in the Elbe Estuary, indicating that it is a source of atmospheric NO. The observed distribution of dissolved NO most likely resulted from nitrification.
Celeste López-Abbate, John E. Garzón-Cardona, Ricardo Silva, Juan-Carlos Molinero, Laura A. Ruiz-Etcheverry, Ana M. Martínez, Azul S. Gilabert, and Rubén J. Lara
EGUsphere, https://doi.org/10.5194/egusphere-2024-1860, https://doi.org/10.5194/egusphere-2024-1860, 2024
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This study examines how microbial community structure, growth, and grazing impact the DOM pool in the Patagonian Shelf. Despite higher phytoplankton biomass, faster-growing bacteria were selectively grazed by protists leading to DOM accumulation, likely due to a reduction in DOM-consuming bacteria and the addition of egestion compounds. Experimental data showed that while bacteria remained as the primarily shapers of DOM quality, grazing pressure impacted on DOM accumulation.
Weiyi Tang, Jeff Talbott, Timothy Jones, and Bess B. Ward
Biogeosciences, 21, 3239–3250, https://doi.org/10.5194/bg-21-3239-2024, https://doi.org/10.5194/bg-21-3239-2024, 2024
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Wastewater treatment plants (WWTPs) are known to be hotspots of greenhouse gas emissions. However, the impact of WWTPs on the emission of the greenhouse gas N2O in downstream aquatic environments is less constrained. We found spatially and temporally variable but overall higher N2O concentrations and fluxes in waters downstream of WWTPs, pointing to the need for efficient N2O removal in addition to the treatment of nitrogen in WWTPs.
Daniel Müller, Bo Liu, Walter Geibert, Moritz Holtappels, Lasse Sander, Elda Miramontes, Heidi Taubner, Susann Henkel, Kai-Uwe Hinrichs, Denise Bethke, Ingrid Dohrmann, and Sabine Kasten
EGUsphere, https://doi.org/10.5194/egusphere-2024-1632, https://doi.org/10.5194/egusphere-2024-1632, 2024
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Coastal and shelf sediments are the most important sinks for organic carbon (OC) on Earth. We produced a new high-resolution sediment and pore-water dataset from the Helgoland Mud Area (HMA), North Sea, to determine, which depositional factors control the preservation of OC. The burial efficiency is highest in an area of high sedimentation and terrigenous OC. The HMA covers 0.09 % of the North Sea, but accounts for 0.76 % of its OC accumulation, highlighting the importance of the depocentre.
Deep S. Banerjee and Jozef Skakala
EGUsphere, https://doi.org/10.22541/essoar.171405637.76928549/v1, https://doi.org/10.22541/essoar.171405637.76928549/v1, 2024
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Nitrate is a crucial nutrient in oceans. Excess nutrients can trigger uncontrolled algae growth (eutrophication), damaging marine ecosystems. We used a machine learning tool to generate a skilled, gap-free, bi-decadal surface nitrate dataset from sparse observations. This dataset reveals areas on the North West European Shelf at risk of eutrophication, bi-decadal trends in coastal nitrate, and an impact of winter nitrate on spring phytoplankton blooms.
Amanda Y. L. Cheong, Kogila Vani Annammala, Ee Ling Yong, Yongli Zhou, Robert S. Nichols, and Patrick Martin
Biogeosciences, 21, 2955–2971, https://doi.org/10.5194/bg-21-2955-2024, https://doi.org/10.5194/bg-21-2955-2024, 2024
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We measured nutrients and dissolved organic matter for 1 year in a eutrophic tropical estuary to understand their sources and cycling. Our data show that the dissolved organic matter originates partly from land and partly from microbial processes in the water. Internal recycling is likely important for maintaining high nutrient concentrations, and we found that there is often excess nitrogen compared to silicon and phosphorus. Our data help to explain how eutrophication persists in this system.
Darren Pilcher, Jessica Cross, Natalie Monacci, Linquan Mu, Kelly Kearney, Albert Hermann, and Wei Cheng
EGUsphere, https://doi.org/10.5194/egusphere-2024-1096, https://doi.org/10.5194/egusphere-2024-1096, 2024
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The Bering Sea shelf is a highly productive marine ecosystem that is vulnerable to ocean acidification. We use a computational model to simulate the carbon cycle and acidification rates from 1970–2022. The results suggest that bottom water acidification rates are more than twice as great as surface rates. Bottom waters are also naturally more acidic, thus these waters will pass key thresholds known to negatively impact marine organisms, such as red king crab, much sooner than surface waters.
Aaron Ferderer, Kai G. Schulz, Ulf Riebesell, Kirralee G. Baker, Zanna Chase, and Lennart T. Bach
Biogeosciences, 21, 2777–2794, https://doi.org/10.5194/bg-21-2777-2024, https://doi.org/10.5194/bg-21-2777-2024, 2024
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Ocean alkalinity enhancement (OAE) is a promising method of atmospheric carbon removal; however, its ecological impacts remain largely unknown. We assessed the effects of simulated silicate- and calcium-based mineral OAE on diatom silicification. We found that increased silicate concentrations from silicate-based OAE increased diatom silicification. In contrast, the enhancement of alkalinity had no effect on community silicification and minimal effects on the silicification of different genera.
David González-Santana, María Segovia, Melchor González-Dávila, Librada Ramírez, Aridane G. González, Leonardo J. Pozzo-Pirotta, Veronica Arnone, Victor Vázquez, Ulf Riebesell, and J. Magdalena Santana-Casiano
Biogeosciences, 21, 2705–2715, https://doi.org/10.5194/bg-21-2705-2024, https://doi.org/10.5194/bg-21-2705-2024, 2024
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In a recent experiment off the coast of Gran Canaria (Spain), scientists explored a method called ocean alkalinization enhancement (OAE), where carbonate minerals were added to seawater. This process changed the levels of certain ions in the water, affecting its pH and buffering capacity. The researchers were particularly interested in how this could impact the levels of essential trace metals in the water.
Lucas Porz, Wenyan Zhang, Nils Christiansen, Jan Kossack, Ute Daewel, and Corinna Schrum
Biogeosciences, 21, 2547–2570, https://doi.org/10.5194/bg-21-2547-2024, https://doi.org/10.5194/bg-21-2547-2024, 2024
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Seafloor sediments store a large amount of carbon, helping to naturally regulate Earth's climate. If disturbed, some sediment particles can turn into CO2, but this effect is not well understood. Using computer simulations, we found that bottom-contacting fishing gears release about 1 million tons of CO2 per year in the North Sea, one of the most heavily fished regions globally. We show how protecting certain areas could reduce these emissions while also benefitting seafloor-living animals.
Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
Biogeosciences, 21, 2335–2354, https://doi.org/10.5194/bg-21-2335-2024, https://doi.org/10.5194/bg-21-2335-2024, 2024
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Ocean alkalinity enhancement aims to increase atmospheric CO2 sequestration by adding alkaline materials to the ocean. We assessed the environmental effects of olivine and steel slag powder on coastal plankton. Overall, slag is more efficient than olivine in releasing total alkalinity and, thus, in its ability to sequester CO2. Slag also had less environmental effect on the enclosed plankton communities when considering its higher CO2 removal potential based on this 3-week experiment.
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
Biogeosciences, 21, 2143–2158, https://doi.org/10.5194/bg-21-2143-2024, https://doi.org/10.5194/bg-21-2143-2024, 2024
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This work shows that, under a high-emission scenario, oxygen concentration in deep water of parts of the North Sea and Celtic Sea can become critically low (hypoxia) towards the end of this century. The extent and frequency of hypoxia depends on the intensity of climate change projected by different climate models. This is the result of a complex combination of factors like warming, increase in stratification, changes in the currents and changes in biological processes.
Sandy E. Tenorio and Laura Farías
Biogeosciences, 21, 2029–2050, https://doi.org/10.5194/bg-21-2029-2024, https://doi.org/10.5194/bg-21-2029-2024, 2024
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Time series studies show that CH4 is highly dynamic on the coastal ocean surface and planktonic communities are linked to CH4 accumulation, as found in coastal upwelling off Chile. We have identified the crucial role of picoplankton (> 3 µm) in CH4 recycling, especially with the addition of methylated substrates (trimethylamine and methylphosphonic acid) during upwelling and non-upwelling periods. These insights improve understanding of surface ocean CH4 recycling, aiding CH4 emission estimates.
Charlotte A. J. Williams, Tom Hull, Jan Kaiser, Claire Mahaffey, Naomi Greenwood, Matthew Toberman, and Matthew R. Palmer
Biogeosciences, 21, 1961–1971, https://doi.org/10.5194/bg-21-1961-2024, https://doi.org/10.5194/bg-21-1961-2024, 2024
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Oxygen (O2) is a key indicator of ocean health. The risk of O2 loss in the productive coastal/continental slope regions is increasing. Autonomous underwater vehicles equipped with O2 optodes provide lots of data but have problems resolving strong vertical O2 changes. Here we show how to overcome this and calculate how much O2 is supplied to the low-O2 bottom waters via mixing. Bursts in mixing supply nearly all of the O2 to bottom waters in autumn, stopping them reaching ecologically low levels.
Sabine Schmidt and Ibrahima Iris Diallo
Biogeosciences, 21, 1785–1800, https://doi.org/10.5194/bg-21-1785-2024, https://doi.org/10.5194/bg-21-1785-2024, 2024
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Along the French coast facing the Bay of Biscay, the large Gironde and Loire estuaries suffer from hypoxia. This prompted a study of the small Charente estuary located between them. This work reveals a minimum oxygen zone in the Charente estuary, which extends for about 25 km. Temperature is the main factor controlling the hypoxia. This calls for the monitoring of small turbid macrotidal estuaries that are vulnerable to hypoxia, a risk expected to increase with global warming.
Simone R. Alin, Jan A. Newton, Richard A. Feely, Samantha Siedlecki, and Dana Greeley
Biogeosciences, 21, 1639–1673, https://doi.org/10.5194/bg-21-1639-2024, https://doi.org/10.5194/bg-21-1639-2024, 2024
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We provide a new multi-stressor data product that allows us to characterize the seasonality of temperature, O2, and CO2 in the southern Salish Sea and delivers insights into the impacts of major marine heatwave and precipitation anomalies on regional ocean acidification and hypoxia. We also describe the present-day frequencies of temperature, O2, and ocean acidification conditions that cross thresholds of sensitive regional species that are economically or ecologically important.
Pamela Linford, Iván Pérez-Santos, Paulina Montero, Patricio A. Díaz, Claudia Aracena, Elías Pinilla, Facundo Barrera, Manuel Castillo, Aida Alvera-Azcárate, Mónica Alvarado, Gabriel Soto, Cécile Pujol, Camila Schwerter, Sara Arenas-Uribe, Pilar Navarro, Guido Mancilla-Gutiérrez, Robinson Altamirano, Javiera San Martín, and Camila Soto-Riquelme
Biogeosciences, 21, 1433–1459, https://doi.org/10.5194/bg-21-1433-2024, https://doi.org/10.5194/bg-21-1433-2024, 2024
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The Patagonian fjords comprise a world region where low-oxygen water and hypoxia conditions are observed. An in situ dataset was used to quantify the mechanism involved in the presence of these conditions in northern Patagonian fjords. Water mass analysis confirmed the contribution of Equatorial Subsurface Water in the advection of the low-oxygen water, and hypoxic conditions occurred when the community respiration rate exceeded the gross primary production.
Ting Wang, Buyun Du, Inke Forbrich, Jun Zhou, Joshua Polen, Elsie M. Sunderland, Prentiss H. Balcom, Celia Chen, and Daniel Obrist
Biogeosciences, 21, 1461–1476, https://doi.org/10.5194/bg-21-1461-2024, https://doi.org/10.5194/bg-21-1461-2024, 2024
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The strong seasonal increases of Hg in aboveground biomass during the growing season and the lack of changes observed after senescence in this salt marsh ecosystem suggest physiologically controlled Hg uptake pathways. The Hg sources found in marsh aboveground tissues originate from a mix of sources, unlike terrestrial ecosystems, where atmospheric GEM is the main source. Belowground plant tissues mostly take up Hg from soils. Overall, the salt marsh currently serves as a small net Hg sink.
Eleanor Simpson, Debby Ianson, Karen E. Kohfeld, Ana C. Franco, Paul A. Covert, Marty Davelaar, and Yves Perreault
Biogeosciences, 21, 1323–1353, https://doi.org/10.5194/bg-21-1323-2024, https://doi.org/10.5194/bg-21-1323-2024, 2024
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Shellfish aquaculture operates in nearshore areas where data on ocean acidification parameters are limited. We show daily and seasonal variability in pH and saturation states of calcium carbonate at nearshore aquaculture sites in British Columbia, Canada, and determine the contributing drivers of this variability. We find that nearshore locations have greater variability than open waters and that the uptake of carbon by phytoplankton is the major driver of pH and saturation state variability.
