Articles | Volume 10, issue 7
https://doi.org/10.5194/bg-10-5079-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-10-5079-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
26 Jul 2013
Research article |
| 26 Jul 2013
Diapycnal oxygen supply to the tropical North Atlantic oxygen minimum zone
T. Fischer
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
D. Banyte
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
P. Brandt
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
M. Dengler
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
G. Krahmann
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
T. Tanhua
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
M. Visbeck
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
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The Global Carbon Budget 2020 describes the data sets and methodology used to quantify the emissions of carbon dioxide and their partitioning among the atmosphere, land, and ocean. These living data are updated every year to provide the highest transparency and traceability in the reporting of CO2, the key driver of climate change.
Dagmar Hainbucher, Marta Álvarez, Blanca Astray Uceda, Giancarlo Bachi, Vanessa Cardin, Paolo Celentano, Spyros Chaikalis, Maria del Mar Chaves Montero, Giuseppe Civitarese, Noelia M. Fajar, Francois Fripiat, Lennart Gerke, Alexandra Gogou, Elisa F. Guallart, Birte Gülk, Abed El Rahman Hassoun, Nico Lange, Andrea Rochner, Chiara Santinelli, Tobias Steinhoff, Toste Tanhua, Lidia Urbini, Dimitrios Velaoras, Fabian Wolf, and Andreas Welsch
Earth Syst. Sci. Data, 12, 2747–2763, https://doi.org/10.5194/essd-12-2747-2020, https://doi.org/10.5194/essd-12-2747-2020, 2020
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We report on data from an oceanographic cruise in the Mediterranean Sea (MSM72, March 2018). The main objective of the cruise was to contribute to the understanding of long-term changes and trends in physical and biogeochemical parameters, such as the anthropogenic carbon uptake, and further assess the hydrographical situation after the Eastern and Western Mediterranean Transients. Multidisciplinary measurements were conducted on a predominantly
zonal section throughout the Mediterranean Sea.
Jan Lüdke, Marcus Dengler, Stefan Sommer, David Clemens, Sören Thomsen, Gerd Krahmann, Andrew W. Dale, Eric P. Achterberg, and Martin Visbeck
Ocean Sci., 16, 1347–1366, https://doi.org/10.5194/os-16-1347-2020, https://doi.org/10.5194/os-16-1347-2020, 2020
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We analyse the intraseasonal variability of the alongshore circulation off Peru in early 2017, this circulation is very important for the supply of nutrients to the upwelling regime. The causes of this variability and its impact on the biogeochemistry are investigated. The poleward flow is strengthened during the observed time period, likely by a downwelling coastal trapped wave. The stronger current causes an increase in nitrate and reduces the deficit of fixed nitrogen relative to phosphorus.
Ruifang C. Xie, Frédéric A. C. Le Moigne, Insa Rapp, Jan Lüdke, Beat Gasser, Marcus Dengler, Volker Liebetrau, and Eric P. Achterberg
Biogeosciences, 17, 4919–4936, https://doi.org/10.5194/bg-17-4919-2020, https://doi.org/10.5194/bg-17-4919-2020, 2020
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Thorium-234 (234Th) is widely used to study carbon fluxes from the surface ocean to depth. But few studies stress the relevance of oceanic advection and diffusion on the downward 234Th fluxes in nearshore environments. Our study in offshore Peru showed strong temporal variations in both the importance of physical processes on 234Th flux estimates and the oceanic residence time of 234Th, whereas salinity-derived seawater 238U activities accounted for up to 40 % errors in 234Th flux estimates.
Daniel Broullón, Fiz F. Pérez, Antón Velo, Mario Hoppema, Are Olsen, Taro Takahashi, Robert M. Key, Toste Tanhua, J. Magdalena Santana-Casiano, and Alex Kozyr
Earth Syst. Sci. Data, 12, 1725–1743, https://doi.org/10.5194/essd-12-1725-2020, https://doi.org/10.5194/essd-12-1725-2020, 2020
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This work offers a vision of the global ocean regarding the carbon cycle and the implications of ocean acidification through a climatology of a changing variable in the context of climate change: total dissolved inorganic carbon. The climatology was designed through artificial intelligence techniques to represent the mean state of the present ocean. It is very useful to introduce in models to evaluate the state of the ocean from different perspectives.
Insa Rapp, Christian Schlosser, Jan-Lukas Menzel Barraqueta, Bernhard Wenzel, Jan Lüdke, Jan Scholten, Beat Gasser, Patrick Reichert, Martha Gledhill, Marcus Dengler, and Eric P. Achterberg
Biogeosciences, 16, 4157–4182, https://doi.org/10.5194/bg-16-4157-2019, https://doi.org/10.5194/bg-16-4157-2019, 2019
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The availability of iron (Fe) affects phytoplankton growth in large parts of the ocean. Shelf sediments, particularly in oxygen minimum zones, are a major source of Fe and other essential micronutrients, such as cobalt (Co) and manganese (Mn). We observed enhanced concentrations of Fe, Co, and Mn corresponding with low oxygen concentrations along the Mauritanian shelf, indicating that the projected future decrease in oxygen concentrations may result in increases in Fe, Mn, and Co concentrations.
Are Olsen, Nico Lange, Robert M. Key, Toste Tanhua, Marta Álvarez, Susan Becker, Henry C. Bittig, Brendan R. Carter, Leticia Cotrim da Cunha, Richard A. Feely, Steven van Heuven, Mario Hoppema, Masao Ishii, Emil Jeansson, Steve D. Jones, Sara Jutterström, Maren K. Karlsen, Alex Kozyr, Siv K. Lauvset, Claire Lo Monaco, Akihiko Murata, Fiz F. Pérez, Benjamin Pfeil, Carsten Schirnick, Reiner Steinfeldt, Toru Suzuki, Maciej Telszewski, Bronte Tilbrook, Anton Velo, and Rik Wanninkhof
Earth Syst. Sci. Data, 11, 1437–1461, https://doi.org/10.5194/essd-11-1437-2019, https://doi.org/10.5194/essd-11-1437-2019, 2019
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GLODAP is a data product for ocean inorganic carbon and related biogeochemical variables measured by chemical analysis of water bottle samples at scientific cruises. GLODAPv2.2019 is the first update of GLODAPv2 from 2016. The data that are included have been subjected to extensive quality control, including systematic evaluation of measurement biases. This version contains data from 840 hydrographic cruises covering the world's oceans from 1972 to 2017.
Sinikka T. Lennartz, Marc von Hobe, Dennis Booge, Henry C. Bittig, Tim Fischer, Rafael Gonçalves-Araujo, Kerstin B. Ksionzek, Boris P. Koch, Astrid Bracher, Rüdiger Röttgers, Birgit Quack, and Christa A. Marandino
Ocean Sci., 15, 1071–1090, https://doi.org/10.5194/os-15-1071-2019, https://doi.org/10.5194/os-15-1071-2019, 2019
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The ocean emits the gases carbonyl sulfide (OCS) and carbon disulfide (CS2), which affect our climate. The goal of this study was to quantify the rates at which both gases are produced in the eastern tropical South Pacific (ETSP), one of the most productive oceanic regions worldwide. Both gases are produced by reactions triggered by sunlight, but we found that the amount produced depends on different factors. Our results improve numerical models to predict oceanic concentrations of both gases.
Daniel Broullón, Fiz F. Pérez, Antón Velo, Mario Hoppema, Are Olsen, Taro Takahashi, Robert M. Key, Toste Tanhua, Melchor González-Dávila, Emil Jeansson, Alex Kozyr, and Steven M. A. C. van Heuven
Earth Syst. Sci. Data, 11, 1109–1127, https://doi.org/10.5194/essd-11-1109-2019, https://doi.org/10.5194/essd-11-1109-2019, 2019
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In this work, we are contributing to the knowledge of the consequences of climate change in the ocean. We have focused on a variable related to this process: total alkalinity. We have designed a monthly climatology of total alkalinity using artificial intelligence techniques, that is, a representation of the average capacity of the ocean in the last decades to decelerate the consequences of climate change. The climatology is especially useful to infer the evolution of the ocean through models.
Tim Fischer, Annette Kock, Damian L. Arévalo-Martínez, Marcus Dengler, Peter Brandt, and Hermann W. Bange
Biogeosciences, 16, 2307–2328, https://doi.org/10.5194/bg-16-2307-2019, https://doi.org/10.5194/bg-16-2307-2019, 2019
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We investigated air–sea gas exchange in oceanic upwelling regions for the case of nitrous oxide off Peru. In this region, routine concentration measurements from ships at 5 m or 10 m depth prove to overestimate surface (bulk) concentration. Thus, standard estimates of gas exchange will show systematic error. This is due to very shallow stratified layers that inhibit exchange between surface water and waters below and can exist for several days. Maximum bias occurs in moderate wind conditions.
Alexandra N. Loginova, Sören Thomsen, Marcus Dengler, Jan Lüdke, and Anja Engel
Biogeosciences, 16, 2033–2047, https://doi.org/10.5194/bg-16-2033-2019, https://doi.org/10.5194/bg-16-2033-2019, 2019
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High primary production in the Peruvian upwelling system is followed by rapid heterotrophic utilization of organic matter and supports the formation of one of the most intense oxygen minimum zones (OMZs) in the world. Here, we estimated vertical fluxes of oxygen and dissolved organic matter (DOM) from the surface to the OMZ. Our results suggest that DOM remineralization substantially reduces oxygen concentration in the upper water column and controls the shape of the upper oxycline.
