Articles | Volume 20, issue 5
https://doi.org/10.5194/os-20-1423-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-20-1423-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
30 Oct 2024
Research article |
| 30 Oct 2024
| 30 Oct 2024
Alkalinity sources in the Dutch Wadden Sea
Mona Norbisrath
CORRESPONDING AUTHOR
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, 21502 Geesthacht, Germany
Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany
now at: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
Justus E. E. van Beusekom
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, 21502 Geesthacht, Germany
Helmuth Thomas
Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, 21502 Geesthacht, Germany
Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany
Related authors
Mona Norbisrath, Andreas Neumann, Kirstin Dähnke, Tina Sanders, Andreas Schöl, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 20, 4307–4321, https://doi.org/10.5194/bg-20-4307-2023, https://doi.org/10.5194/bg-20-4307-2023, 2023
Short summary
Short summary
Total alkalinity (TA) is the oceanic capacity to store CO2. Estuaries can be a TA source. Anaerobic metabolic pathways like denitrification (reduction of NO3− to N2) generate TA and are a major nitrogen (N) sink. Another important N sink is anammox that transforms NH4+ with NO2− into N2 without TA generation. By combining TA and N2 production, we identified a TA source, denitrification, occurring in the water column and suggest anammox as the dominant N2 producer in the bottom layer of the Ems.
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
Short summary
Short summary
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.
Claudia Elena Schmidt, Tristan Zimmermann, Katarzyna Koziorowska, Daniel Pröfrock, and Helmuth Thomas
EGUsphere, https://doi.org/10.5194/egusphere-2025-291, https://doi.org/10.5194/egusphere-2025-291, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
Short summary
Short summary
This study explores how ocean currents, melting sea ice, and freshwater runoff alter biogeochemical cycles on the west Greenland shelf. By analyzing water samples on a high-resolution, large-scale grid, we found that these factors create distinct regional and spatial distribution patterns and significantly impact biological productivity during late summer. The study highlights the need for ongoing monitoring to understand the effects of climate change in this sensitive area.
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
Short summary
Short summary
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.
Kubilay Timur Demir, Moritz Mathis, Jan Kossack, Feifei Liu, Ute Daewel, Christoph Stegert, Helmuth Thomas, and Corinna Schrum
EGUsphere, https://doi.org/10.5194/egusphere-2024-3449, https://doi.org/10.5194/egusphere-2024-3449, 2024
Short summary
Short summary
This study examines how variations in the ratios of carbon, nitrogen and phosphorus in organic matter affect carbon cycling in the Northwest European shelf seas. Traditional models with fixed ratios tend to underestimate biological carbon uptake. By integrating variable ratios into a regional model, we find that carbon dioxide uptake increases by 10–33 %. These results highlight the need to include variable ratios for accurate assessments of regional and global carbon cycles.
Julia Meyer, Yoana G. Voynova, Bryce Van Dam, Lara Luitjens, Dagmar Daehne, and Helmuth Thomas
EGUsphere, https://doi.org/10.5194/egusphere-2024-3048, https://doi.org/10.5194/egusphere-2024-3048, 2024
Short summary
Short summary
The study highlights the inter-seasonal variability of the carbonate dynamics of the East Frisian Wadden Sea, the world's largest intertidal area. During spring, increased biological activity leads to lower CO2 and nitrate levels, while total alkalinity (TA) rises slightly. In summer, TA increases, enhancing the ocean's ability to absorb CO2. Our research emphasizes the vital role of these intertidal regions in regulating carbon, contributing to a better understanding of carbon storage.
Louise C. V. Rewrie, Burkard Baschek, Justus E. E. van Beusekom, Arne Körtzinger, Gregor Ollesch, and Yoana G. Voynova
Biogeosciences, 20, 4931–4947, https://doi.org/10.5194/bg-20-4931-2023, https://doi.org/10.5194/bg-20-4931-2023, 2023
Short summary
Short summary
After heavy pollution in the 1980s, a long-term inorganic carbon increase in the Elbe Estuary (1997–2020) was fueled by phytoplankton and organic carbon production in the upper estuary, associated with improved water quality. A recent drought (2014–2020) modulated the trend, extending the water residence time and the dry summer season into May. The drought enhanced production of inorganic carbon in the estuary but significantly decreased the annual inorganic carbon export to coastal waters.
Mona Norbisrath, Andreas Neumann, Kirstin Dähnke, Tina Sanders, Andreas Schöl, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 20, 4307–4321, https://doi.org/10.5194/bg-20-4307-2023, https://doi.org/10.5194/bg-20-4307-2023, 2023
Short summary
Short summary
Total alkalinity (TA) is the oceanic capacity to store CO2. Estuaries can be a TA source. Anaerobic metabolic pathways like denitrification (reduction of NO3− to N2) generate TA and are a major nitrogen (N) sink. Another important N sink is anammox that transforms NH4+ with NO2− into N2 without TA generation. By combining TA and N2 production, we identified a TA source, denitrification, occurring in the water column and suggest anammox as the dominant N2 producer in the bottom layer of the Ems.