S. Alejandra Castillo Cieza, Rachel H. R. Stanley, Pierre Marrec, Diana N. Fontaine, E. Taylor Crockford, Dennis J. McGillicuddy Jr., Arshia Mehta, Susanne Menden-Deuer, Emily E. Peacock, Tatiana A. Rynearson, Zoe O. Sandwith, Weifeng Zhang, and Heidi M. Sosik
Biogeosciences, 21, 1235–1257, https://doi.org/10.5194/bg-21-1235-2024, https://doi.org/10.5194/bg-21-1235-2024, 2024
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The coastal ocean in the northeastern USA provides many services, including fisheries and habitats for threatened species. In summer 2019, a bloom occurred of a large unusual phytoplankton, the diatom Hemiaulus, with nitrogen-fixing symbionts. This led to vast changes in productivity and grazing rates in the ecosystem. This work shows that the emergence of one species can have profound effects on ecosystem function. Such changes may become more prevalent as the ocean warms due to climate change.
Claudine Hauri, Brita Irving, Sam Dupont, Rémi Pagés, Donna D. W. Hauser, and Seth L. Danielson
Biogeosciences, 21, 1135–1159, https://doi.org/10.5194/bg-21-1135-2024, https://doi.org/10.5194/bg-21-1135-2024, 2024
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Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. We present pH and pCO2 time series (2016–2020) from the Chukchi Ecosystem Observatory and analyze the drivers of the current conditions to get a better understanding of how climate change and ocean acidification could affect the ecological niches of organisms.
William Hiles, Lucy C. Miller, Craig Smeaton, and William E. N. Austin
Biogeosciences, 21, 929–948, https://doi.org/10.5194/bg-21-929-2024, https://doi.org/10.5194/bg-21-929-2024, 2024
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Saltmarsh soils may help to limit the rate of climate change by storing carbon. To understand their impacts, they must be accurately mapped. We use drone data to estimate the size of three saltmarshes in NE Scotland. We find that drone imagery, combined with tidal data, can reliably inform our understanding of saltmarsh size. When compared with previous work using vegetation communities, we find that our most reliable new estimates of stored carbon are 15–20 % smaller than previously estimated.
De'Marcus Robinson, Anh L. D. Pham, David J. Yousavich, Felix Janssen, Frank Wenzhöfer, Eleanor C. Arrington, Kelsey M. Gosselin, Marco Sandoval-Belmar, Matthew Mar, David L. Valentine, Daniele Bianchi, and Tina Treude
Biogeosciences, 21, 773–788, https://doi.org/10.5194/bg-21-773-2024, https://doi.org/10.5194/bg-21-773-2024, 2024
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The present study suggests that high release of ferrous iron from the seafloor of the oxygen-deficient Santa Barabara Basin (California) supports surface primary productivity, creating positive feedback on seafloor iron release by enhancing low-oxygen conditions in the basin.
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhöfer, Felix Janssen, Na Liu, Jonathan Tarn, Franklin Kinnaman, David L. Valentine, and Tina Treude
Biogeosciences, 21, 789–809, https://doi.org/10.5194/bg-21-789-2024, https://doi.org/10.5194/bg-21-789-2024, 2024
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Declining oxygen (O2) concentrations in coastal oceans can threaten people’s ways of life and food supplies. Here, we investigate how mats of bacteria that proliferate on the seafloor of the Santa Barbara Basin sustain and potentially worsen these O2 depletion events through their unique chemoautotrophic metabolism. Our study shows how changes in seafloor microbiology and geochemistry brought on by declining O2 concentrations can help these mats grow as well as how that growth affects the basin.
Krysten Rutherford, Katja Fennel, Lina Garcia Suarez, and Jasmin G. John
Biogeosciences, 21, 301–314, https://doi.org/10.5194/bg-21-301-2024, https://doi.org/10.5194/bg-21-301-2024, 2024
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We downscaled two mid-century (~2075) ocean model projections to a high-resolution regional ocean model of the northwest North Atlantic (NA) shelf. In one projection, the NA shelf break current practically disappears; in the other it remains almost unchanged. This leads to a wide range of possible future shelf properties. More accurate projections of coastal circulation features would narrow the range of possible outcomes of biogeochemical projections for shelf regions.
Lennart Thomas Bach
Biogeosciences, 21, 261–277, https://doi.org/10.5194/bg-21-261-2024, https://doi.org/10.5194/bg-21-261-2024, 2024
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Ocean alkalinity enhancement (OAE) is a widely considered marine carbon dioxide removal method. OAE aims to accelerate chemical rock weathering, which is a natural process that slowly sequesters atmospheric carbon dioxide. This study shows that the addition of anthropogenic alkalinity via OAE can reduce the natural release of alkalinity and, therefore, reduce the efficiency of OAE for climate mitigation. However, the additionality problem could be mitigated via a variety of activities.
Tsuneo Ono, Daisuke Muraoka, Masahiro Hayashi, Makiko Yorifuji, Akihiro Dazai, Shigeyuki Omoto, Takehiro Tanaka, Tomohiro Okamura, Goh Onitsuka, Kenji Sudo, Masahiko Fujii, Ryuji Hamanoue, and Masahide Wakita
Biogeosciences, 21, 177–199, https://doi.org/10.5194/bg-21-177-2024, https://doi.org/10.5194/bg-21-177-2024, 2024
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We carried out parallel year-round observations of pH and related parameters in five stations around the Japan coast. It was found that short-term acidified situations with Omega_ar less than 1.5 occurred at four of five stations. Most of such short-term acidified events were related to the short-term low salinity event, and the extent of short-term pH drawdown at high freshwater input was positively correlated with the nutrient concentration of the main rivers that flow into the coastal area.
K. Mareike Paul, Martijn Hermans, Sami A. Jokinen, Inda Brinkmann, Helena L. Filipsson, and Tom Jilbert
Biogeosciences, 20, 5003–5028, https://doi.org/10.5194/bg-20-5003-2023, https://doi.org/10.5194/bg-20-5003-2023, 2023
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Seawater naturally contains trace metals such as Mo and U, which accumulate under low oxygen conditions on the seafloor. Previous studies have used sediment Mo and U contents as an archive of changing oxygen concentrations in coastal waters. Here we show that in fjords the use of Mo and U for this purpose may be impaired by additional processes. Our findings have implications for the reliable use of Mo and U to reconstruct oxygen changes in fjords.