Soeren Thomsen, Johannes Karstensen, Rainer Kiko, Gerd Krahmann, Marcus Dengler, and Anja Engel
Biogeosciences, 16, 979–998, https://doi.org/10.5194/bg-16-979-2019, https://doi.org/10.5194/bg-16-979-2019, 2019
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Physical and biogeochemical observations from an autonomous underwater vehicle in combination with ship-based measurements are used to investigate remote and local drivers of the oxygen and nutrient variability off Mauritania. Beside the transport of oxygen and nutrients characteristics from remote areas towards Mauritania also local remineralization of organic material close to the seabed seems to be important for the distribution of oxygen and nutrients.
Mian Liu and Toste Tanhua
Ocean Sci. Discuss., https://doi.org/10.5194/os-2018-140, https://doi.org/10.5194/os-2018-140, 2019
Publication in OS not foreseen
Pingyang Li, Jens Mühle, Stephen A. Montzka, David E. Oram, Benjamin R. Miller, Ray F. Weiss, Paul J. Fraser, and Toste Tanhua
Ocean Sci., 15, 33–60, https://doi.org/10.5194/os-15-33-2019, https://doi.org/10.5194/os-15-33-2019, 2019
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Use of CFCs as oceanic transient tracers is difficult for recently ventilated water masses as their atmospheric mole fractions have been decreasing. To explore novel tracers, we synthesized consistent annual mean atmospheric histories of HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 (CF4) and PFC-116 in both hemispheres and reconstructed their solubility functions in water and seawater. This work is also potentially useful for tracer studies in a range of natural waters.
Yao Fu, Johannes Karstensen, and Peter Brandt
Ocean Sci., 14, 589–616, https://doi.org/10.5194/os-14-589-2018, https://doi.org/10.5194/os-14-589-2018, 2018
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Hydrographic analysis in the Atlantic along 14.5° N and 24.5° N shows that between the periods of 1989/92 and 2013/15, the Antarctic Intermediate Water became warmer and saltier at 14.5° N, and that the Antarctic Bottom Water became lighter at both latitudes. By applying a box inverse model, the Atlantic Meridional Overturning Circulation (AMOC) was determined. Comparison among the inverse solution, GECCO2, RAPID, and MOVE shows that the AMOC has not significantly changed in the past 20 years.
Fabrice Ardhuin, Yevgueny Aksenov, Alvise Benetazzo, Laurent Bertino, Peter Brandt, Eric Caubet, Bertrand Chapron, Fabrice Collard, Sophie Cravatte, Jean-Marc Delouis, Frederic Dias, Gérald Dibarboure, Lucile Gaultier, Johnny Johannessen, Anton Korosov, Georgy Manucharyan, Dimitris Menemenlis, Melisa Menendez, Goulven Monnier, Alexis Mouche, Frédéric Nouguier, George Nurser, Pierre Rampal, Ad Reniers, Ernesto Rodriguez, Justin Stopa, Céline Tison, Clément Ubelmann, Erik van Sebille, and Jiping Xie
Ocean Sci., 14, 337–354, https://doi.org/10.5194/os-14-337-2018, https://doi.org/10.5194/os-14-337-2018, 2018
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The Sea surface KInematics Multiscale (SKIM) monitoring mission is a proposal for a future satellite that is designed to measure ocean currents and waves. Using a Doppler radar, the accurate measurement of currents requires the removal of the mean velocity due to ocean wave motions. This paper describes the main processing steps needed to produce currents and wave data from the radar measurements. With this technique, SKIM can provide unprecedented coverage and resolution, over the global ocean.
Yao Fu, Johannes Karstensen, and Peter Brandt
Ocean Sci., 13, 531–549, https://doi.org/10.5194/os-13-531-2017, https://doi.org/10.5194/os-13-531-2017, 2017
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Meridional Ekman transport in the tropical Atlantic was estimated directly by using observed ageostrophic velocity, and indirectly by using wind stress data. The direct and indirect methods agree well with each other. The top of the pycnocline represents the Ekman depth better than the mixed layer depth and a constant depth. The Ekman heat and salt fluxes calculated from sea surface temperature and salinity or from high-resolution temperature and salinity profile data differ only marginally.
Johannes Hahn, Peter Brandt, Sunke Schmidtko, and Gerd Krahmann
Ocean Sci., 13, 551–576, https://doi.org/10.5194/os-13-551-2017, https://doi.org/10.5194/os-13-551-2017, 2017
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Recent studies have shown that the eastern tropical North Atlantic is subject to a strong decrease of the oceanic oxygen concentration in the upper 1000 m from the 1960s to today. By analyzing a broad observational data set, this study found an even stronger oxygen decrease in the upper 400 m throughout the past decade, whereas oxygen increase was found below (400–1000 m). Changes in the strength of the zonal currents are the most likely reason for the observed decadal oxygen changes.
James C. Orr, Raymond G. Najjar, Olivier Aumont, Laurent Bopp, John L. Bullister, Gokhan Danabasoglu, Scott C. Doney, John P. Dunne, Jean-Claude Dutay, Heather Graven, Stephen M. Griffies, Jasmin G. John, Fortunat Joos, Ingeborg Levin, Keith Lindsay, Richard J. Matear, Galen A. McKinley, Anne Mouchet, Andreas Oschlies, Anastasia Romanou, Reiner Schlitzer, Alessandro Tagliabue, Toste Tanhua, and Andrew Yool
Geosci. Model Dev., 10, 2169–2199, https://doi.org/10.5194/gmd-10-2169-2017, https://doi.org/10.5194/gmd-10-2169-2017, 2017
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The Ocean Model Intercomparison Project (OMIP) is a model comparison effort under Phase 6 of the Coupled Model Intercomparison Project (CMIP6). Its physical component is described elsewhere in this special issue. Here we describe its ocean biogeochemical component (OMIP-BGC), detailing simulation protocols and analysis diagnostics. Simulations focus on ocean carbon, other biogeochemical tracers, air-sea exchange of CO2 and related gases, and chemical tracers used to evaluate modeled circulation.
Johannes Karstensen, Florian Schütte, Alice Pietri, Gerd Krahmann, Björn Fiedler, Damian Grundle, Helena Hauss, Arne Körtzinger, Carolin R. Löscher, Pierre Testor, Nuno Vieira, and Martin Visbeck
Biogeosciences, 14, 2167–2181, https://doi.org/10.5194/bg-14-2167-2017, https://doi.org/10.5194/bg-14-2167-2017, 2017
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High-resolution observational data from underwater gliders and ships are used to investigate drivers and pathways of nutrient upwelling in high-productive whirling ecosystems (eddies). The data suggest that the upwelling is created by the interaction of wind-induced internal waves with the local rotation of the eddy. Because of differences in nutrient and oxygen pathways, a low-oxygen core is established at shallow depth in the high-productive eddies.
Leif G. Anderson, Göran Björk, Ola Holby, Sara Jutterström, Carl Magnus Mörth, Matt O'Regan, Christof Pearce, Igor Semiletov, Christian Stranne, Tim Stöven, Toste Tanhua, Adam Ulfsbo, and Martin Jakobsson
Ocean Sci., 13, 349–363, https://doi.org/10.5194/os-13-349-2017, https://doi.org/10.5194/os-13-349-2017, 2017
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We use data collected in 2014 to show that the outflow of nutrient-rich water occurs much further to the west than has been reported in the past. We suggest that this is due to much less summer sea-ice coverage in the northwestern East Siberian Sea than in the past decades. Further, our data support a more complicated flow pattern in the region where the Mendeleev Ridge reaches the shelf compared to the general cyclonic circulation within the individual basins as suggested historically.
Mohamed Ayache, Jean-Claude Dutay, Anne Mouchet, Nadine Tisnérat-Laborde, Paolo Montagna, Toste Tanhua, Giuseppe Siani, and Philippe Jean-Baptiste
Biogeosciences, 14, 1197–1213, https://doi.org/10.5194/bg-14-1197-2017, https://doi.org/10.5194/bg-14-1197-2017, 2017
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A high-resolution dynamical model was used to give the first simulation of the distribution of natural and anthropogenic radiocarbon (14C) across the whole Mediterranean Sea. The model correctly simulates the main features of 14C distribution during and after the bomb perturbation. The results demonstrate the major influence of the flux of Atlantic water through the Strait of Gibraltar, and a significant increase in 14C in the Aegean deep water during the Eastern Mediterranean Transient event.
Florian Schütte, Johannes Karstensen, Gerd Krahmann, Helena Hauss, Björn Fiedler, Peter Brandt, Martin Visbeck, and Arne Körtzinger
Biogeosciences, 13, 5865–5881, https://doi.org/10.5194/bg-13-5865-2016, https://doi.org/10.5194/bg-13-5865-2016, 2016
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Mesoscale eddies with very low–oxygen concentrations at shallow depth have been recently discovered in the eastern tropical North Atlantic. Our analysis shows that low oxygen eddies occur more frequent than expected and are found even close to the equator (8° N). From budget calculations we show that an oxygen reduction of 7 µmol/kg in the depth range of 50–150 m in the eastern tropical North Atlantic (peak reduction is 16 µmol/kg at 100 m depth) can be associated with the dispersion of these eddies.
Meike Becker, Nils Andersen, Helmut Erlenkeuser, Matthew P. Humphreys, Toste Tanhua, and Arne Körtzinger
Earth Syst. Sci. Data, 8, 559–570, https://doi.org/10.5194/essd-8-559-2016, https://doi.org/10.5194/essd-8-559-2016, 2016
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The stable carbon isotope composition of dissolved inorganic carbon (δ13C-DIC) can be used to quantify fluxes within the marine carbon system such as the exchange between ocean and atmosphere or the amount of anthropogenic carbon in the water column. In this study, an internally consistent δ13C-DIC dataset for the North Atlantic is presented. The data have undergone a secondary quality control during which systematic biases between the respective cruises have been quantified and adjusted.