Nele Lehmann, Hugues Lantuit, Michael Ernst Böttcher, Jens Hartmann, Antje Eulenburg, and Helmuth Thomas
Biogeosciences, 20, 3459–3479, https://doi.org/10.5194/bg-20-3459-2023, https://doi.org/10.5194/bg-20-3459-2023, 2023
Short summary
Short summary
Riverine alkalinity in the silicate-dominated headwater catchment at subarctic Iskorasfjellet, northern Norway, was almost entirely derived from weathering of minor carbonate occurrences in the riparian zone. The uphill catchment appeared limited by insufficient contact time of weathering agents and weatherable material. Further, alkalinity increased with decreasing permafrost extent. Thus, with climate change, alkalinity generation is expected to increase in this permafrost-degrading landscape.
Johannes J. Rick, Mirco Scharfe, Tatyana Romanova, Justus E. E. van Beusekom, Ragnhild Asmus, Harald Asmus, Finn Mielck, Anja Kamp, Rainer Sieger, and Karen H. Wiltshire
Earth Syst. Sci. Data, 15, 1037–1057, https://doi.org/10.5194/essd-15-1037-2023, https://doi.org/10.5194/essd-15-1037-2023, 2023
Short summary
Short summary
The Sylt Roads (Wadden Sea) time series is illustrated. Since 1984, the water temperature has risen by 1.1 °C, while pH and salinity decreased by 0.2 and 0.3 units. Nutrients (P, N) displayed a period of high eutrophication until 1998 and have decreased since 1999, while Si showed a parallel increase. Chlorophyll did not mirror these changes, probably due to a switch in nutrient limitation. Until 1998, algae were primarily limited by Si, and since 1999, P limitation has become more important.
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
Short summary
Short summary
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.
Bryce Van Dam, Nele Lehmann, Mary A. Zeller, Andreas Neumann, Daniel Pröfrock, Marko Lipka, Helmuth Thomas, and Michael Ernst Böttcher
Biogeosciences, 19, 3775–3789, https://doi.org/10.5194/bg-19-3775-2022, https://doi.org/10.5194/bg-19-3775-2022, 2022
Short summary
Short summary
We quantified sediment–water exchange at shallow sites in the North and Baltic seas. We found that porewater irrigation rates in the former were approximately twice as high as previously estimated, likely driven by relatively high bioirrigative activity. In contrast, we found small net fluxes of alkalinity, ranging from −35 µmol m−2 h−1 (uptake) to 53 µmol m−2 h−1 (release). We attribute this to low net denitrification, carbonate mineral (re-)precipitation, and sulfide (re-)oxidation.
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
Short summary
Short summary
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.
Krysten Rutherford, Katja Fennel, Dariia Atamanchuk, Douglas Wallace, and Helmuth Thomas
Biogeosciences, 18, 6271–6286, https://doi.org/10.5194/bg-18-6271-2021, https://doi.org/10.5194/bg-18-6271-2021, 2021
Short summary
Short summary
Using a regional model of the northwestern North Atlantic shelves in combination with a surface water time series and repeat transect observations, we investigate surface CO2 variability on the Scotian Shelf. The study highlights a strong seasonal cycle in shelf-wide pCO2 and spatial variability throughout the summer months driven by physical events. The simulated net flux of CO2 on the Scotian Shelf is out of the ocean, deviating from the global air–sea CO2 flux trend in continental shelves.
Onur Kerimoglu, Yoana G. Voynova, Fatemeh Chegini, Holger Brix, Ulrich Callies, Richard Hofmeister, Knut Klingbeil, Corinna Schrum, and Justus E. E. van Beusekom
Biogeosciences, 17, 5097–5127, https://doi.org/10.5194/bg-17-5097-2020, https://doi.org/10.5194/bg-17-5097-2020, 2020
Short summary
Short summary
In this study, using extensive field observations and a numerical model, we analyzed the physical and biogeochemical structure of a coastal system following an extreme flood event. Our results suggest that a number of anomalous observations were driven by a co-occurrence of peculiar meteorological conditions and increased riverine discharges. Our results call for attention to the combined effects of hydrological and meteorological extremes that are anticipated to increase in frequency.
Chantal Mears, Helmuth Thomas, Paul B. Henderson, Matthew A. Charette, Hugh MacIntyre, Frank Dehairs, Christophe Monnin, and Alfonso Mucci
Biogeosciences, 17, 4937–4959, https://doi.org/10.5194/bg-17-4937-2020, https://doi.org/10.5194/bg-17-4937-2020, 2020
Short summary
Short summary
Major research initiatives have been undertaken within the Arctic Ocean, highlighting this area's global importance and vulnerability to climate change. In 2015, the international GEOTRACES program addressed this importance by devoting intense research activities to the Arctic Ocean. Among various tracers, we used radium and carbonate system data to elucidate the functioning and vulnerability of the hydrographic regime of the Canadian Arctic Archipelago, bridging the Pacific and Atlantic oceans.
Fabian Schwichtenberg, Johannes Pätsch, Michael Ernst Böttcher, Helmuth Thomas, Vera Winde, and Kay-Christian Emeis
Biogeosciences, 17, 4223–4245, https://doi.org/10.5194/bg-17-4223-2020, https://doi.org/10.5194/bg-17-4223-2020, 2020
Short summary
Short summary
Ocean acidification has a range of potentially harmful consequences for marine organisms. It is related to total alkalinity (TA) mainly produced in oxygen-poor situations like sediments in tidal flats. TA reduces the sensitivity of a water body to acidification. The decomposition of organic material and subsequent TA release in the tidal areas of the North Sea (Wadden Sea) is responsible for reduced acidification in the southern North Sea. This is shown with the results of an ecosystem model.