Hannah Sharpe, Michel Gosselin, Catherine Lalande, Alexandre Normandeau, Jean-Carlos Montero-Serrano, Khouloud Baccara, Daniel Bourgault, Owen Sherwood, and Audrey Limoges
Biogeosciences, 20, 4981–5001, https://doi.org/10.5194/bg-20-4981-2023, https://doi.org/10.5194/bg-20-4981-2023, 2023
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We studied the impact of submarine canyon processes within the Pointe-des-Monts system on biogenic matter export and phytoplankton assemblages. Using data from three oceanographic moorings, we show that the canyon experienced two low-amplitude sediment remobilization events in 2020–2021 that led to enhanced particle fluxes in the deep-water column layer > 2.6 km offshore. Sinking phytoplankton fluxes were lower near the canyon compared to background values from the lower St. Lawrence Estuary.
Dewi Langlet, Florian Mermillod-Blondin, Noémie Deldicq, Arthur Bauville, Gwendoline Duong, Lara Konecny, Mylène Hugoni, Lionel Denis, and Vincent M. P. Bouchet
Biogeosciences, 20, 4875–4891, https://doi.org/10.5194/bg-20-4875-2023, https://doi.org/10.5194/bg-20-4875-2023, 2023
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Benthic foraminifera are single-cell marine organisms which can move in the sediment column. They were previously reported to horizontally and vertically transport sediment particles, yet the impact of their motion on the dissolved fluxes remains unknown. Using microprofiling, we show here that foraminiferal burrow formation increases the oxygen penetration depth in the sediment, leading to a change in the structure of the prokaryotic community.
Masahiko Fujii, Ryuji Hamanoue, Lawrence Patrick Cases Bernardo, Tsuneo Ono, Akihiro Dazai, Shigeyuki Oomoto, Masahide Wakita, and Takehiro Tanaka
Biogeosciences, 20, 4527–4549, https://doi.org/10.5194/bg-20-4527-2023, https://doi.org/10.5194/bg-20-4527-2023, 2023
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This is the first study of the current and future impacts of climate change on Pacific oyster farming in Japan. Future coastal warming and acidification may affect oyster larvae as a result of longer exposure to lower-pH waters. A prolonged spawning period may harm oyster processing by shortening the shipping period and reducing oyster quality. To minimize impacts on Pacific oyster farming, in addition to mitigation measures, local adaptation measures may be required.
Cited articles
Altabet, M. A.: Isotopic tracers of the marine nitrogen cycle: present and
past, in: Marine organic matter: biomarkers, isotopes and DNA, Springer,
251–293, https://doi.org/10.1007/698_2_008, 2006.
Backhaus, J. O.: A three-dimensional model for the simulation of shelf sea
dynamics, Dtsch. Hydrogr. Zetischrift, 38, 165–187, https://doi.org/10.1007/BF02328975, 1985.
Benson, B. B. and Krause Jr., D.: The concentration and isotopic
fractionation of oxygen dissolved in freshwater and seawater in equilibrium
with the atmosphere 1, Limnol. Oceanogr., 29, 620–632, https://doi.org/10.4319/lo.1984.29.3.0620, 1984.
Casciotti, K., Trull, T., Glover, D., and Davies, D.: Constraints on
nitrogen cycling at the subtropical North Pacific Station ALOHA from
isotopic measurements of nitrate and particulate nitrogen, Deep-Sea Res.
Pt. II, 55, 1661–1672, 2008.
Casciotti, K. L., Sigman, D. M., Hastings, M. G., Böhlke, J., and
Hilkert, A.: Measurement of the oxygen isotopic composition of nitrate in
seawater and freshwater using the denitrifier method, Anal. Chem., 74,
4905–4912, https://doi.org/10.1021/ac020113w, 2002.
Casciotti, K. L., Böhlke, J. K., McIlvin, M. R., Mroczkowski, S. J., and
Hannon, J. E.: Oxygen isotopes in nitrite: Analysis, calibration, and
equilibration, Anal. Chem., 79, 2427–2436, https://doi.org/10.1021/ac061598h, 2007.
Casciotti, K. L., Trull, T. W., Glover, D. M., and Davies, D.: Constraints
on nitrogen cycling at the subtropical North Pacific Station ALOHA from
isotopic measurements of nitrate and particulate nitrogen, Deep-Sea Res.
Pt. II, 55, 1661–1672, https://doi.org/10.1016/j.dsr2.2008.04.017, 2008.
Chang, Y., Zhang, Y.-L., Li, J., Tian, C., Song, L., Zhai, X., Zhang, W., Huang, T., Lin, Y.-C., Zhu, C., Fang, Y., Lehmann, M. F., and Chen, J.: Isotopic constraints on the atmospheric sources and formation of nitrogenous species in clouds influenced by biomass burning, Atmos. Chem. Phys., 19, 12221–12234, https://doi.org/10.5194/acp-19-12221-2019, 2019.
Chen, C.-T. A.: Chemical and physical fronts in the Bohai, Yellow and East
China seas, J. Mar. Syst., 78, 394–410, https://doi.org/10.1016/j.jmarsys.2008.11.016, 2009.
Chen, F., Chen, J., Jia, G., Jin, H., Xu, J., Yang, Z., Zhuang, Y., Liu, X.,
and Zhang, H.: Nitrate ä 15N and ä 18O evidence for active
biological transformation in the Changjiang Estuary and the adjacent East
China Sea, Acta Oceanol. Sin., 32, 11–17, https://doi.org/10.1007/s13131-013-0294-4,
2013.
Chen, F., Lao, Q., Zhang, S., Bian, P., Jin, G., Zhu, Q., and Chen, C.:
Nitrate sources and biogeochemical processes identified using nitrogen and
oxygen isotopes on the eastern coast of Hainan Island, Cont. Shelf Res., 207,
104209, https://doi.org/10.1016/j.csr.2020.104209, 2020.
Chen, J., Taniguchi, M., Liu, G., Miyaoka, K., Onodera, S.-I., Tokunaga, T.,
and Fukushima, Y.: Nitrate pollution of groundwater in the Yellow River
delta, China, Hydrogeol. J., 15, 1605–1614, https://doi.org/10.1007/s10040-007-0196-7, 2007.
Copernicus Climate Change Service: ERA5: Fifth generation of ECMWF atmospheric reanalyses of the global climate, Copernicus Climate Change Service Climate Data Store (CDS), https://cds.climate.copernicus.eu/cdsapp#!/home (last access: 30 April 2022), 2017.
Devol, A. H.: Denitrification, Anammox, and N2 Production in Marine
Sediments, Ann. Rev. Mar. Sci., 7, 403–423,
https://doi.org/10.1146/annurev-marine-010213-135040, 2015.