Björn Fiedler, Damian S. Grundle, Florian Schütte, Johannes Karstensen, Carolin R. Löscher, Helena Hauss, Hannes Wagner, Alexandra Loginova, Rainer Kiko, Péricles Silva, Toste Tanhua, and Arne Körtzinger
Biogeosciences, 13, 5633–5647, https://doi.org/10.5194/bg-13-5633-2016, https://doi.org/10.5194/bg-13-5633-2016, 2016
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Oxygen-depleted mesoscale features in the open eastern tropical North Atlantic, which are formed in the Mauritanian upwelling region, were discovered recently. This study examines biogeochemical structure and magnitudes of related processes within these isolated water masses. We found very low oxygen concentrations and strongly enhanced acidity at near-surface depth. Oxygen utilization and downward carbon export were found to exceed known values for this ocean region.
Are Olsen, Robert M. Key, Steven van Heuven, Siv K. Lauvset, Anton Velo, Xiaohua Lin, Carsten Schirnick, Alex Kozyr, Toste Tanhua, Mario Hoppema, Sara Jutterström, Reiner Steinfeldt, Emil Jeansson, Masao Ishii, Fiz F. Pérez, and Toru Suzuki
Earth Syst. Sci. Data, 8, 297–323, https://doi.org/10.5194/essd-8-297-2016, https://doi.org/10.5194/essd-8-297-2016, 2016
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The GLODAPv2 data product collects data from more than 700 hydrographic cruises into a global and internally calibrated product. It provides access to the data from almost all ocean carbon cruises carried out since the 1970s and is a unique resource for marine science, in particular regarding the ocean carbon cycle. GLODAPv2 will form the foundation for future routine synthesis of hydrographic data of the same sort.
Siv K. Lauvset, Robert M. Key, Are Olsen, Steven van Heuven, Anton Velo, Xiaohua Lin, Carsten Schirnick, Alex Kozyr, Toste Tanhua, Mario Hoppema, Sara Jutterström, Reiner Steinfeldt, Emil Jeansson, Masao Ishii, Fiz F. Perez, Toru Suzuki, and Sylvain Watelet
Earth Syst. Sci. Data, 8, 325–340, https://doi.org/10.5194/essd-8-325-2016, https://doi.org/10.5194/essd-8-325-2016, 2016
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This paper describes the mapped climatologies that are part of the Global Ocean Data Analysis Project Version 2 (GLODAPv2). GLODAPv2 is a uniformly calibrated open ocean data product on inorganic carbon and carbon-relevant variables. Global mapped climatologies of the total dissolved inorganic carbon, total alkalinity, pH, saturation state of calcite and aragonite, anthropogenic carbon, preindustrial carbon content, inorganic macronutrients, oxygen, salinity, and temperature have been created.
Lothar Stramma, Tim Fischer, Damian S. Grundle, Gerd Krahmann, Hermann W. Bange, and Christa A. Marandino
Ocean Sci., 12, 861–873, https://doi.org/10.5194/os-12-861-2016, https://doi.org/10.5194/os-12-861-2016, 2016
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Results from a research cruise on R/V Sonne to the eastern tropical Pacific in October 2015 during the 2015–2016 El Niño show the transition of current, hydrographic, and nutrient conditions to El Niño conditions in the eastern tropical Pacific in October 2015. Although in early 2015 the El Niño was strong and in October 2015 showed a clear El Niño influence on the EUC, in the eastern tropical Pacific the measurements only showed developing El Niño water mass distributions.
Florian Schütte, Peter Brandt, and Johannes Karstensen
Ocean Sci., 12, 663–685, https://doi.org/10.5194/os-12-663-2016, https://doi.org/10.5194/os-12-663-2016, 2016
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We want to examine the characteristics of mesoscale eddies in the tropical northeastern Atlantic. They serve as transport agents, exporting water from the coast into the open ocean. Traditionally eddies are categorized with respect to their rotation: cyclonic and anticyclonic. But we could identify, with a combination of different satellite products, a third type called "anticyclonic mode-water eddy" transporting much larger anomalies. We propose a distinction into three classes for further studies.
Lorenzo Rovelli, Marcus Dengler, Mark Schmidt, Stefan Sommer, Peter Linke, and Daniel F. McGinnis
Biogeosciences, 13, 1609–1620, https://doi.org/10.5194/bg-13-1609-2016, https://doi.org/10.5194/bg-13-1609-2016, 2016
Tim Stöven, Toste Tanhua, Mario Hoppema, and Wilken-Jon von Appen
Ocean Sci., 12, 319–333, https://doi.org/10.5194/os-12-319-2016, https://doi.org/10.5194/os-12-319-2016, 2016
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The article describes transient tracer distributions of CFC-12 and SF6 in the Fram Strait in 2012. The SF6 excess and the anthropogenic carbon content in this area was estimated assuming a standard parameterization of the inverse-Gaussian–transit-time distribution. Hydrographic data were obtained along a mooring array at 78°50’N and a mean velocity field was used for flux estimates.
L. Stramma, R. Czeschel, T. Tanhua, P. Brandt, M. Visbeck, and B. S. Giese
Ocean Sci., 12, 153–167, https://doi.org/10.5194/os-12-153-2016, https://doi.org/10.5194/os-12-153-2016, 2016
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The subsurface circulation in the eastern tropical North Atlantic OMZ is derived from velocity, float and tracer data and data assimilation results, and shows a cyclonic flow around the Guinea Dome reaching into the oxygen minimum zone. The stronger cyclonic flow around the Guinea Dome in 2009 seem to be connected to a strong Atlantic Meridional Mode (AMM) event.
A continuous deoxygenation trend of the low oxygen layer was confirmed.
Eddy influence is weak south of the Cape Verde Islands.
S. Walter, A. Kock, T. Steinhoff, B. Fiedler, P. Fietzek, J. Kaiser, M. Krol, M. E. Popa, Q. Chen, T. Tanhua, and T. Röckmann
Biogeosciences, 13, 323–340, https://doi.org/10.5194/bg-13-323-2016, https://doi.org/10.5194/bg-13-323-2016, 2016
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Oceans are a source of H2, an indirect greenhouse gas. Measurements constraining the temporal and spatial patterns of oceanic H2 emissions are sparse and although H2 is assumed to be produced mainly biologically, direct evidence for biogenic marine production was lacking. By analyzing the H2 isotopic composition (δD) we were able to constrain the global H2 budget in more detail, verify biogenic production and point to additional sources. We also showed that current models are reasonably working.
R. Steinfeldt, J. Sültenfuß, M. Dengler, T. Fischer, and M. Rhein
Biogeosciences, 12, 7519–7533, https://doi.org/10.5194/bg-12-7519-2015, https://doi.org/10.5194/bg-12-7519-2015, 2015
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The coastal upwelling systems, e.g. off Peru and Mauritania,
are key regions for the emissions of climate relevant trace gases
from the ocean into the atmosphere. Here, gases and nutrients are
transported into the ocean mixed layer from below. The upwelling velocities,
however, are too small to be measured directly.
We use the enhancement of helium-3 in upwelled
waters to quantify the vertical velocity,
which varies between 1.0 and 2.5 metres per day in the coastal regions.
H. Hepach, B. Quack, S. Raimund, T. Fischer, E. L. Atlas, and A. Bracher
Biogeosciences, 12, 6369–6387, https://doi.org/10.5194/bg-12-6369-2015, https://doi.org/10.5194/bg-12-6369-2015, 2015
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This manuscript covers the first measurements of CHBr3, CH2Br2 and CH3I from the equatorial Atlantic during the Cold Tongue season, identifying this region and season as a source for these compounds. For the first time, we calculated diapycnal fluxes, and showed that the fluxes from below the mixed layer to the surface are not sufficient to balance the mixed layer budget. Hence, we conclude that mixed layer production has to take place despite a pronounced sub-mixed-layer-maximum.
T. Stöven, T. Tanhua, M. Hoppema, and J. L. Bullister
Ocean Sci., 11, 699–718, https://doi.org/10.5194/os-11-699-2015, https://doi.org/10.5194/os-11-699-2015, 2015
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We use a suite of transient tracer measurements from a Southern Ocean sector southeast of Africa collected from 1998 and 2012 to quantify ventilation and change in ventilation. We found that the ventilation can be constrained by an inverse Gaussian transit time distribution north of the Subantarctic Front. We do not find any significant changes in upper ocean ventilation during this time period.
R. Czeschel, L. Stramma, R. A. Weller, and T. Fischer
Ocean Sci., 11, 455–470, https://doi.org/10.5194/os-11-455-2015, https://doi.org/10.5194/os-11-455-2015, 2015
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Mean circulation in the eastern tropical South Pacific in 50-600m depth is modified by seasonal variability and eddies on the poleward side of the oxygen minimum zone(OMZ). Floats with parking depth at 400m show westward flow in the equatorial channel, sluggish flow in the northern part of the OMZ, and passage of eddies with oxygen anomalies. Net community production rates were estimated from a float. Oxygen decrease in 50-300m depth since 1976 is related to an increase in nitrate and phosphate.
J. Karstensen, B. Fiedler, F. Schütte, P. Brandt, A. Körtzinger, G. Fischer, R. Zantopp, J. Hahn, M. Visbeck, and D. Wallace
Biogeosciences, 12, 2597–2605, https://doi.org/10.5194/bg-12-2597-2015, https://doi.org/10.5194/bg-12-2597-2015, 2015
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This study is the first report of the formation of dead zones in the open ocean. A combination of multiple ocean observing system elements (mooring, floats, satellites, ships) allowed us to reconstruct the generation of the dead zones and to connect the formation to enhanced respiration within mesoscale ocean eddies. The dead zones present specific threats to the ecosystem, such as the interruption of the diurnal migration of zooplankters.