Alexis Beaupré-Laperrière, Alfonso Mucci, and Helmuth Thomas
Biogeosciences, 17, 3923–3942, https://doi.org/10.5194/bg-17-3923-2020, https://doi.org/10.5194/bg-17-3923-2020, 2020
Short summary
Short summary
Ocean acidification is the process by which the oceans are changing due to carbon dioxide emissions from human activities. Studying this process in the Arctic Ocean is essential as this ocean and its ecosystems are more vulnerable to the effects of acidification. Water chemistry measurements made in recent years show that waters in and around the Canadian Arctic Archipelago are considerably affected by this process and show dynamic conditions that might have an impact on local marine organisms.
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
Short summary
Short summary
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.
Louise Delaigue, Helmuth Thomas, and Alfonso Mucci
Biogeosciences, 17, 547–566, https://doi.org/10.5194/bg-17-547-2020, https://doi.org/10.5194/bg-17-547-2020, 2020
Short summary
Short summary
This paper reports on the first compilation and analysis of the surface water pCO2 distribution in the Saguenay Fjord, the southernmost subarctic fjord in the Northern Hemisphere, and thus fills a significant knowledge gap in current regional estimates of estuarine CO2 emissions.
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
Short summary
Short summary
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.
Rachel M. Horwitz, Alex E. Hay, William J. Burt, Richard A. Cheel, Joseph Salisbury, and Helmuth Thomas
Biogeosciences, 16, 605–616, https://doi.org/10.5194/bg-16-605-2019, https://doi.org/10.5194/bg-16-605-2019, 2019
Short summary
Short summary
High-frequency CO2 measurements are used to quantify the daily and tidal cycles of dissolved carbon in the Bay of Fundy – home to the world's largest tides. The oscillating tidal flows drive a net carbon transport, and these results suggest that previously unaccounted for tidal variation could substantially modulate the coastal ocean's response to global ocean acidification. Evaluating the impact of rising atmospheric CO2 on coastal systems requires understanding this short-term variability.
Jonathan Lemay, Helmuth Thomas, Susanne E. Craig, William J. Burt, Katja Fennel, and Blair J. W. Greenan
Biogeosciences, 15, 2111–2123, https://doi.org/10.5194/bg-15-2111-2018, https://doi.org/10.5194/bg-15-2111-2018, 2018
Short summary
Short summary
We report a detailed mechanistic investigation of the impact of Hurricane Arthur on the CO2 cycling on the Scotian Shelf. We can show that in contrast to common thinking, the deepening of the surface during the summer months can lead to increased CO2 uptake as carbon-poor waters from subsurface water are brought up to the surface. Only during prolonged storm events is the deepening of the mixed layer strong enough to bring the (expected) carbon-rich water to the surface.
Jacoba Mol, Helmuth Thomas, Paul G. Myers, Xianmin Hu, and Alfonso Mucci
Biogeosciences, 15, 1011–1027, https://doi.org/10.5194/bg-15-1011-2018, https://doi.org/10.5194/bg-15-1011-2018, 2018
Short summary
Short summary
In the fall of 2014, the upwelling of water from the deep Canada Basin brought water onto the shallower Mackenzie Shelf in the Beaufort Sea. This increased the concentration of CO2 in water on the shelf, which alters pH and changes the transfer of CO2 between the ocean and atmosphere. These findings were a combined result of water sampling for CO2 parameters and the use of a computer model that simulates water movement in the ocean.
Tom J. S. Cox, Justus E. E. van Beusekom, and Karline Soetaert
Biogeosciences, 14, 5271–5280, https://doi.org/10.5194/bg-14-5271-2017, https://doi.org/10.5194/bg-14-5271-2017, 2017
Short summary
Short summary
Photosynthesis by phytoplankton is a key source of oxygen (O2) in aquatic systems. We have developed a mathematical technique to calculate the rate of photosynthesis from time series of O2. Additionally, the approach leads to a better understanding of the influence on O2 measurements of the tides in coasts and estuaries. The results are important for correctly interpreting the data that are gathered by a growing set of continuous O2 sensors that are deployed around the world.
Rachel Hussherr, Maurice Levasseur, Martine Lizotte, Jean-Éric Tremblay, Jacoba Mol, Helmuth Thomas, Michel Gosselin, Michel Starr, Lisa A. Miller, Tereza Jarniková, Nina Schuback, and Alfonso Mucci
Biogeosciences, 14, 2407–2427, https://doi.org/10.5194/bg-14-2407-2017, https://doi.org/10.5194/bg-14-2407-2017, 2017
Short summary
Short summary
This study assesses the impact of ocean acidification on phytoplankton and its synthesis of the climate-active gas dimethyl sulfide (DMS), as well as its modulation, by two contrasting light regimes in the Arctic. The light regimes tested had no significant impact on either the phytoplankton or DMS concentration, whereas both variables decreased linearly with the decrease in pH. Thus, a rapid decrease in surface water pH could alter the algal biomass and inhibit DMS production in the Arctic.
William J. Burt, Helmuth Thomas, Lisa A. Miller, Mats A. Granskog, Tim N. Papakyriakou, and Leah Pengelly
Biogeosciences, 13, 4659–4671, https://doi.org/10.5194/bg-13-4659-2016, https://doi.org/10.5194/bg-13-4659-2016, 2016
Short summary
Short summary
This study assesses the state of the carbon cycle in Hudson Bay, an ecologically important region of the Canadian Arctic. Results show that river input, sea-ice melt, biological activity, and general circulation patterns all have significant, and regionally dependent, impacts on the carbon cycle. The study also highlights the importance of detailed sampling procedures in highly stratified waters, and reveals that the deep Hudson Bay is primarily filled with waters of Pacific origin.