DiFiore, P. J., Sigman, D. M., Trull, T. W., Lourey, M. J., Karsh, K., Cane,
G., and Ho, R.: Nitrogen isotope constraints on subantarctic
biogeochemistry, J. Geophys. Res.-Oean., 111, C08016, https://doi.org/10.1029/2005JC003216, 2006.
DiFiore, P. J., Sigman, D. M., and Dunbar, R. B.: Upper ocean nitrogen
fluxes in the Polar Antarctic Zone: Constraints from the nitrogen and oxygen
isotopes of nitrate, Geochem. Geophy. Geosy., 10, Q11016, https://doi.org/10.1029/2009GC002468, 2009.
Egbert, G. D., and Erofeeva, S. Y.: Efficient inverse modeling of barotropic
ocean tides, J. Atmos. Ocean. Tech., 19, 183–204, https://doi.org/10.1175/1520-0426(2002)019<0183:EIMOBO>2.0.CO;2, 2002.
Emeis, K. C., Mara, P., Schlarbaum, T., Möbius, J., Dähnke, K.,
Struck, U., Mihalopoulos, N., and Krom, M.: External N inputs and internal N
cycling traced by isotope ratios of nitrate, dissolved reduced nitrogen, and
particulate nitrogen in the eastern Mediterranean Sea, J. Geophys.
Res.-Biogeo., 115, G04041, https://doi.org/10.1029/2009JG001214, 2010.
Fan, M.-Y., Zhang, Y.-L., Lin, Y.-C., Chang, Y.-H., Cao, F., Zhang, W.-Q.,
Hu, Y.-B., Bao, M.-Y., Liu, X.-Y., Zhai, X.-Y., Lin, X., Zhao, Z.-Y., and
Song, W.-H.: Isotope-based source apportionment of nitrogen-containing
aerosols: A case study in an industrial city in China, Atmos. Environ., 212,
96–105, https://doi.org/10.1016/j.atmosenv.2019.05.020, 2019.
Fowler, D., Coyle, M., Skiba, U., Sutton, M. A., Cape, J. N., Reis, S., Sheppard, L. J., Jenkins, A., Grizzetti, B., Galloway, J. N., Vitousek, P., Leach, A., Bouwman, A. F., Butterbach-Bahl, K., Dentener, F., Stevenson, D., Amann, M., and Voss, M.: The global nitrogen cycle in the twenty-first century, Philos. T. R. Soc. B, 368, 20130164, https://doi.org/10.1098/rstb.2013.0164, 2013.
Glibert, P. M., Wilkerson, F. P., Dugdale, R. C., Raven, J. A., Dupont, C.
L., Leavitt, P. R., Parker, A. E., Burkholder, J. M., and Kana, T. M.:
Pluses and minuses of ammonium and nitrate uptake and assimilation by
phytoplankton and implications for productivity and community composition,
with emphasis on nitrogen-enriched conditions,
Limnol. Oceanogr., 61, 165–197, https://doi.org/10.1002/lno.10203, 2016.
Granger, J. and Sigman, D. M.: Removal of nitrite with sulfamic acid for
nitrate N and O isotope analysis with the denitrifier method, Rapid Commun.
Mass Spectrom., 23, 3753–3762, https://doi.org/10.1002/rcm.4307, 2009.
Granger, J., Sigman, D. M., Rohde, M., Maldonado, M., and Tortell, P.: N and
O isotope effects during nitrate assimilation by unicellular prokaryotic and
eukaryotic plankton cultures, Geochim. Cosmochim. Ac., 74, 1030–1040,
https://doi.org/10.1016/j.gca.2009.10.044, 2010.
Grasshoff, K., Kremling, K., and Ehrhardt, M.: Methods of seawater analysis,
John Wiley & Sons, Cambridge University Press, https://doi.org/10.1017/S0025315400028216, 2009.
Gu, B., Ju, X., Chang, J., Ge, Y., and Vitousek, P. M.: Integrated reactive
nitrogen budgets and future trends in China, P. Natl. Acad. Sci. USA,
112, 8792, https://doi.org/10.1073/pnas.1510211112, 2015.
Hainbucher, D., Hao, W., Pohlmann, T., Sündermann, J., and Feng, S.:
Variability of the Bohai Sea circulation based on model calculations, J.
Mar. Syst., 44, 153–174, https://doi.org/10.1016/j.jmarsys.2003.09.008, 2004.
Huang, D., Su, J., and Backhaus, J. O.: Modelling the seasonal thermal
stratification and baroclinic circulation in the Bohai Sea, Cont. Shelf
Res., 19, 1485–1505, https://doi.org/10.1016/S0278-4343(99)00026-6, 1999.
IFA: Short-Term Fertilizer Outlook 2019–2020, Versailles, 8, IFA Strategic Forum, https://api.ifastat.org/reports/download/12796 (last access: 30 April 2022), 2019.
Jia, B., and Chen, X. E.: Application of an ice-ocean coupled model to Bohai
Sea ice simulation, J. Oceanol. Limnol., 39, 1–13,
https://doi.org/10.1007/s00343-020-9168-8, 2021.
Kang, D.-J., Chung, C. S., Kim, S. H., Hong, G. H., and Kim, K.-R.: Oxygen
isotope characteristics of seawaters in the Yellow Sea, La Mer, 32, 279–284,
1994.
Kérouel, R. and Aminot, A.: Fluorometric determination of ammonia in
sea and estuarine waters by direct segmented flow analysis, Mar. Chem., 57,
265–275, https://doi.org/10.1016/S0304-4203(97)00040-6, 1997.
Kim, H., Park, G.-H., Lee, S.-E., Kim, Y.-i., Lee, K., Kim, Y.-H., and Kim,
T.-W.: Stable isotope ratio of atmospheric and seawater nitrate in the East
Sea in the northwestern Pacific ocean, Mar. Pollut. Bull., 149, 110610,
https://doi.org/10.1016/j.marpolbul.2019.110610, 2019.
Lehmann, M. F., Sigman, D. M., and Berelson, W. M.: Coupling the 15N
Lellouche, J. M., Legalloudec, O., Regnier, C., Levier, B., Greiner, E., and Drevillon, M.: QUALITY INFORMATION DOCUMENT For Global Sea Physical Analysis and Forecasting Product, GLOBAL_ANALYSIS_FORECAST_PHY_001_024, EU Copernicus Marine Service, https://catalogue.marine.copernicus.eu/documents/QUID/CMEMS-GLO-QUID-001-024.pdf (last access: 30 April 2022), 2019.