A. W. Dale, S. Sommer, U. Lomnitz, I. Montes, T. Treude, V. Liebetrau, J. Gier, C. Hensen, M. Dengler, K. Stolpovsky, L. D. Bryant, and K. Wallmann
Biogeosciences, 12, 1537–1559, https://doi.org/10.5194/bg-12-1537-2015, https://doi.org/10.5194/bg-12-1537-2015, 2015
P. Brandt, H. W. Bange, D. Banyte, M. Dengler, S.-H. Didwischus, T. Fischer, R. J. Greatbatch, J. Hahn, T. Kanzow, J. Karstensen, A. Körtzinger, G. Krahmann, S. Schmidtko, L. Stramma, T. Tanhua, and M. Visbeck
Biogeosciences, 12, 489–512, https://doi.org/10.5194/bg-12-489-2015, https://doi.org/10.5194/bg-12-489-2015, 2015
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Our observational study looks at the structure of the eastern tropical North Atlantic (ETNA) oxygen minimum zone (OMZ) in comparison with the less-ventilated, eastern tropical South Pacific OMZ. We quantify the OMZ’s oxygen budget composed of consumption, advection, lateral and vertical mixing. Substantial oxygen variability is observed on interannual to multidecadal timescales. The deoxygenation of the ETNA OMZ during the last decades represents a substantial imbalance of the oxygen budget.
A. Oviedo, P. Ziveri, M. Álvarez, and T. Tanhua
Ocean Sci., 11, 13–32, https://doi.org/10.5194/os-11-13-2015, https://doi.org/10.5194/os-11-13-2015, 2015
D. Hainbucher, A. Rubino, V. Cardin, T. Tanhua, K. Schroeder, and M. Bensi
Ocean Sci., 10, 669–682, https://doi.org/10.5194/os-10-669-2014, https://doi.org/10.5194/os-10-669-2014, 2014
J. Karstensen, T. Liblik, J. Fischer, K. Bumke, and G. Krahmann
Biogeosciences, 11, 3603–3617, https://doi.org/10.5194/bg-11-3603-2014, https://doi.org/10.5194/bg-11-3603-2014, 2014
T. Stöven and T. Tanhua
Ocean Sci., 10, 439–457, https://doi.org/10.5194/os-10-439-2014, https://doi.org/10.5194/os-10-439-2014, 2014
P. Malanotte-Rizzoli, V. Artale, G. L. Borzelli-Eusebi, S. Brenner, A. Crise, M. Gacic, N. Kress, S. Marullo, M. Ribera d'Alcalà, S. Sofianos, T. Tanhua, A. Theocharis, M. Alvarez, Y. Ashkenazy, A. Bergamasco, V. Cardin, S. Carniel, G. Civitarese, F. D'Ortenzio, J. Font, E. Garcia-Ladona, J. M. Garcia-Lafuente, A. Gogou, M. Gregoire, D. Hainbucher, H. Kontoyannis, V. Kovacevic, E. Kraskapoulou, G. Kroskos, A. Incarbona, M. G. Mazzocchi, M. Orlic, E. Ozsoy, A. Pascual, P.-M. Poulain, W. Roether, A. Rubino, K. Schroeder, J. Siokou-Frangou, E. Souvermezoglou, M. Sprovieri, J. Tintoré, and G. Triantafyllou
Ocean Sci., 10, 281–322, https://doi.org/10.5194/os-10-281-2014, https://doi.org/10.5194/os-10-281-2014, 2014
M. Álvarez, H. Sanleón-Bartolomé, T. Tanhua, L. Mintrop, A. Luchetta, C. Cantoni, K. Schroeder, and G. Civitarese
Ocean Sci., 10, 69–92, https://doi.org/10.5194/os-10-69-2014, https://doi.org/10.5194/os-10-69-2014, 2014
A. Schneider, T. Tanhua, W. Roether, and R. Steinfeldt
Ocean Sci., 10, 1–16, https://doi.org/10.5194/os-10-1-2014, https://doi.org/10.5194/os-10-1-2014, 2014
F. Ziska, B. Quack, K. Abrahamsson, S. D. Archer, E. Atlas, T. Bell, J. H. Butler, L. J. Carpenter, C. E. Jones, N. R. P. Harris, H. Hepach, K. G. Heumann, C. Hughes, J. Kuss, K. Krüger, P. Liss, R. M. Moore, A. Orlikowska, S. Raimund, C. E. Reeves, W. Reifenhäuser, A. D. Robinson, C. Schall, T. Tanhua, S. Tegtmeier, S. Turner, L. Wang, D. Wallace, J. Williams, H. Yamamoto, S. Yvon-Lewis, and Y. Yokouchi
Atmos. Chem. Phys., 13, 8915–8934, https://doi.org/10.5194/acp-13-8915-2013, https://doi.org/10.5194/acp-13-8915-2013, 2013
T. Tanhua, D. Hainbucher, K. Schroeder, V. Cardin, M. Álvarez, and G. Civitarese
Ocean Sci., 9, 789–803, https://doi.org/10.5194/os-9-789-2013, https://doi.org/10.5194/os-9-789-2013, 2013
T. Tanhua, D. Hainbucher, V. Cardin, M. Álvarez, G. Civitarese, A. P. McNichol, and R. M. Key
Earth Syst. Sci. Data, 5, 289–294, https://doi.org/10.5194/essd-5-289-2013, https://doi.org/10.5194/essd-5-289-2013, 2013
W. Cheah, B. B. Taylor, S. Wiegmann, S. Raimund, G. Krahmann, B. Quack, and A. Bracher
Biogeosciences Discuss., https://doi.org/10.5194/bgd-10-12115-2013, https://doi.org/10.5194/bgd-10-12115-2013, 2013
Revised manuscript not accepted
S. Khatiwala, T. Tanhua, S. Mikaloff Fletcher, M. Gerber, S. C. Doney, H. D. Graven, N. Gruber, G. A. McKinley, A. Murata, A. F. Ríos, and C. L. Sabine
Biogeosciences, 10, 2169–2191, https://doi.org/10.5194/bg-10-2169-2013, https://doi.org/10.5194/bg-10-2169-2013, 2013
Related subject area
Biogeochemistry: Open Ocean
Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: a stable isotope approach
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone
Optimal parameters for the ocean's nutrient, carbon, and oxygen cycles compensate for circulation biases but replumb the biological pump
Importance of multiple sources of iron for the upper-ocean biogeochemistry over the northern Indian Ocean
Exploring the role of different data types and timescales in the quality of marine biogeochemical model calibration
All about nitrite: exploring nitrite sources and sinks in the eastern tropical North Pacific oxygen minimum zone
Fossil coccolith morphological attributes as a new proxy for deep ocean carbonate chemistry
Reconstructing ocean carbon storage with CMIP6 Earth system models and synthetic Argo observations
Using machine learning and Biogeochemical-Argo (BGC-Argo) floats to assess biogeochemical models and optimize observing system design
The representation of alkalinity and the carbonate pump from CMIP5 to CMIP6 Earth system models and implications for the carbon cycle
Model estimates of metazoans' contributions to the biological carbon pump
Reconstructing the ocean’s mesopelagic zone carbon budget: sensitivity and estimation of parameters associated with prokaryotic remineralization
Tracing differences in iron supply to the Mid-Atlantic Ridge valley between hydrothermal vent sites: implications for the addition of iron to the deep ocean
Nitrite cycling in the primary nitrite maxima of the eastern tropical North Pacific
The Fingerprint of Climate Variability on the Surface Ocean Cycling of Iron and its Isotopes
Hotspots and drivers of compound marine heatwaves and low net primary production extremes
Ecosystem impacts of marine heat waves in the northeast Pacific
Tracing the role of Arctic shelf processes in Si and N cycling and export through the Fram Strait: insights from combined silicon and nitrate isotopes
Controls on the relative abundances and rates of nitrifying microorganisms in the ocean
The response of diazotrophs to nutrient amendment in the South China Sea and western North Pacific
Seasonal dynamics and annual budget of dissolved inorganic carbon in the northwestern Mediterranean deep convection region
Influence of GEOTRACES data distribution and misfit function choice on objective parameter retrieval in a marine zinc cycle model
Physiological flexibility of phytoplankton impacts modelled chlorophyll and primary production across the North Pacific Ocean
Observation-constrained estimates of the global ocean carbon sink from Earth system models
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise)
Controlling factors on the global distribution of a representative marine non-cyanobacterial diazotroph phylotype (Gamma A)
Summer trends and drivers of sea surface fCO2 and pH changes observed in the southern Indian Ocean over the last two decades (1998–2019)
Global nutrient cycling by commercially targeted marine fish
Major processes of the dissolved cobalt cycle in the North and equatorial Pacific Ocean
The impact of the South-East Madagascar Bloom on the oceanic CO2 sink
Nitrite regeneration in the oligotrophic Atlantic Ocean
Bridging the gaps between particulate backscattering measurements and modeled particulate organic carbon in the ocean
Biological production in two contrasted regions of the Mediterranean Sea during the oligotrophic period: an estimate based on the diel cycle of optical properties measured by BioGeoChemical-Argo profiling floats
Acidification of the Nordic Seas
Reconstruction of global surface ocean pCO2 using region-specific predictors based on a stepwise FFNN regression algorithm
Biogeochemical controls on ammonium accumulation in the surface layer of the Southern Ocean
Oxygen export to the deep ocean following Labrador Sea Water formation
N2 fixation in the Mediterranean Sea related to the composition of the diazotrophic community and impact of dust under present and future environmental conditions
Dissolution of a submarine carbonate platform by a submerged lake of acidic seawater
Seasonal flux patterns and carbon transport from low-oxygen eddies at the Cape Verde Ocean Observatory: lessons learned from a time series sediment trap study (2009–2016)
Subsurface iron accumulation and rapid aluminum removal in the Mediterranean following African dust deposition
Long-distance particle transport to the central Ionian Sea
Deep chlorophyll maximum and nutricline in the Mediterranean Sea: emerging properties from a multi-platform assimilated biogeochemical model experiment
Phosphorus cycling in the upper waters of the Mediterranean Sea (PEACETIME cruise): relative contribution of external and internal sources
Fast local warming is the main driver of recent deoxygenation in the northern Arabian Sea
Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system
Impact of dust addition on the metabolism of Mediterranean plankton communities and carbon export under present and future conditions of pH and temperature
Comparing CLE-AdCSV applications using SA and TAC to determine the Fe-binding characteristics of model ligands in seawater
Impact of dust addition on Mediterranean plankton communities under present and future conditions of pH and temperature: an experimental overview
Reviews and syntheses: Trends in primary production in the Bay of Bengal – is it at a tipping point?