Fabian Große, Naomi Greenwood, Markus Kreus, Hermann-Josef Lenhart, Detlev Machoczek, Johannes Pätsch, Lesley Salt, and Helmuth Thomas
Biogeosciences, 13, 2511–2535, https://doi.org/10.5194/bg-13-2511-2016, https://doi.org/10.5194/bg-13-2511-2016, 2016
Short summary
Short summary
We used the ECOHAM5 model to provide a consistent picture of the physical and biological drivers of oxygen deficiency in the North Sea. Regions susceptible to oxygen deficiency are characterised by low tidal mixing and moderate water depth (~ 40 m). Variations in upper layer productivity drive the year-to-year variability of bottom oxygen conditions. The model-based analysis reveals that benthic and pelagic remineralisation account for 90 % of bottom oxygen consumption observed at North Dogger.
N. Jiao, C. Robinson, F. Azam, H. Thomas, F. Baltar, H. Dang, N. J. Hardman-Mountford, M. Johnson, D. L. Kirchman, B. P. Koch, L. Legendre, C. Li, J. Liu, T. Luo, Y.-W. Luo, A. Mitra, A. Romanou, K. Tang, X. Wang, C. Zhang, and R. Zhang
Biogeosciences, 11, 5285–5306, https://doi.org/10.5194/bg-11-5285-2014, https://doi.org/10.5194/bg-11-5285-2014, 2014
A. Canion, J. E. Kostka, T. M. Gihring, M. Huettel, J. E. E. van Beusekom, H. Gao, G. Lavik, and M. M. M. Kuypers
Biogeosciences, 11, 309–320, https://doi.org/10.5194/bg-11-309-2014, https://doi.org/10.5194/bg-11-309-2014, 2014
S. E. Craig, H. Thomas, C. T. Jones, W. K. W. Li, B. J. W. Greenan, E. H. Shadwick, and W. J. Burt
Biogeosciences Discuss., https://doi.org/10.5194/bgd-10-11255-2013, https://doi.org/10.5194/bgd-10-11255-2013, 2013
Revised manuscript not accepted
W. J. Burt, H. Thomas, K. Fennel, and E. Horne
Biogeosciences, 10, 53–66, https://doi.org/10.5194/bg-10-53-2013, https://doi.org/10.5194/bg-10-53-2013, 2013
Related subject area
Approach: In situ Observations | Properties and processes: Biogeochemistry and nutrient cycles
Control of spatio-temporal variability of ocean nutrients in the East Australian Current
Anthropogenic CO2, air–sea CO2 fluxes, and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51° S–68° E)
Megan Jeffers, Christopher C. Chapman, Bernadette M. Sloyan, and Helen Bostock
Ocean Sci., 21, 537–554, https://doi.org/10.5194/os-21-537-2025, https://doi.org/10.5194/os-21-537-2025, 2025
Short summary
Short summary
This study analyses physical and biogeochemical data collected in the East Australian Current (EAC) to understand variability in the nutrient-poor surface waters. The distribution of nutrients in the water column is influenced by seasonal flow and the EAC's position. An inshore EAC has a deeper nutricline and lower nutrient concentrations compared to an offshore EAC position. This has implications for the marine ecosystems along the coastline.
Nicolas Metzl, Claire Lo Monaco, Coraline Leseurre, Céline Ridame, Gilles Reverdin, Thi Tuyet Trang Chau, Frédéric Chevallier, and Marion Gehlen
Ocean Sci., 20, 725–758, https://doi.org/10.5194/os-20-725-2024, https://doi.org/10.5194/os-20-725-2024, 2024
Short summary
Short summary
In the southern Indian Ocean, south of the polar front, an observed increase of sea surface fCO2 and a decrease of pH over 1985–2021 are mainly driven by anthropogenic CO2 uptake, but in the last decade (2010–2020) fCO2 and pH were stable in summer, highlighting the competitive balance between anthropogenic CO2 and primary production. In the water column the increase of anthropogenic CO2 concentrations leads to migration of the aragonite saturation state from 600 m in 1985 up to 400 m in 2021.
Cited articles
Abril, G. and Frankignoulle, M.: Nitrogen–alkalinity interactions in the highly polluted Scheldt basin (Belgium), Water Res., 35, 844–850, https://doi.org/10.1016/S0043-1354(00)00310-9, 2001.
Beck, M., Dellwig, O., Holstein, J. M., Grunwald, M., Liebezeit, G., Schnetger, B., and Brumsack, H.-J.: Sulphate, dissolved organic carbon, nutrients and terminal metabolic products in deep pore waters of an intertidal flat, Biogeochemistry, 89, 221–238, https://doi.org/10.1007/s10533-008-9215-6, 2008a.
Beck, M., Dellwig, O., Liebezeit, G., Schnetger, B., and Brumsack, H.-J.: Spatial and seasonal variations of sulphate, dissolved organic carbon, and nutrients in deep pore waters of intertidal flat sediments, Estuar. Coast. Shelf S., 79, 307–316, https://doi.org/10.1016/j.ecss.2008.04.007, 2008b.