Li, Y., Wolanski, E., and Zhang, H.: What processes control the net currents
through shallow straits? A review with application to the Bohai Strait,
China, Estuar. Coast. Shelf Sci., 158, 1–11, https://doi.org/10.1016/j.ecss.2015.03.013, 2015.
Li, Y., Yan, W., Wang, F., Lv, S., Li, Q., and Yu, Q.: Nitrogen pollution
and sources in an aquatic system at an agricultural coastal area of Eastern
China based on a dual-isotope approach, Environ. Sci. Pollut.
Res., 26, 23807–23823, https://doi.org/10.1007/s11356-019-05665-2, 2019.
Li, Z., Walters, W. W., Hastings, M. G., Zhang, Y., Song, L., Liu, D.,
Zhang, W., Pan, Y., Fu, P., and Fang, Y.: Nitrate Isotopic Composition in
Precipitation at a Chinese Megacity: Seasonal Variations, Atmospheric
Processes, and Implications for Sources, Earth Space Sci., 6, 2200–2213, https://doi.org/10.1029/2019EA000759, 2019.
Liu, J., Du, J., and Yi, L.: Ra Tracer-Based Study of Submarine Groundwater
Discharge and Associated Nutrient Fluxes into the Bohai Sea, China: A Highly
Human-Affected Marginal Sea, J. Geophys. Res.-Oean., 122, 8646–8660,
https://doi.org/10.1002/2017JC013095, 2017.
Liu, S., Hong, G.-H., Zhang, J., Ye, X., and Jiang, X.: Nutrient budgets for
large Chinese estuaries, Biogeosciences, 6, 2245–2263, https://doi.org/10.5194/bg-6-2245-2009, 2009.
Liu, S. M., Zhang, J., and Jiang, W. S.: Pore water nutrient regeneration in
shallow coastal Bohai Sea, China, J. Oceanogr., 59, 377–385, https://doi.org/10.1023/A:1025576212927, 2003.
Liu, S. M., Li, L. W., and Zhang, Z.: Inventory of nutrients in the Bohai,
Cont. Shelf Res., 31, 1790–1797, https://doi.org/10.1016/j.csr.2011.08.004, 2011.
Liu, S. M., Altabet, M. A., Zhao, L., Larkum, J., Song, G. D., Zhang, G. L.,
Jin, H., and Han, L. J.: Tracing Nitrogen Biogeochemistry During the
Beginning of a Spring Phytoplankton Bloom in the Yellow Sea Using Coupled
Nitrate Nitrogen and Oxygen Isotope Ratios, J. Geophys. Res.-Biogeo., 122,
2490–2508, https://doi.org/10.1002/2016jg003752, 2017.
Liu, S. M., Ning, X., Dong, S., Song, G., Wang, L., Altabet, M. A., Zhu, Z.,
Wu, Y., Ren, J. L., and Liu, C. G.: Source Versus Recycling Influences on
the Isotopic Composition of Nitrate and Nitrite in the East China Sea, J.
Geophys. Res.-Ocean., 125, e2020JC016061, https://doi.org/10.1029/2020JC016061, 2020.
Lu, C. and Tian, H.: Global nitrogen and phosphorus fertilizer use for agriculture production in the past half century: shifted hot spots and nutrient imbalance, Earth Syst. Sci. Data, 9, 181–192, https://doi.org/10.5194/essd-9-181-2017, 2017.
Luo, X. and Jiao, J. J.: Submarine groundwater discharge and nutrient
loadings in Tolo Harbor, Hong Kong using multiple geotracer-based models,
and their implications of red tide outbreaks, Water Res., 102, 11–31,
https://doi.org/10.1016/j.watres.2016.06.017, 2016.
Ma, S., Xin, F., Cui, Y., and Qiao, X.: Assessment of Main Pollution Matter
Volume into the Sea from Yellow River and Xiaoqing Rive, Prog. Fish.
Sci., 25, 47–51, https://doi.org/10.3969/j.issn.1000-7075.2004.05.009,
2004 (in Chines).
Möbius, J.: Isotope fractionation during nitrogen remineralization
(ammonification): Implications for nitrogen isotope biogeochemistry,
Geochim. Cosmochim. Ac., 105, 422–432, https://doi.org/10.1016/j.gca.2012.11.048, 2013.
Montoya, J. P., Carpenter, E. J., and Capone, D. G.: Nitrogen fixation and
nitrogen isotope abundances in zooplankton of the oligotrophic North
Atlantic, Limnol. Oceanogr., 47, 1617–1628, https://doi.org/10.4319/lo.2002.47.6.1617, 2002.
Müller Schmied, H., Eisner, S., Franz, D., Wattenbach, M., Portmann, F. T., Flörke, M., and Döll, P.: Sensitivity of simulated global-scale freshwater fluxes and storages to input data, hydrological model structure, human water use and calibration, Hydrol. Earth Syst. Sci., 18, 3511–3538, https://doi.org/10.5194/hess-18-3511-2014, 2014.
Murphy, J. and Riley, J. P.: A modified single solution method for the
determination of phosphate in natural waters, Anal. Chim. Acta, 27, 31–36,
1962.
MWR, China: China Water Resources Bulletin, China Water & Power Press, Beijing, http://mwr.gov.cn/sj/tjgb/zghlnsgb/ (last access: 30 April 2022), 2015–2018.
MWR, China: China River Sediment Bulletin 2018, China Water & Power Press, http://mwr.gov.cn/sj/tjgb/zghlnsgb/201906/t20190618_1342326.html (last access: 30 April 2022), 2019.
Ning, X., Lin, C., Su, J., Liu, C., Hao, Q., Le, F., and Tang, Q.: Long-term
environmental changes and the responses of the ecosystems in the Bohai Sea
during 1960–1996, Deep-Sea Res. Pt. II, 57, 1079–1091, https://doi.org/10.1016/j.dsr2.2010.02.010, 2010.
Pätsch, J., Serna, A., Dähnke, K., Schlarbaum, T., Johannsen, A.,
and Emeis, K.-C.: Nitrogen cycling in the German Bight (SE North
Sea)—Clues from modelling stable nitrogen isotopes, Cont. Shelf Res., 30,
203–213, https://doi.org/10.1016/j.csr.2009.11.003, 2010.
Peterson, R. N., Burnett, W. C., Taniguchi, M., Chen, J., Santos, I. R., and
Ishitobi, T.: Radon and radium isotope assessment of submarine groundwater
discharge in the Yellow River delta, China, J. Geophys. Res.-Oean., 113, C09021,
https://doi.org/10.1029/2008JC004776, 2008.
Schlitzer, R.: Ocean Data View, https://odv.awi.de (last access: 30 April 2022), 2021.