Anna Belcher, Sian F. Henley, Katharine Hendry, Marianne Wootton, Lisa Friberg, Ursula Dallman, Tong Wang, Christopher Coath, and Clara Manno
Biogeosciences, 20, 3573–3591, https://doi.org/10.5194/bg-20-3573-2023, https://doi.org/10.5194/bg-20-3573-2023, 2023
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The oceans play a crucial role in the uptake of atmospheric carbon dioxide, particularly the Southern Ocean. The biological pumping of carbon from the surface to the deep ocean is key to this. Using sediment trap samples from the Scotia Sea, we examine biogeochemical fluxes of carbon, nitrogen, and biogenic silica and their stable isotope compositions. We find phytoplankton community structure and physically mediated processes are important controls on particulate fluxes to the deep ocean.
Asmita Singh, Susanne Fietz, Sandy J. Thomalla, Nicolas Sanchez, Murat V. Ardelan, Sébastien Moreau, Hanna M. Kauko, Agneta Fransson, Melissa Chierici, Saumik Samanta, Thato N. Mtshali, Alakendra N. Roychoudhury, and Thomas J. Ryan-Keogh
Biogeosciences, 20, 3073–3091, https://doi.org/10.5194/bg-20-3073-2023, https://doi.org/10.5194/bg-20-3073-2023, 2023
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Despite the scarcity of iron in the Southern Ocean, seasonal blooms occur due to changes in nutrient and light availability. Surprisingly, during an autumn bloom in the Antarctic sea-ice zone, the results from incubation experiments showed no significant photophysiological response of phytoplankton to iron addition. This suggests that ambient iron concentrations were sufficient, challenging the notion of iron deficiency in the Southern Ocean through extended iron-replete post-bloom conditions.
Benoît Pasquier, Mark Holzer, Matthew A. Chamberlain, Richard J. Matear, Nathaniel L. Bindoff, and François W. Primeau
Biogeosciences, 20, 2985–3009, https://doi.org/10.5194/bg-20-2985-2023, https://doi.org/10.5194/bg-20-2985-2023, 2023
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Modeling the ocean's carbon and oxygen cycles accurately is challenging. Parameter optimization improves the fit to observed tracers but can introduce artifacts in the biological pump. Organic-matter production and subsurface remineralization rates adjust to compensate for circulation biases, changing the pathways and timescales with which nutrients return to the surface. Circulation biases can thus strongly alter the system’s response to ecological change, even when parameters are optimized.
Priyanka Banerjee
Biogeosciences, 20, 2613–2643, https://doi.org/10.5194/bg-20-2613-2023, https://doi.org/10.5194/bg-20-2613-2023, 2023
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This study shows that atmospheric deposition is the most important source of iron to the upper northern Indian Ocean for phytoplankton growth. This is followed by iron from continental-shelf sediment. Phytoplankton increase following iron addition is possible only with high background levels of nitrate. Vertical mixing is the most important physical process supplying iron to the upper ocean in this region throughout the year. The importance of ocean currents in supplying iron varies seasonally.
Iris Kriest, Julia Getzlaff, Angela Landolfi, Volkmar Sauerland, Markus Schartau, and Andreas Oschlies
Biogeosciences, 20, 2645–2669, https://doi.org/10.5194/bg-20-2645-2023, https://doi.org/10.5194/bg-20-2645-2023, 2023
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Global biogeochemical ocean models are often subjectively assessed and tuned against observations. We applied different strategies to calibrate a global model against observations. Although the calibrated models show similar tracer distributions at the surface, they differ in global biogeochemical fluxes, especially in global particle flux. Simulated global volume of oxygen minimum zones varies strongly with calibration strategy and over time, rendering its temporal extrapolation difficult.
John C. Tracey, Andrew R. Babbin, Elizabeth Wallace, Xin Sun, Katherine L. DuRussel, Claudia Frey, Donald E. Martocello III, Tyler Tamasi, Sergey Oleynik, and Bess B. Ward
Biogeosciences, 20, 2499–2523, https://doi.org/10.5194/bg-20-2499-2023, https://doi.org/10.5194/bg-20-2499-2023, 2023
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Nitrogen (N) is essential for life; thus, its availability plays a key role in determining marine productivity. Using incubations of seawater spiked with a rare form of N measurable on a mass spectrometer, we quantified microbial pathways that determine marine N availability. The results show that pathways that recycle N have higher rates than those that result in its loss from biomass and present new evidence for anaerobic nitrite oxidation, a process long thought to be strictly aerobic.
Amanda Gerotto, Hongrui Zhang, Renata Hanae Nagai, Heather M. Stoll, Rubens César Lopes Figueira, Chuanlian Liu, and Iván Hernández-Almeida
Biogeosciences, 20, 1725–1739, https://doi.org/10.5194/bg-20-1725-2023, https://doi.org/10.5194/bg-20-1725-2023, 2023
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Based on the analysis of the response of coccolithophores’ morphological attributes in a laboratory dissolution experiment and surface sediment samples from the South China Sea, we proposed that the thickness shape (ks) factor of fossil coccoliths together with the normalized ks variation, which is the ratio of the standard deviation of ks (σ) over the mean ks (σ/ks), is a robust and novel proxy to reconstruct past changes in deep ocean carbon chemistry.
Katherine E. Turner, Doug M. Smith, Anna Katavouta, and Richard G. Williams
Biogeosciences, 20, 1671–1690, https://doi.org/10.5194/bg-20-1671-2023, https://doi.org/10.5194/bg-20-1671-2023, 2023
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We present a new method for reconstructing ocean carbon using climate models and temperature and salinity observations. To test this method, we reconstruct modelled carbon using synthetic observations consistent with current sampling programmes. Sensitivity tests show skill in reconstructing carbon trends and variability within the upper 2000 m. Our results indicate that this method can be used for a new global estimate for ocean carbon content.
Alexandre Mignot, Hervé Claustre, Gianpiero Cossarini, Fabrizio D'Ortenzio, Elodie Gutknecht, Julien Lamouroux, Paolo Lazzari, Coralie Perruche, Stefano Salon, Raphaëlle Sauzède, Vincent Taillandier, and Anna Teruzzi
Biogeosciences, 20, 1405–1422, https://doi.org/10.5194/bg-20-1405-2023, https://doi.org/10.5194/bg-20-1405-2023, 2023
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Numerical models of ocean biogeochemistry are becoming a major tool to detect and predict the impact of climate change on marine resources and monitor ocean health. Here, we demonstrate the use of the global array of BGC-Argo floats for the assessment of biogeochemical models. We first detail the handling of the BGC-Argo data set for model assessment purposes. We then present 23 assessment metrics to quantify the consistency of BGC model simulations with respect to BGC-Argo data.
Alban Planchat, Lester Kwiatkowski, Laurent Bopp, Olivier Torres, James R. Christian, Momme Butenschön, Tomas Lovato, Roland Séférian, Matthew A. Chamberlain, Olivier Aumont, Michio Watanabe, Akitomo Yamamoto, Andrew Yool, Tatiana Ilyina, Hiroyuki Tsujino, Kristen M. Krumhardt, Jörg Schwinger, Jerry Tjiputra, John P. Dunne, and Charles Stock
Biogeosciences, 20, 1195–1257, https://doi.org/10.5194/bg-20-1195-2023, https://doi.org/10.5194/bg-20-1195-2023, 2023
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Ocean alkalinity is critical to the uptake of atmospheric carbon and acidification in surface waters. We review the representation of alkalinity and the associated calcium carbonate cycle in Earth system models. While many parameterizations remain present in the latest generation of models, there is a general improvement in the simulated alkalinity distribution. This improvement is related to an increase in the export of biotic calcium carbonate, which closer resembles observations.
Jérôme Pinti, Tim DeVries, Tommy Norin, Camila Serra-Pompei, Roland Proud, David A. Siegel, Thomas Kiørboe, Colleen M. Petrik, Ken H. Andersen, Andrew S. Brierley, and André W. Visser
Biogeosciences, 20, 997–1009, https://doi.org/10.5194/bg-20-997-2023, https://doi.org/10.5194/bg-20-997-2023, 2023
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Large numbers of marine organisms such as zooplankton and fish perform daily vertical migration between the surface (at night) and the depths (in the daytime). This fascinating migration is important for the carbon cycle, as these organisms actively bring carbon to depths where it is stored away from the atmosphere for a long time. Here, we quantify the contributions of different animals to this carbon drawdown and storage and show that fish are important to the biological carbon pump.