Berner, R. A., Scott, M. R., and Thomlinson, C.: Carbonate alkalinity in the pore waters of anoxic marine sediments, Limnol. Oceanogr., 15, 544–549, https://doi.org/10.4319/lo.1970.15.4.0544, 1970.
Berner, R. A., Lasaga, A. C., and Garrels, R. M.: Carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years, Am. J. Sci., 283, 641–683, https://doi.org/10.2475/ajs.283.7.641, 1983.
Billerbeck, M., Werner, U., Polerecky, L., Walpersdorf, E., DeBeer, D., and Huettel, M.: Surficial and deep pore water circulation governs spatial and temporal scales of nutrient recycling in intertidal sand flat sediment, Mar. Ecol. Prog. Ser., 326, 61–76, 2006.
Borges, A. V., Delille, B., and Frankignoulle, M.: Budgeting sinks and sources of CO2 in the coastal ocean: Diversity of ecosystems counts, Geophys. Res. Lett., 32, L14601, https://doi.org/10.1029/2005GL023053, 2005.
Bozec, Y., Thomas, H., Elkalay, K., and de Baar, H. J.: The continental shelf pump for CO2 in the North Sea – evidence from summer observation, Mar. Chem., 93, 131–147, https://doi.org/10.1016/j.marchem.2004.07.006, 2005.
Brasse, S., Reimer, A., Seifert, R., and Michaelis, W.: The influence of intertidal mudflats on the dissolved inorganic carbon and total alkalinity distribution in the German Bight, southeastern North Sea, J. Sea Res., 42, 93–103, 1999.
Brenner, H., Braeckman, U., Le Guitton, M., and Meysman, F. J. R.: The impact of sedimentary alkalinity release on the water column CO2 system in the North Sea, Biogeosciences, 13, 841–863, https://doi.org/10.5194/bg-13-841-2016, 2016.
Brewer, P. G. and Goldman, J. C.: Alkalinity changes generated by phytoplankton growth, Limnol. Oceanogr., 21, 108–117, https://doi.org/10.4319/lo.1976.21.1.0108, 1976.
Brzezinski, M. A.: The
Burchard, H., Flöser, G., Staneva, J. V., Badewien, T. H., and Riethmüller, R.: Impact of density gradients on net sediment transport into the Wadden Sea, J. Phys. Oceanogr., 38, 566–587, 2008.
Burt, W., Thomas, H., Hagens, M., Pätsch, J., Clargo, N., Salt, L., Winde, V., and Böttcher, M.: Carbon sources in the North Sea evaluated by means of radium and stable carbon isotope tracers, Limnol. Oceanogr., 61, 666–683, https://doi.org/10.1002/lno.10243, 2016.
Carter, B. R., Toggweiler, J. R., Key, R. M., and Sarmiento, J. L.: Processes determining the marine alkalinity and calcium carbonate saturation state distributions, Biogeosciences, 11, 7349–7362, https://doi.org/10.5194/bg-11-7349-2014, 2014.
Charalampopoulou, A., Poulton, A. J., Tyrrell, T., and Lucas, M. I.: Irradiance and pH affect coccolithophore community composition on a transect between the North Sea and the Arctic Ocean, Mar. Ecol. Prog. Ser., 431, 25–43, https://doi.org/10.3354/meps09140, 2011.
Chen, C. T. A. and Wang, S. L.: Carbon, alkalinity and nutrient budgets on the East China Sea continental shelf, J. Geophys. Res.-Oceans, 104, 20675–20686, https://doi.org/10.1029/1999JC900055, 1999.
Crutzen, P.: Geology of mankind, Nature, 415, 23, https://doi.org/10.1038/415023a, 2002.
De Beer, D., Wenzhöfer, F., Ferdelman, T. G., Boehme, S. E., Huettel, M., van Beusekom, J. E., Böttcher, M. E., Musat, N., and Dubilier, N.: Transport and mineralization rates in North Sea sandy intertidal sediments, Sylt-Rømø basin, Wadden Sea, Limnol. Oceanogr., 50, 113–127, 2005.
De Jonge, V., Essink, K., and Boddeke, R.: The Dutch Wadden Sea: a changed ecosystem, Hydrobiologia, 265, 45–71, https://doi.org/10.1007/BF00007262, 1993.
Dickson, A. and Millero, F. J.: A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media, Deep-Sea Res., 34, 1733–1743, https://doi.org/10.1016/0198-0149(87)90021-5, 1987.
Dickson, A. G.: An exact definition of total alkalinity and a procedure for the estimation of alkalinity and total inorganic carbon from titration data, Deep-Sea Res., 28, 609–623, https://doi.org/10.1016/0198-0149(81)90121-7, 1981.
Duran-Matute, M., Gerkema, T., de Boer, G. J., Nauw, J. J., and Gräwe, U.: Residual circulation and freshwater transport in the Dutch Wadden Sea: a numerical modelling study, Ocean Sci., 10, 611–632, https://doi.org/10.5194/os-10-611-2014, 2014.
Elias, E. P., Van der Spek, A. J., Wang, Z. B., and De Ronde, J.: Morphodynamic development and sediment budget of the Dutch Wadden Sea over the last century, Neth. J. Geosci., 91, 293–310, https://doi.org/10.1017/S0016774600000457, 2012.
Faber, P. A., Evrard, V., Woodland, R. J., Cartwright, I. C., and Cook, P. L.: Pore-water exchange driven by tidal pumping causes alkalinity export in two intertidal inlets, Limnol. Oceanogr., 59, 1749–1763, https://doi.org/10.4319/lo.2014.59.5.1749, 2014.