Serna, A., Pätsch, J., Dähnke, K., Wiesner, M. G., Hass, H. C.,
Zeiler, M., Hebbeln, D., and Emeis, K.-C.: History of anthropogenic nitrogen
input to the German Bight/SE North Sea as reflected by nitrogen isotopes in
surface sediments, sediment cores and hindcast models, Cont. Shelf Res., 30,
1626–1638, https://doi.org/10.1016/j.csr.2010.06.010, 2010.
Sigman, D. M. and Fripiat, F.: Nitrogen Isotopes in the Ocean, in:
Encyclopedia of Ocean Sciences (Third Edition), edited by: Cochran, J. K.,
Bokuniewicz, H. J., and Yager, P. L., Academic Press, Oxford, 263–278, https://doi.org/10.1016/B978-0-12-409548-9.11605-7, 2019.
Sigman, D. M., Casciotti, K. L., Andreani, M., Barford, C., Galanter, M.,
and Böhlke, J.: A bacterial method for the nitrogen isotopic analysis of
nitrate in seawater and freshwater, Anal. Chem., 73, 4145–4153, https://doi.org/10.1021/ac010088e, 2001.
Sigman, D. M., Granger, J., DiFiore, P. J., Lehmann, M. M., Ho, R., Cane,
G., and van Geen, A.: Coupled nitrogen and oxygen isotope measurements of
nitrate along the eastern North Pacific margin, Global Biogeochem. Cy.,
19, GB4022, https://doi.org/10.1029/2005GB002458, 2005.
Sigman, D. M., DiFiore, P. J., Hain, M. P., Deutsch, C., Wang, Y., Karl, D.
M., Knapp, A. N., Lehmann, M. F., and Pantoja, S.: The dual isotopes of deep
nitrate as a constraint on the cycle and budget of oceanic fixed nitrogen,
Deep-Sea Res. Pt. I, 56, 1419–1439, https://doi.org/10.1016/j.dsr.2009.04.007, 2009.
Smith, S. V., Swaney, D. P., Talaue-Mcmanus, L., Bartley, J. D., Sandhei, P.
T., McLAUGHLIN, C. J., Dupra, V. C., Crossland, C. J., Buddemeier, R. W.,
and Maxwell, B. A.: Humans, hydrology, and the distribution of inorganic
nutrient loading to the ocean, Bioscience, 53, 235–245, https://doi.org/10.1641/0006-3568(2003)053[0235:HHATDO]2.0.CO;2, 2003.
Soares, M.: Biological denitrification of groundwater, Water, Air, Soil
Pollut., 123, 183–193, 2000.
Song, W., Liu, X.-Y., Wang, Y.-L., Tong, Y.-D., Bai, Z.-P., and Liu, C.-Q.:
Nitrogen isotope differences between atmospheric nitrate and corresponding
nitrogen oxides: A new constraint using oxygen isotopes, Sci. Total
Environ., 701, 134515, https://doi.org/10.1016/j.scitotenv.2019.134515, 2020.
Su, J.: A review of circulation dynamics of the coastal oceans near China, Acta Oceanol. Sin., 23, 1–16,
https://doi.org/10.3321/j.issn:0253-4193.2001.04.001, 2001 (in Chinese).
Sugimoto, R., Kasai, A., Miyajima, T., and Fujita, K.: Transport of oceanic
nitrate from the continental shelf to the coastal basin in relation to the
path of the Kuroshio, Cont. Shelf Res., 29, 1678–1688, https://doi.org/10.1016/j.csr.2009.05.013, 2009.
Tan, S. and Shi, G.: Satellite-derived primary productivity and its spatial
and temporal variability in the China seas, J. Geogr.
Sci., 16, 447–457, https://doi.org/10.1007/s11442-006-0408-4, 2006.
Umezawa, Y., Yamaguchi, A., Ishizaka, J., Hasegawa, T., Yoshimizu, C., Tayasu, I., Yoshimura, H., Morii, Y., Aoshima, T., and Yamawaki, N.: Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach, Biogeosciences, 11, 1297–1317, https://doi.org/10.5194/bg-11-1297-2014, 2014.
Wang, J., Yu, Z., Wei, Q., and Yao, Q.: Long-term
nutrient variations in the Bohai Sea over the past 40 years, J. Geophys.
Res.-Oean., 124, 703–722, https://doi.org/10.1029/2018JC014765,
2019.
Wang, W., Yu, Z., Song, X., Wu, Z., Yuan, Y., Zhou, P., and Cao, X.: The
effect of Kuroshio Current on nitrate dynamics in the southern East China
Sea revealed by nitrate isotopic composition, J. Geophys. Res.-Oean., 121,
7073–7087, https://doi.org/10.1002/2016JC011882, 2016.
Wang, W., Yu, Z., Song, X., Wu, Z., Yuan, Y., Zhou, P., and Cao, X.:
Characteristics of the δ15N
Wang, X., Li, H., Jiao, J. J., Barry, D. A., Li, L., Luo, X., Wang, C., Wan,
L., Wang, X., and Jiang, X.: Submarine fresh groundwater discharge into
Laizhou Bay comparable to the Yellow River flux, Sci. Rep.-UK, 5, 8814,
https://doi.org/10.1038/srep08814, 2015.
Wankel, S. D., Kendall, C., Francis, C. A., and Paytan, A.: Nitrogen sources
and cycling in the San Francisco Bay Estuary: A nitrate dual isotopic
composition approach, Limnol. Oceanogr., 51, 1654–1664, https://doi.org/10.4319/lo.2006.51.4.1654, 2006.
Wankel, S. D., Kendall, C., Pennington, J. T., Chavez, F. P., and Paytan,
A.: Nitrification in the euphotic zone as evidenced by nitrate dual isotopic
composition: Observations from Monterey Bay, California, Global Biogeochem.
Cy., 21, GB2009, https://doi.org/10.1029/2006GB002723, 2007.
Wei, H., Zhao, L., and Feng, S.: Annual cycle of phytoplankton biomass and
primary production in the Bohai Sea simulated by a three-dimensional
ecosystem model, Acta Oceanol. Sin., 25, 66–72, 2003 (in Chinese).
Wong, G. T.: Removal of nitrite interference in the Winkler determination of
dissolved oxygen in seawater, Mar. Chem., 130, 28–32, https://doi.org/10.1016/j.marchem.2011.11.003, 2012.