Chloé Baumas, Robin Fuchs, Marc Garel, Jean-Christophe Poggiale, Laurent Memery, Frédéric A. C. Le Moigne, and Christian Tamburini
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-34, https://doi.org/10.5194/bg-2023-34, 2023
Revised manuscript accepted for BG
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Through the sink of particles in the ocean, carbon (C) is exported and sequestered when reaching 1000 m. Attempts to quantify the C exported versus consumed by heterotrophs have increased. Yet, most of the conducted estimations have led to C demands several times higher than C export. The choice of parameters greatly impact the results. As theses parameters are overlooked, non-accurate values are often used. In this study we show that C budgets can be well balanced when using appropriate values.
Alastair J. M. Lough, Alessandro Tagliabue, Clément Demasy, Joseph A. Resing, Travis Mellett, Neil J. Wyatt, and Maeve C. Lohan
Biogeosciences, 20, 405–420, https://doi.org/10.5194/bg-20-405-2023, https://doi.org/10.5194/bg-20-405-2023, 2023
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Iron is a key nutrient for ocean primary productivity. Hydrothermal vents are a source of iron to the oceans, but the size of this source is poorly understood. This study examines the variability in iron inputs between hydrothermal vents in different geological settings. The vents studied release different amounts of Fe, resulting in plumes with similar dissolved iron concentrations but different particulate concentrations. This will help to refine modelling of iron-limited ocean productivity.
Nicole M. Travis, Colette L. Kelly, Margaret R. Mulholland, and Karen L. Casciotti
Biogeosciences, 20, 325–347, https://doi.org/10.5194/bg-20-325-2023, https://doi.org/10.5194/bg-20-325-2023, 2023
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The primary nitrite maximum is a ubiquitous upper ocean feature where nitrite accumulates, but we still do not understand its formation and the co-occurring microbial processes involved. Using correlative methods and rates measurements, we found strong spatial patterns between environmental conditions and depths of the nitrite maxima, but not the maximum concentrations. Nitrification was the dominant source of nitrite, with occasional high nitrite production from phytoplankton near the coast.
Daniela König and Alessandro Tagliabue
Biogeosciences Discuss., https://doi.org/10.5194/bg-2022-241, https://doi.org/10.5194/bg-2022-241, 2023
Revised manuscript accepted for BG
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Using model simulations, we show that natural and anthropogenic changes in the global climate leave a distinct fingerprint in the isotopic signatures of iron in the surface ocean. We find that these climate effects on iron isotopes are often caused by the redistribution of iron from different external sources to the ocean, due to changes in ocean currents, and by changes in algal growth, which take up iron. Thus, isotopes may help detect climate-induced changes in iron supply and algal uptake.
Natacha Le Grix, Jakob Zscheischler, Keith B. Rodgers, Ryohei Yamaguchi, and Thomas L. Frölicher
Biogeosciences, 19, 5807–5835, https://doi.org/10.5194/bg-19-5807-2022, https://doi.org/10.5194/bg-19-5807-2022, 2022
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Compound events threaten marine ecosystems. Here, we investigate the potentially harmful combination of marine heatwaves with low phytoplankton productivity. Using satellite-based observations, we show that these compound events are frequent in the low latitudes. We then investigate the drivers of these compound events using Earth system models. The models share similar drivers in the low latitudes but disagree in the high latitudes due to divergent factors limiting phytoplankton production.
Abigale M. Wyatt, Laure Resplandy, and Adrian Marchetti
Biogeosciences, 19, 5689–5705, https://doi.org/10.5194/bg-19-5689-2022, https://doi.org/10.5194/bg-19-5689-2022, 2022
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Marine heat waves (MHWs) are a frequent event in the northeast Pacific, with a large impact on the region's ecosystems. Large phytoplankton in the North Pacific Transition Zone are greatly affected by decreased nutrients, with less of an impact in the Alaskan Gyre. For small phytoplankton, MHWs increase the spring small phytoplankton population in both regions thanks to reduced light limitation. In both zones, this results in a significant decrease in the ratio of large to small phytoplankton.
Margot C. F. Debyser, Laetitia Pichevin, Robyn E. Tuerena, Paul A. Dodd, Antonia Doncila, and Raja S. Ganeshram
Biogeosciences, 19, 5499–5520, https://doi.org/10.5194/bg-19-5499-2022, https://doi.org/10.5194/bg-19-5499-2022, 2022
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We focus on the exchange of key nutrients for algae production between the Arctic and Atlantic oceans through the Fram Strait. We show that the export of dissolved silicon here is controlled by the availability of nitrate which is influenced by denitrification on Arctic shelves. We suggest that any future changes in the river inputs of silica and changes in denitrification due to climate change will impact the amount of silicon exported, with impacts on Atlantic algal productivity and ecology.
Emily J. Zakem, Barbara Bayer, Wei Qin, Alyson E. Santoro, Yao Zhang, and Naomi M. Levine
Biogeosciences, 19, 5401–5418, https://doi.org/10.5194/bg-19-5401-2022, https://doi.org/10.5194/bg-19-5401-2022, 2022
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We use a microbial ecosystem model to quantitatively explain the mechanisms controlling observed relative abundances and nitrification rates of ammonia- and nitrite-oxidizing microorganisms in the ocean. We also estimate how much global carbon fixation can be associated with chemoautotrophic nitrification. Our results improve our understanding of the controls on nitrification, laying the groundwork for more accurate predictions in global climate models.
Zuozhu Wen, Thomas J. Browning, Rongbo Dai, Wenwei Wu, Weiying Li, Xiaohua Hu, Wenfang Lin, Lifang Wang, Xin Liu, Zhimian Cao, Haizheng Hong, and Dalin Shi
Biogeosciences, 19, 5237–5250, https://doi.org/10.5194/bg-19-5237-2022, https://doi.org/10.5194/bg-19-5237-2022, 2022
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Fe and P are key factors controlling the biogeography and activity of marine N2-fixing microorganisms. We found lower abundance and activity of N2 fixers in the northern South China Sea than around the western boundary of the North Pacific, and N2 fixation rates switched from Fe–P co-limitation to P limitation. We hypothesize the Fe supply rates and Fe utilization strategies of each N2 fixer are important in regulating spatial variability in community structure across the study area.
Caroline Ulses, Claude Estournel, Patrick Marsaleix, Karline Soetaert, Marine Fourrier, Laurent Coppola, Dominique Lefèvre, Franck Touratier, Catherine Goyet, Véronique Guglielmi, Fayçal Kessouri, Pierre Testor, and Xavier Durrieu de Madron
Biogeosciences Discuss., https://doi.org/10.5194/bg-2022-219, https://doi.org/10.5194/bg-2022-219, 2022
Revised manuscript accepted for BG
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Deep convection plays a key role in the circulation, thermodynamics and biogeochemical cycles in the Mediterranean Sea, considered as a hotspot of biodiversity and climate change. In this study, we investigate the seasonal cycle and annual budget of dissolved inorganic carbon in the deep convection area of the northwestern Mediterranean Sea.
Claudia Eisenring, Sophy E. Oliver, Samar Khatiwala, and Gregory F. de Souza
Biogeosciences, 19, 5079–5106, https://doi.org/10.5194/bg-19-5079-2022, https://doi.org/10.5194/bg-19-5079-2022, 2022
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Given the sparsity of observational constraints on micronutrients such as zinc (Zn), we assess the sensitivities of a framework for objective parameter optimisation in an oceanic Zn cycling model. Our ensemble of optimisations towards synthetic data with varying kinds of uncertainty shows that deficiencies related to model complexity and the choice of the misfit function generally have a greater impact on the retrieval of model Zn uptake behaviour than does the limitation of data coverage.
Yoshikazu Sasai, Sherwood Lan Smith, Eko Siswanto, Hideharu Sasaki, and Masami Nonaka
Biogeosciences, 19, 4865–4882, https://doi.org/10.5194/bg-19-4865-2022, https://doi.org/10.5194/bg-19-4865-2022, 2022
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We have investigated the adaptive response of phytoplankton growth to changing light, nutrients, and temperature over the North Pacific using two physical-biological models. We compare modeled chlorophyll and primary production from an inflexible control model (InFlexPFT), which assumes fixed carbon (C):nitrogen (N):chlorophyll (Chl) ratios, to a recently developed flexible phytoplankton functional type model (FlexPFT), which incorporates photoacclimation and variable C:N:Chl ratios.
Jens Terhaar, Thomas L. Frölicher, and Fortunat Joos
Biogeosciences, 19, 4431–4457, https://doi.org/10.5194/bg-19-4431-2022, https://doi.org/10.5194/bg-19-4431-2022, 2022
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Estimates of the ocean sink of anthropogenic carbon vary across various approaches. We show that the global ocean carbon sink can be estimated by three parameters, two of which approximate the ocean ventilation in the Southern Ocean and the North Atlantic, and one of which approximates the chemical capacity of the ocean to take up carbon. With observations of these parameters, we estimate that the global ocean carbon sink is 10 % larger than previously assumed, and we cut uncertainties in half.
Natasha René van Horsten, Hélène Planquette, Géraldine Sarthou, Thomas James Ryan-Keogh, Nolwenn Lemaitre, Thato Nicholas Mtshali, Alakendra Roychoudhury, and Eva Bucciarelli
Biogeosciences, 19, 3209–3224, https://doi.org/10.5194/bg-19-3209-2022, https://doi.org/10.5194/bg-19-3209-2022, 2022
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The remineralisation proxy, barite, was measured along 30°E in the southern Indian Ocean during early austral winter. To our knowledge this is the first reported Southern Ocean winter study. Concentrations throughout the water column were comparable to observations during spring to autumn. By linking satellite primary production to this proxy a possible annual timescale is proposed. These findings also suggest possible carbon remineralisation from satellite data on a basin scale.