Glavovic, B., Limburg, K., Liu, K., Emeis, K., Thomas, H., Kremer, H., Avril, B., Zhang, J., Mulholland, M., and Glaser, M.: Living on the Margin in the Anthropocene: engagement arenas for sustainability research and action at the ocean–land interface, Curr. Opin. Env. Sust., 14, 232–238, https://doi.org/10.1016/j.cosust.2015.06.003, 2015.
Grasshoff, K., Kremling, K., and Ehrhardt, M.: Methods of seawater analysis, John Wiley & Sons, ISBN 978-3-527-61399-1, 2009.
Hansen, H. and Koroleff, F.: Determination of nutrients. Methods of Seawater Analysis: Third, Completely Revised and Extended Edition, edited by: Grasshoff, K., Kremling, K., and Ehrhardt, M., Wiley-VCH Verlag GmbH, Weinheim, Germany, https://doi.org/10.1002/9783527613984.ch10, 2007.
Hickel, W.: Seston in the Wadden Sea of Sylt (German Bight, North Sea), Netherlands Institute for Sea Research – Publication Series, 10, 113–131, 1984.
Hoppema, J.: The distribution and seasonal variation of alkalinity in the southern bight of the North Sea and in the western Wadden Sea, Neth. J. Sea Res., 26, 11–23, https://doi.org/10.1016/0077-7579(90)90053-J, 1990.
Hoppema, J.: The oxygen budget of the western Wadden Sea, The Netherlands, Estuar. Coast. Shelf S., 32, 483–502, https://doi.org/10.1016/0272-7714(91)90036-B, 1991.
Hoppema, J.: Carbon dioxide and oxygen disequilibrium in a tidal basin (Dutch Wadden Sea), Neth. J. Sea Res., 31, 221–229, https://doi.org/10.1016/0077-7579(93)90023-L, 1993.
Hu, X. and Cai, W. J.: An assessment of ocean margin anaerobic processes on oceanic alkalinity budget, Global Biogeochem. Cy., 25, GB3003, https://doi.org/10.1029/2010GB003859, 2011.
Huettel, M., Røy, H., Precht, E., and Ehrenhauss, S.: Hydrodynamical impact on biogeochemical processes in aquatic sediments, in: The Interactions between Sediments and Water. Developments in Hydrobiology, edited by: Kronvang, B., vol. 169, Springer, Dordrecht, https://doi.org/10.1007/978-94-017-3366-3_31, 2003.
Jahnke, R. A., Craven, D. B., and Gaillard, J.-F.: The influence of organic matter diagenesis on CaCO3 dissolution at the deep-sea floor, Geochim. Cosmochim. Ac., 58, 2799–2809, 1994.
Jensen, K., Jensen, M., and Kristensen, E.: Nitrification and denitrification in Wadden Sea sediments (Königshafen, Island of Sylt, Germany) as measured by nitrogen isotope pairing and isotope dilution, Aquat. Microb. Ecol., 11, 181–191, https://doi.org/10.3354/ame011181, 1996.
Keith, D. W., Ha-Duong, M., and Stolaroff, J. K.: Climate strategy with CO2 capture from the air, Climatic Change, 74, 17–45, https://doi.org/10.1007/s10584-005-9026-x, 2006.
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.
Kieskamp, W. M., Lohse, L., Epping, E., and Helder, W.: Seasonal variation in denitrification rates and nitrous oxide fluxes in intertidal sediments of the western Wadden Sea, Mar. Ecol. Prog. Ser., 72, 145–151, 1991.
Legendre, P.: lmodel2: Model II Regression, R package version 1.7-3, https://CRAN.R-project.org/package=lmodel2 (last access: 18 October 2024), 2018.
Lewis, E. R. and Wallace, D. W. R.: Program Developed for CO2 System Calculations, United States, https://doi.org/10.15485/1464255, 1998.
Louters, T. and Gerritsen, F.: The Riddle of the Sands: A Tidal SystenVs Answer to a Rising Sea Level, report RIKZ-94.040, National Institute for Coastal and Marine management (RIKZ), ISBN 90-369-0084-0, 1994.
Marx, A., Dusek, J., Jankovec, J., Sanda, M., Vogel, T., van Geldern, R., Hartmann, J., and Barth, J. A. C.: A review of CO2 and associated carbon dynamics in headwater streams: A global perspective, Rev. Geophys., 55, 560-585, https://doi.org/10.1002/2016RG000547, 2017.
Matthews, H. D. and Caldeira, K.: Stabilizing climate requires near-zero emissions, Geophys. Res. Lett., 35, L04705, https://doi.org/10.1029/2007GL032388, 2008.
Mehrbach, C., Culberson, C., Hawley, J., and Pytkowicx, R.: Measurement of the apparent dissociation constants of carbonic acid in seawater at atmospheric pressure, Limnol. Oceanogr., 18, 897–907, https://doi.org/10.4319/lo.1973.18.6.0897, 1973.
Meybeck, M.: Global chemical weathering of surficial rocks estimated from river dissolved loads, Am. J. Sci., 287, 401–428, https://doi.org/10.2475/ajs.287.5.401, 1987.
Middelburg, J. J., Soetaert, K., and Hagens, M.: Ocean alkalinity, buffering and biogeochemical processes, Rev. Geophys., 58, e2019RG000681, https://doi.org/10.1029/2019RG000681, 2020.