Wu, S.: Oxygen isotope compositions of seawaters in the Huanghai (Yellow)
Sea and the Bohai Sea, Sci. China Ser. B, 34, 327–337,
http://www.cnki.com.cn/Article/CJFDTotal-JBXG199103008.htm (last access: 30 April 2022), 1991.
Wu, Z., Yu, Z., Song, X., Wang, W., Zhou, P., Cao, X., and Yuan, Y.: Key
nitrogen biogeochemical processes in the South Yellow Sea revealed by dual
stable isotopes of nitrate, Estuar. Coast. Shelf Sci., 225, 106222,
https://doi.org/10.1016/j.ecss.2019.05.004, 2019.
Wurl, O.: Practical guidelines for the analysis of seawater, CRC press, ISBN 1420073079,
2009.
Xin, M., Wang, B., Xie, L., Sun, X., Wei, Q., Liang, S., and Chen, K.:
Long-term changes in nutrient regimes and their ecological effects in the
Bohai Sea, China, Mar. Pollut. Bull., 146, 562–573, https://doi.org/10.1016/j.marpolbul.2019.07.011, 2019.
Xu, S., Song, J., Li, X., Yuan, H., Li, N., Duan, L., and Sun, P.: Changes
in nitrogen and phosphorus and their effects on phytoplankton in the Bohai
Sea, China J. Oceanol. Limnol., 28, 945–952, https://doi.org/10.1007/s00343-010-0005-3,
2010.
Yang, Z., Chen, J., Li, H., Jin, H., Gao, S., Ji, Z., Zhu, Y., Ran, L.,
Zhang, J., and Liao, Y.: Sources of nitrate in Xiangshan Bay (China), as
identified using nitrogen and oxygen isotopes, Estuar. Coast. Shelf Sci.,
207, 109–118, https://doi.org/10.1016/j.ecss.2018.02.019, 2018.
Yellow River Conservancy Commission of MWR (China): Yellow River Sediment
Bulletin 2018, in: Yellow River Conservancy Commission of MWR,
China, Zhengzhou, 35 pp., http://www.yrcc.gov.cn/nishagonggao/2018/index.html#p=1 (last access: 30 April 2022), 2019 (in Chinese).
Yu, H., Yu, Z., Song, X., Cao, X., Yuan, Y., and Lu, G.: Seasonal variations
in the nitrogen isotopic composition of dissolved nitrate in the Changjiang
River estuary, China, Estuar. Coast. Shelf Sci., 155, 148–155, https://doi.org/10.1016/j.ecss.2015.01.017, 2015.
Yu, J., Zhang, W., Tan, Y., Zong, Z., Hao, Q., Tian, C., Zhang, H., Li, J.,
Fang, Y., and Zhang, G.: Dual-isotope-based source apportionment of nitrate
in 30 rivers draining into the Bohai Sea, north China, Environ. Pollut.,
283, 117112, https://doi.org/10.1016/j.envpol.2021.117112,
2021.
Yu, Q., Lou, A., Zhang, X., and Li, N.: Numerical Analysis on the Impact of
Main River Runoff on the Plain Distribution in the Low-Salinity Area at
North Liaodong Bay, Trans. Oceanol. Limnol., 2,
88–96, https://doi.org/10.13984/j.cnki.cn37-1141.2018.02.012, 2018 (in Chinese).
Yue, F.-J., Li, S.-L., Liu, C.-Q., Zhao, Z.-Q., and Hu, J.: Using dual
isotopes to evaluate sources and transformation of nitrogen in the Liao
River, northeast China, Appl. Geochem., 36, 1–9, https://doi.org/10.1016/j.apgeochem.2013.06.009, 2013.
Zhang, G., Zhang, J., and Liu, S.: Characterization of nutrients in the
atmospheric wet and dry deposition observed at the two monitoring sites over
Yellow Sea and East China Sea, J. Atmos. Chem., 57, 41–57,
https://doi.org/10.1007/s10874-007-9060-3, 2007.
Zhang, J., Yu, Z., Raabe, T., Liu, S., Starke, A., Zou, L., Gao, H., and
Brockmann, U.: Dynamics of inorganic nutrient species in the Bohai
seawaters, J. Mar. Syst., 44, 189–212, https://doi.org/10.1016/j.jmarsys.2003.09.010, 2004.
Zhang, L., Song, L., Zhang, L., Shao, H., Chen, X., and Yan, K.: Seasonal
dynamics in nitrous oxide emissions under different types of vegetation in
saline-alkaline soils of the Yellow River Delta, China and implications for
eco-restoring coastal wetland, Ecol. Eng., 61, 82–89, https://doi.org/10.1016/j.ecoleng.2013.09.065, 2013.
Zhang, X., Zhang, Q., Yang, A., Hou, L., Zheng, Y., Zhai, W., and Gong, J.:
Incorporation of Microbial Functional Traits in Biogeochemistry Models
Provides Better Estimations of Benthic Denitrification and Anammox Rates in
Coastal Oceans, J. Geophys. Res.-Biogeo., 123, 3331–3352, https://doi.org/10.1029/2018JG004682, 2018.
Zhang, Y., Liu, X., Fangmeier, A., Goulding, K., and Zhang, F.: Nitrogen
inputs and isotopes in precipitation in the North China Plain, Atmos.
Environ., 42, 1436–1448, https://doi.org/10.1016/j.atmosenv.2007.11.002, 2008.
Zhang, Z., Zheng, N., Zhang, D., Xiao, H., Cao, Y., and Xiao, H.: Rayleigh
based concept to track NOx emission sources in urban areas of China, Sci.
Total Environ., 704, 135362, https://doi.org/10.1016/j.scitotenv.2019.135362, 2019.
Zhao, L., Wei, H., and Feng S.: Annual Cycle and Budgets of Nutrients in the Bohai Sea, Chinese J. Environ. Sci., 1, 29–37, https://en.cnki.com.cn/Article_en/CJFDTotal-QDHB200201006.htm, 2002
Zhao, Y., Zhang, L., Chen, Y., Liu, X., Xu, W., Pan, Y., and Duan, L.:
Atmospheric nitrogen deposition to China: A model analysis on nitrogen
budget and critical load exceedance, Atmos. Environ., 153, 32–40, https://doi.org/10.1016/j.atmosenv.2017.01.018, 2017.
Zong, Z., Wang, X., Tian, C., Chen, Y., Fang, Y., Zhang, F., Li, C., Sun,
J., Li, J., and Zhang, G.: First Assessment of NOx Sources at a Regional
Background Site in North China Using Isotopic Analysis Linked with Modeling,
Environ. Sci. Technol., 51, 5923–5931, https://doi.org/10.1021/acs.est.6b06316, 2017.
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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