Zhibo Shao and Ya-Wei Luo
Biogeosciences, 19, 2939–2952, https://doi.org/10.5194/bg-19-2939-2022, https://doi.org/10.5194/bg-19-2939-2022, 2022
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Non-cyanobacterial diazotrophs (NCDs) may be an important player in fixing N2 in the ocean. By conducting meta-analyses, we found that a representative marine NCD phylotype, Gamma A, tends to inhabit ocean environments with high productivity, low iron concentration and high light intensity. It also appears to be more abundant inside cyclonic eddies. Our study suggests a niche differentiation of NCDs from cyanobacterial diazotrophs as the latter prefers low-productivity and high-iron oceans.
Coraline Leseurre, Claire Lo Monaco, Gilles Reverdin, Nicolas Metzl, Jonathan Fin, Claude Mignon, and Léa Benito
Biogeosciences, 19, 2599–2625, https://doi.org/10.5194/bg-19-2599-2022, https://doi.org/10.5194/bg-19-2599-2022, 2022
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Decadal trends of fugacity of CO2 (fCO2), total alkalinity (AT), total carbon (CT) and pH in surface waters are investigated in different domains of the southern Indian Ocean (45°S–57°S) from ongoing and station observations regularly conducted in summer over the period 1998–2019. The fCO2 increase and pH decrease are mainly driven by anthropogenic CO2 estimated just below the summer mixed layer, as well as by a warming south of the polar front or in the fertilized waters near Kerguelen Island.
Priscilla Le Mézo, Jérôme Guiet, Kim Scherrer, Daniele Bianchi, and Eric Galbraith
Biogeosciences, 19, 2537–2555, https://doi.org/10.5194/bg-19-2537-2022, https://doi.org/10.5194/bg-19-2537-2022, 2022
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This study quantifies the role of commercially targeted fish biomass in the cycling of three important nutrients (N, P, and Fe), relative to nutrients otherwise available in water and to nutrients required by primary producers, and the impact of fishing. We use a model of commercially targeted fish biomass constrained by fish catch and stock assessment data to assess the contributions of fish at the global scale, at the time of the global peak catch and prior to industrial fishing.
Rebecca Chmiel, Nathan Lanning, Allison Laubach, Jong-Mi Lee, Jessica Fitzsimmons, Mariko Hatta, William Jenkins, Phoebe Lam, Matthew McIlvin, Alessandro Tagliabue, and Mak Saito
Biogeosciences, 19, 2365–2395, https://doi.org/10.5194/bg-19-2365-2022, https://doi.org/10.5194/bg-19-2365-2022, 2022
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Dissolved cobalt is present in trace amounts in seawater and is a necessary nutrient for marine microbes. On a transect from the Alaskan coast to Tahiti, we measured seawater concentrations of dissolved cobalt. Here, we describe several interesting features of the Pacific cobalt cycle including cobalt sources along the Alaskan coast and Hawaiian vents, deep-ocean particle formation, cobalt activity in low-oxygen regions, and how our samples compare to a global biogeochemical model’s predictions.
Nicolas Metzl, Claire Lo Monaco, Coraline Leseurre, Céline Ridame, Jonathan Fin, Claude Mignon, Marion Gehlen, and Thi Tuyet Trang Chau
Biogeosciences, 19, 1451–1468, https://doi.org/10.5194/bg-19-1451-2022, https://doi.org/10.5194/bg-19-1451-2022, 2022
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During an oceanographic cruise conducted in January 2020 in the south-western Indian Ocean, we observed very low CO2 concentrations associated with a strong phytoplankton bloom that occurred south-east of Madagascar. This biological event led to a strong regional CO2 ocean sink not previously observed.
Darren R. Clark, Andrew P. Rees, Charissa M. Ferrera, Lisa Al-Moosawi, Paul J. Somerfield, Carolyn Harris, Graham D. Quartly, Stephen Goult, Glen Tarran, and Gennadi Lessin
Biogeosciences, 19, 1355–1376, https://doi.org/10.5194/bg-19-1355-2022, https://doi.org/10.5194/bg-19-1355-2022, 2022
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Measurements of microbial processes were made in the sunlit open ocean during a research cruise (AMT19) between the UK and Chile. These help us to understand how microbial communities maintain the function of remote ecosystems. We find that the nitrogen cycling microbes which produce nitrite respond to changes in the environment. Our insights will aid the development of models that aim to replicate and ultimately project how marine environments may respond to ongoing climate change.
Martí Galí, Marcus Falls, Hervé Claustre, Olivier Aumont, and Raffaele Bernardello
Biogeosciences, 19, 1245–1275, https://doi.org/10.5194/bg-19-1245-2022, https://doi.org/10.5194/bg-19-1245-2022, 2022
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Part of the organic matter produced by plankton in the upper ocean is exported to the deep ocean. This process, known as the biological carbon pump, is key for the regulation of atmospheric carbon dioxide and global climate. However, the dynamics of organic particles below the upper ocean layer are not well understood. Here we compared the measurements acquired by autonomous robots in the top 1000 m of the ocean to a numerical model, which can help improve future climate projections.
Marie Barbieux, Julia Uitz, Alexandre Mignot, Collin Roesler, Hervé Claustre, Bernard Gentili, Vincent Taillandier, Fabrizio D'Ortenzio, Hubert Loisel, Antoine Poteau, Edouard Leymarie, Christophe Penkerc'h, Catherine Schmechtig, and Annick Bricaud
Biogeosciences, 19, 1165–1194, https://doi.org/10.5194/bg-19-1165-2022, https://doi.org/10.5194/bg-19-1165-2022, 2022
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This study assesses marine biological production in two Mediterranean systems representative of vast desert-like (oligotrophic) areas encountered in the global ocean. We use a novel approach based on non-intrusive high-frequency in situ measurements by two profiling robots, the BioGeoChemical-Argo (BGC-Argo) floats. Our results indicate substantial yet variable production rates and contribution to the whole water column of the subsurface layer, typically considered steady and non-productive.
Filippa Fransner, Friederike Fröb, Jerry Tjiputra, Nadine Goris, Siv K. Lauvset, Ingunn Skjelvan, Emil Jeansson, Abdirahman Omar, Melissa Chierici, Elizabeth Jones, Agneta Fransson, Sólveig R. Ólafsdóttir, Truls Johannessen, and Are Olsen
Biogeosciences, 19, 979–1012, https://doi.org/10.5194/bg-19-979-2022, https://doi.org/10.5194/bg-19-979-2022, 2022
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Ocean acidification, a direct consequence of the CO2 release by human activities, is a serious threat to marine ecosystems. In this study, we conduct a detailed investigation of the acidification of the Nordic Seas, from 1850 to 2100, by using a large set of samples taken during research cruises together with numerical model simulations. We estimate the effects of changes in different environmental factors on the rate of acidification and its potential effects on cold-water corals.
Guorong Zhong, Xuegang Li, Jinming Song, Baoxiao Qu, Fan Wang, Yanjun Wang, Bin Zhang, Xiaoxia Sun, Wuchang Zhang, Zhenyan Wang, Jun Ma, Huamao Yuan, and Liqin Duan
Biogeosciences, 19, 845–859, https://doi.org/10.5194/bg-19-845-2022, https://doi.org/10.5194/bg-19-845-2022, 2022
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A predictor selection algorithm was constructed to decrease the predicting error in the surface ocean partial pressure of CO2 (pCO2) mapping by finding better combinations of pCO2 predictors in different regions. Compared with previous research using the same combination of predictors in all regions, using different predictors selected by the algorithm in different regions can effectively decrease pCO2 predicting errors.
Shantelle Smith, Katye E. Altieri, Mhlangabezi Mdutyana, David R. Walker, Ruan G. Parrott, Sedick Gallie, Kurt A. M. Spence, Jessica M. Burger, and Sarah E. Fawcett
Biogeosciences, 19, 715–741, https://doi.org/10.5194/bg-19-715-2022, https://doi.org/10.5194/bg-19-715-2022, 2022
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Ammonium is a crucial yet poorly understood component of the Southern Ocean nitrogen cycle. We attribute our finding of consistently high ammonium concentrations in the winter mixed layer to limited ammonium consumption and sustained ammonium production, conditions under which the Southern Ocean becomes a source of carbon dioxide to the atmosphere. From similar data collected over an annual cycle, we propose a seasonal cycle for ammonium in shallow polar waters – a first for the Southern Ocean.
Jannes Koelling, Dariia Atamanchuk, Johannes Karstensen, Patricia Handmann, and Douglas W. R. Wallace
Biogeosciences, 19, 437–454, https://doi.org/10.5194/bg-19-437-2022, https://doi.org/10.5194/bg-19-437-2022, 2022
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In this study, we investigate oxygen variability in the deep western boundary current in the Labrador Sea from multiyear moored records. We estimate that about half of the oxygen taken up in the interior Labrador Sea by air–sea gas exchange during deep water formation is exported southward the same year. Our results underline the complexity of the oxygen uptake and export in the Labrador Sea and highlight the important role this region plays in supplying oxygen to the deep ocean.
Céline Ridame, Julie Dinasquet, Søren Hallstrøm, Estelle Bigeard, Lasse Riemann, France Van Wambeke, Matthieu Bressac, Elvira Pulido-Villena, Vincent Taillandier, Fréderic Gazeau, Antonio Tovar-Sanchez, Anne-Claire Baudoux, and Cécile Guieu
Biogeosciences, 19, 415–435, https://doi.org/10.5194/bg-19-415-2022, https://doi.org/10.5194/bg-19-415-2022, 2022
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We show that in the Mediterranean Sea spatial variability in N2 fixation is related to the diazotrophic community composition reflecting different nutrient requirements among species. Nutrient supply by Saharan dust is of great importance to diazotrophs, as shown by the strong stimulation of N2 fixation after a simulated dust event under present and future climate conditions; the magnitude of stimulation depends on the degree of limitation related to the diazotrophic community composition.