Millero, F. J., Byrne, R. H., Wanninkhof, R., Feely, R., Clayton, T., Murphy, P., and Lamb, M. F.: The internal consistency of CO2 measurements in the equatorial Pacific, Mar. Chem., 44, 269–280, 1993.
Norbisrath, M., Pätsch, J., Dähnke, K., Sanders, T., Schulz, G., van Beusekom, J. E. E., and Thomas, H.: Metabolic alkalinity release from large port facilities (Hamburg, Germany) and impact on coastal carbon storage, Biogeosciences, 19, 5151–5165, https://doi.org/10.5194/bg-19-5151-2022, 2022.
Norbisrath, M., Neumann, A., Dähnke, K., Sanders, T., Schöl, A., van Beusekom, J. E. E., and Thomas, H.: Alkalinity and nitrate dynamics reveal dominance of anammox in a hyper-turbid estuary, Biogeosciences, 20, 4307–4321, https://doi.org/10.5194/bg-20-4307-2023, 2023.
Orr, J. C., Epitalon, J.-M., Dickson, A. G., and Gattuso, J.-P.: Routine uncertainty propagation for the marine carbon dioxide system, Mar. Chem., 207, 84–107, 2018.
Pätsch, J.: Daily Loads of Nutrients, Total Alkalinity, Dissolved Inorganic Carbon and Dissolved Organic Carbon of the European Continental Rivers for the Years 1977–2022, Uni Hamburg [data set], https://wiki.cen.uni-hamburg.de/ifm/ECOHAM/DATA_RIVER (last access: 19 October 2024), 2024.
Petersen, W., Schroeder, F., and Bockelmann, F.-D.: FerryBox-Application of continuous water quality observations along transects in the North Sea, Ocean Dynam., 61, 1541–1554, https://doi.org/10.1007/s10236-011-0445-0, 2011.
Postma, H.: Hydrography of the Dutch Wadden sea, Arch. Neerl. Zool., 10, 405–511, 1954.
R Core Team: R: A language and environment for statistical computing, R version 3.6.1 (2019-07-05), RStudio Version 1.3.1073, R Foundation for Statistical Computing, Vienna, Austria, https://www.R-project.org/ (last access: 18 October 2024), 2019.
Renforth, P. and Henderson, G.: Assessing ocean alkalinity for carbon sequestration, Rev. Geophys., 55, 636–674, https://doi.org/10.1002/2016RG000533, 2017.
Ridderinkhof, H., Zimmerman, J., and Philippart, M.: Tidal exchange between the North Sea and Dutch Wadden Sea and mixing time scales of the tidal basins, Neth. J. Sea Res., 25, 331–350, https://doi.org/10.1016/0077-7579(90)90042-F, 1990.
Røy, H., Lee, J. S., Jansen, S., and de Beer, D.: Tide-driven deep pore-water flow in intertidal sand flats, Limnol. Oceanogr., 53, 1521–1530, https://doi.org/10.4319/lo.2008.53.4.1521, 2008.
Rutgers van der Loeff, M.: Transport van reactief silikaat uit Waddenzee sediment naar het bovenstaande water, NIOZ-rapport, NIOZ Open Repository 304860, http://imis.nioz.nl/imis.php?module=ref&refid=13141&basketaction=add (last access: 21 October 2024), 1974.
Sabine, C. L., Feely, R. A., Gruber, N., Key, R. M., Lee, K., Bullister, J. L., Wanninkhof, R., Wong, C., Wallace, D. W., and Tilbrook, B.: The oceanic sink for anthropogenic CO2, Science, 305, 367–371, https://doi.org/10.1126/science.1097403, 2004.
Santos, I. R., Chen, X., Lecher, A. L., Sawyer, A. H., Moosdorf, N., Rodellas, V., Tamborski, J., Cho, H.-M., Dimova, N., and Sugimoto, R.: Submarine groundwater discharge impacts on coastal nutrient biogeochemistry, Nature Reviews Earth & Environment, 2, 307–323, https://doi.org/10.1038/s43017-021-00152-0, 2021.
Schwichtenberg, F., Callies, U., and van Beusekom, J. E.: Residence times in shallow waters help explain regional differences in Wadden Sea eutrophication, Geo-Mar. Lett., 37, 171–177, https://doi.org/10.1007/s00367-016-0482-2, 2017.
Schwichtenberg, F., Pätsch, J., Böttcher, M. E., Thomas, H., Winde, V., and Emeis, K.-C.: The impact of intertidal areas on the carbonate system of the southern North Sea, Biogeosciences, 17, 4223–4245, https://doi.org/10.5194/bg-17-4223-2020, 2020.
Shadwick, E., Thomas, H., Gratton, Y., Leong, D., Moore, S., Papakyriakou, T., and Prowe, A.: Export of Pacific carbon through the Arctic Archipelago to the North Atlantic, Cont. Shelf Res., 31, 806–816, https://doi.org/10.1016/j.csr.2011.01.014, 2011.
Suchet, P. A. and Probst, J.-L.: Modelling of atmospheric CO2 consumption by chemical weathering of rocks: application to the Garonne, Congo and Amazon basins, Chem. Geol., 107, 205–210, https://doi.org/10.1016/0009-2541(93)90174-H, 1993.
Thomas, H., Bozec, Y., Elkalay, K., and De Baar, H. J.: Enhanced open ocean storage of CO2 from shelf sea pumping, Science, 304, 1005–1008, https://doi.org/10.1126/science.1095491, 2004.
Thomas, H., Schiettecatte, L.-S., Suykens, K., Koné, Y. J. M., Shadwick, E. H., Prowe, A. E. F., Bozec, Y., de Baar, H. J. W., and Borges, A. V.: Enhanced ocean carbon storage from anaerobic alkalinity generation in coastal sediments, Biogeosciences, 6, 267–274, https://doi.org/10.5194/bg-6-267-2009, 2009.
van Bennekom, A., Krijgsman-van Hartingsveld, E., van der Veer, G., and van Voorst, H.: The seasonal cycles of reactive silicate and suspended diatoms in the Dutch Wadden Sea, Neth. J. Sea Res., 8, 174–207, https://doi.org/10.1016/0077-7579(74)90016-7, 1974.
van Beusekom, J. and de Jonge, V.: Long-term changes in Wadden Sea nutrient cycles: importance of organic matter import from the North Sea, Hydrobiologia, 475, 185–194, https://doi.org/10.1023/A:1020361124656, 2002.
van Beusekom, J., Brockmann, U., Hesse, K.-J., Hickel, W., Poremba, K., and Tillmann, U.: The importance of sediments in the transformation and turnover of nutrients and organic matter in the Wadden Sea and German Bight, Deutsche Hydrografische Zeitschrift, 51, 245–266, https://doi.org/10.1007/BF02764176, 1999.
van Beusekom, J. E., Buschbaum, C., and Reise, K.: Wadden Sea tidal basins and the mediating role of the North Sea in ecological processes: scaling up of management?, Ocean Coast. Manage., 68, 69–78, https://doi.org/10.1016/j.ocecoaman.2012.05.002, 2012.
van Beusekom, J. E., Carstensen, J., Dolch, T., Grage, A., Hofmeister, R., Lenhart, H., Kerimoglu, O., Kolbe, K., Pätsch, J., and Rick, J.: Wadden Sea Eutrophication: long-term trends and regional differences, Frontiers in Marine Science, 6, 370, https://doi.org/10.3389/fmars.2019.00370, 2019.
van der Zee, C. and Chou, L.: Seasonal cycling of phosphorus in the Southern Bight of the North Sea, Biogeosciences, 2, 27–42, https://doi.org/10.5194/bg-2-27-2005, 2005.
van Raaphorst, W. and van der Veer, H. W.: The phosphorus budget of the Marsdiep tidal basin (Dutch Wadden Sea) in the period 1950–1985: importance of the exchange with the North Sea, Hydrobiologia, 195, 21–38, https://doi.org/10.1007/BF00026811, 1990.
Voynova, Y. G., Petersen, W., Gehrung, M., Aßmann, S., and King, A. L.: Intertidal regions changing coastal alkalinity: The Wadden Sea-North Sea tidally coupled bioreactor, Limnol. Oceanogr., 64, 1135–1149, 2019.
Wang, Z. A., Kroeger, K. D., Ganju, N. K., Gonneea, M. E., and Chu, S. N.: Intertidal salt marshes as an important source of inorganic carbon to the coastal ocean, Limnol. Oceanogr., 61, 1916–1931, 2016.
Waska, H. and Kim, G.: Submarine groundwater discharge (SGD) as a main nutrient source for benthic and water-column primary production in a large intertidal environment of the Yellow Sea, J. Sea Res., 65, 103–113, https://doi.org/10.1016/j.seares.2010.08.001, 2011.
Wickham, H.: ggplot2: Elegant Graphics for Data Analysis, Springer-Verlag, New York, 2016.
Wolf-Gladrow, D. A., Zeebe, R. E., Klaas, C., Körtzinger, A., and Dickson, A. G.: Total alkalinity: The explicit conservative expression and its application to biogeochemical processes, Mar. Chem., 106, 287–300, https://doi.org/10.1016/j.marchem.2007.01.006, 2007.
Wu, Z., Zhou, H., Zhang, S., and Liu, Y.: Using 222Rn to estimate submarine groundwater discharge (SGD) and the associated nutrient fluxes into Xiangshan Bay, East China Sea, Mar. Pollut. Bull., 73, 183–191, https://doi.org/10.1016/j.marpolbul.2013.05.024, 2013.
Zalasiewicz, J., Williams, M., Steffen, W., and Crutzen, P.: The new world of the Anthropocene, Environ. Sci. Technol., 44, 2228–2231, https://doi.org/10.1021/es903118j, 2010.
Zhang, C., Shi, T., Liu, J., He, Z., Thomas, H., Dong, H., Rinkevich, B., Wang, Y., Hyun, J.-H., and Weinbauer, M.: Eco-engineering approaches for ocean negative carbon emission, Sci. Bull., 67, 2564–2573, https://doi.org/10.1016/j.scib.2022.11.016, 2022.
Short summary
We present an observational study investigating total alkalinity (TA) in the Dutch Wadden Sea. Discrete water samples were used to identify the TA spatial distribution patterns and locate and shed light on TA sources. By observing a tidal cycle, the sediments and pore water exchange were identified as local TA sources. We assumed metabolically driven CaCO3 dissolution as the TA source in the upper, oxic sediments and anaerobic metabolic processes as TA sources in the deeper, anoxic ones.
We present an observational study investigating total alkalinity (TA) in the Dutch Wadden Sea....