Matthew P. Humphreys, Erik H. Meesters, Henk de Haas, Szabina Karancz, Louise Delaigue, Karel Bakker, Gerard Duineveld, Siham de Goeyse, Andreas F. Haas, Furu Mienis, Sharyn Ossebaar, and Fleur C. van Duyl
Biogeosciences, 19, 347–358, https://doi.org/10.5194/bg-19-347-2022, https://doi.org/10.5194/bg-19-347-2022, 2022
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A series of submarine sinkholes were recently discovered on Luymes Bank, part of Saba Bank, a carbonate platform in the Caribbean Netherlands. Here, we investigate the waters inside these sinkholes for the first time. One of the sinkholes contained a body of dense, low-oxygen and low-pH water, which we call the
acid lake. We use measurements of seawater chemistry to work out what processes were responsible for forming the acid lake and discuss the consequences for the carbonate platform.
Gerhard Fischer, Oscar E. Romero, Johannes Karstensen, Karl-Heinz Baumann, Nasrollah Moradi, Morten Iversen, Götz Ruhland, Marco Klann, and Arne Körtzinger
Biogeosciences, 18, 6479–6500, https://doi.org/10.5194/bg-18-6479-2021, https://doi.org/10.5194/bg-18-6479-2021, 2021
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Low-oxygen eddies in the eastern subtropical North Atlantic can form an oasis for phytoplankton growth. Here we report on particle flux dynamics at the oligotrophic Cape Verde Ocean Observatory. We observed consistent flux patterns during the passages of low-oxygen eddies. We found distinct flux peaks in late winter, clearly exceeding background fluxes. Our findings suggest that the low-oxygen eddies sequester higher organic carbon than expected for oligotrophic settings.
Matthieu Bressac, Thibaut Wagener, Nathalie Leblond, Antonio Tovar-Sánchez, Céline Ridame, Vincent Taillandier, Samuel Albani, Sophie Guasco, Aurélie Dufour, Stéphanie H. M. Jacquet, François Dulac, Karine Desboeufs, and Cécile Guieu
Biogeosciences, 18, 6435–6453, https://doi.org/10.5194/bg-18-6435-2021, https://doi.org/10.5194/bg-18-6435-2021, 2021
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Phytoplankton growth is limited by the availability of iron in about 50 % of the ocean. Atmospheric deposition of desert dust represents a key source of iron. Here, we present direct observations of dust deposition in the Mediterranean Sea. A key finding is that the input of iron from dust primarily occurred in the deep ocean, while previous studies mainly focused on the ocean surface. This new insight will enable us to better represent controls on global marine productivity in models.
Léo Berline, Andrea Michelangelo Doglioli, Anne Petrenko, Stéphanie Barrillon, Boris Espinasse, Frederic A. C. Le Moigne, François Simon-Bot, Melilotus Thyssen, and François Carlotti
Biogeosciences, 18, 6377–6392, https://doi.org/10.5194/bg-18-6377-2021, https://doi.org/10.5194/bg-18-6377-2021, 2021
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While the Ionian Sea is considered a nutrient-depleted and low-phytoplankton biomass area, it is a crossroad for water mass circulation. In the central Ionian Sea, we observed a strong contrast in particle distribution across a ~100 km long transect. Using remote sensing and Lagrangian simulations, we suggest that this contrast finds its origin in the long-distance transport of particles from the north, west and east of the Ionian Sea, where phytoplankton production was more intense.
Anna Teruzzi, Giorgio Bolzon, Laura Feudale, and Gianpiero Cossarini
Biogeosciences, 18, 6147–6166, https://doi.org/10.5194/bg-18-6147-2021, https://doi.org/10.5194/bg-18-6147-2021, 2021
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During summer, maxima of phytoplankton chlorophyll concentration (DCM) occur in the subsurface of the Mediterranean Sea and can play a relevant role in carbon sequestration into the ocean interior. A numerical model based on in situ and satellite observations provides insights into the range of DCM conditions across the relatively small Mediterranean Sea and shows a western DCM that is 25 % shallower and with a higher phytoplankton chlorophyll concentration than in the eastern Mediterranean.
Elvira Pulido-Villena, Karine Desboeufs, Kahina Djaoudi, France Van Wambeke, Stéphanie Barrillon, Andrea Doglioli, Anne Petrenko, Vincent Taillandier, Franck Fu, Tiphanie Gaillard, Sophie Guasco, Sandra Nunige, Sylvain Triquet, and Cécile Guieu
Biogeosciences, 18, 5871–5889, https://doi.org/10.5194/bg-18-5871-2021, https://doi.org/10.5194/bg-18-5871-2021, 2021
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We report on phosphorus dynamics in the surface layer of the Mediterranean Sea. Highly sensitive phosphate measurements revealed vertical gradients above the phosphacline. The relative contribution of diapycnal fluxes to total external supply of phosphate to the mixed layer decreased towards the east, where atmospheric deposition dominated. Taken together, external sources of phosphate contributed little to total supply, which was mainly sustained by enzymatic hydrolysis of organic phosphorus.
Zouhair Lachkar, Michael Mehari, Muchamad Al Azhar, Marina Lévy, and Shafer Smith
Biogeosciences, 18, 5831–5849, https://doi.org/10.5194/bg-18-5831-2021, https://doi.org/10.5194/bg-18-5831-2021, 2021
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This study documents and quantifies a significant recent oxygen decline in the upper layers of the Arabian Sea and explores its drivers. Using a modeling approach we show that the fast local warming of sea surface is the main factor causing this oxygen drop. Concomitant summer monsoon intensification contributes to this trend, although to a lesser extent. These changes exacerbate oxygen depletion in the subsurface, threatening marine habitats and altering the local biogeochemistry.
France Van Wambeke, Vincent Taillandier, Karine Desboeufs, Elvira Pulido-Villena, Julie Dinasquet, Anja Engel, Emilio Marañón, Céline Ridame, and Cécile Guieu
Biogeosciences, 18, 5699–5717, https://doi.org/10.5194/bg-18-5699-2021, https://doi.org/10.5194/bg-18-5699-2021, 2021
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Simultaneous in situ measurements of (dry and wet) atmospheric deposition and biogeochemical stocks and fluxes in the sunlit waters of the open Mediterranean Sea revealed complex physical and biological processes occurring within the mixed layer. Nitrogen (N) budgets were computed to compare the sources and sinks of N in the mixed layer. The transitory effect observed after a wet dust deposition impacted the microbial food web down to the deep chlorophyll maximum.
Frédéric Gazeau, France Van Wambeke, Emilio Marañón, Maria Pérez-Lorenzo, Samir Alliouane, Christian Stolpe, Thierry Blasco, Nathalie Leblond, Birthe Zäncker, Anja Engel, Barbara Marie, Julie Dinasquet, and Cécile Guieu
Biogeosciences, 18, 5423–5446, https://doi.org/10.5194/bg-18-5423-2021, https://doi.org/10.5194/bg-18-5423-2021, 2021
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Our study shows that the impact of dust deposition on primary production depends on the initial composition and metabolic state of the tested community and is constrained by the amount of nutrients added, to sustain both the fast response of heterotrophic prokaryotes and the delayed one of phytoplankton. Under future environmental conditions, heterotrophic metabolism will be more impacted than primary production, therefore reducing the capacity of surface waters to sequester anthropogenic CO2.
Loes J. A. Gerringa, Martha Gledhill, Indah Ardiningsih, Niels Muntjewerf, and Luis M. Laglera
Biogeosciences, 18, 5265–5289, https://doi.org/10.5194/bg-18-5265-2021, https://doi.org/10.5194/bg-18-5265-2021, 2021
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For 3 decades, competitive ligand exchange–adsorptive cathodic stripping voltammetry was used to estimate the Fe-binding capacity of organic matter in seawater. In this paper the performance of the competing ligands is compared through the analysis of a series of model ligands.
The main finding of this paper is that the determined speciation parameters are not independent of the application, making interpretation of Fe speciation data more complex than it was thought before.
Frédéric Gazeau, Céline Ridame, France Van Wambeke, Samir Alliouane, Christian Stolpe, Jean-Olivier Irisson, Sophie Marro, Jean-Michel Grisoni, Guillaume De Liège, Sandra Nunige, Kahina Djaoudi, Elvira Pulido-Villena, Julie Dinasquet, Ingrid Obernosterer, Philippe Catala, and Cécile Guieu
Biogeosciences, 18, 5011–5034, https://doi.org/10.5194/bg-18-5011-2021, https://doi.org/10.5194/bg-18-5011-2021, 2021
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This paper shows that the impacts of Saharan dust deposition in different Mediterranean basins are as strong as those observed in coastal waters but differed substantially between the three tested stations, differences attributed to variable initial metabolic states. A stronger impact of warming and acidification on mineralization suggests a decreased capacity of Mediterranean surface communities to sequester CO2 following the deposition of atmospheric particles in the coming decades.
Carolin R. Löscher
Biogeosciences, 18, 4953–4963, https://doi.org/10.5194/bg-18-4953-2021, https://doi.org/10.5194/bg-18-4953-2021, 2021
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The Bay of Bengal (BoB) is classically seen as an ocean region with low primary production, which has been predicted to decrease even further. Here, the importance of such a trend is used to explore what could happen to the BoB's low-oxygen core waters if primary production decreases. Lower biological production leads to less oxygen loss in deeper waters by respiration; thus it could be that oxygen will not further decrease and the BoB will not become anoxic, different to other low-oxygen areas.
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