Articles | Volume 16, issue 9
https://doi.org/10.5194/bg-16-2079-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-16-2079-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
17 May 2019
Research article |
| 17 May 2019
| 17 May 2019
Investigating the effect of El Niño on nitrous oxide distribution in the eastern tropical South Pacific
GEOMAR Helmholtz Centre of Ocean Research Kiel, Kiel, 24105, Germany
Mark A. Altabet
School for Marine Science & Technology, University of Massachusetts
Dartmouth, New Bedford, Massachusetts, USA
Hermann W. Bange
GEOMAR Helmholtz Centre of Ocean Research Kiel, Kiel, 24105, Germany
Michelle I. Graco
Dirección General de Investigaciones Oceanográficas y cambio Climático, Instituto del Mar del Perú (IMARPE), P.O. Box 22, Callao, Perú
Xiao Ma
GEOMAR Helmholtz Centre of Ocean Research Kiel, Kiel, 24105, Germany
Damian L. Arévalo-Martínez
GEOMAR Helmholtz Centre of Ocean Research Kiel, Kiel, 24105, Germany
Damian S. Grundle
GEOMAR Helmholtz Centre of Ocean Research Kiel, Kiel, 24105, Germany
Bermuda Institute of Ocean Sciences, St. George's, GE01, Bermuda
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Claudia Frey, Hermann W. Bange, Eric P. Achterberg, Amal Jayakumar, Carolin R. Löscher, Damian L. Arévalo-Martínez, Elizabeth León-Palmero, Mingshuang Sun, Xin Sun, Ruifang C. Xie, Sergey Oleynik, and Bess B. Ward
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Carolin R. Löscher, Wiebke Mohr, Hermann W. Bange, and Donald E. Canfield
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Ye Tian, Gui-Peng Yang, Chun-Ying Liu, Pei-Feng Li, Hong-Tao Chen, and Hermann W. Bange
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Ye Tian, Chao Xue, Chun-Ying Liu, Gui-Peng Yang, Pei-Feng Li, Wei-Hua Feng, and Hermann W. Bange
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Hermann W. Bange, Chun Hock Sim, Daniel Bastian, Jennifer Kallert, Annette Kock, Aazani Mujahid, and Moritz Müller
Biogeosciences, 16, 4321–4335, https://doi.org/10.5194/bg-16-4321-2019, https://doi.org/10.5194/bg-16-4321-2019, 2019
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Xiao Ma, Sinikka T. Lennartz, and Hermann W. Bange
Biogeosciences, 16, 4097–4111, https://doi.org/10.5194/bg-16-4097-2019, https://doi.org/10.5194/bg-16-4097-2019, 2019
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Eric J. Morgan, Jost V. Lavric, Damian L. Arévalo-Martínez, Hermann W. Bange, Tobias Steinhoff, Thomas Seifert, and Martin Heimann
Biogeosciences, 16, 4065–4084, https://doi.org/10.5194/bg-16-4065-2019, https://doi.org/10.5194/bg-16-4065-2019, 2019
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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.
Catherine A. Pfister and Mark A. Altabet
Biogeosciences, 16, 193–206, https://doi.org/10.5194/bg-16-193-2019, https://doi.org/10.5194/bg-16-193-2019, 2019
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Microbial assemblages on host plants and animals are an increasingly recognized biological phenomenon. We present evidence that microbes in association with mussels and seaweeds are contributing greatly to nitrogen cycling in coastal marine areas, often many times that of the microbes that are simply free-living in seawater. The addition of dissolved organic carbon increased nutrient uptake by microbes, suggesting that coastal species enhance microbial metabolism through resource provisioning.
Qixing Ji, Claudia Frey, Xin Sun, Melanie Jackson, Yea-Shine Lee, Amal Jayakumar, Jeffrey C. Cornwell, and Bess B. Ward
Biogeosciences, 15, 6127–6138, https://doi.org/10.5194/bg-15-6127-2018, https://doi.org/10.5194/bg-15-6127-2018, 2018
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Nitrous oxide (N2O) is a strong greenhouse gas and ozone-depletion agent. Intense N2O effluxes had been observed from nutrient-rich estuaries with human impacts, such as the Chesapeake Bay. We report that increased nitrogen availability and low-oxygen conditions stimulate N2O production. Thus, controlling the nutrient input to the bay will decrease nitrogen availability and alleviate eutrophication, leading to water column reoxygenation, and subsequently will mitigate N2O emission.
Samuel T. Wilson, Hermann W. Bange, Damian L. Arévalo-Martínez, Jonathan Barnes, Alberto V. Borges, Ian Brown, John L. Bullister, Macarena Burgos, David W. Capelle, Michael Casso, Mercedes de la Paz, Laura Farías, Lindsay Fenwick, Sara Ferrón, Gerardo Garcia, Michael Glockzin, David M. Karl, Annette Kock, Sarah Laperriere, Cliff S. Law, Cara C. Manning, Andrew Marriner, Jukka-Pekka Myllykangas, John W. Pohlman, Andrew P. Rees, Alyson E. Santoro, Philippe D. Tortell, Robert C. Upstill-Goddard, David P. Wisegarver, Gui-Ling Zhang, and Gregor Rehder
Biogeosciences, 15, 5891–5907, https://doi.org/10.5194/bg-15-5891-2018, https://doi.org/10.5194/bg-15-5891-2018, 2018
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To determine the variability between independent measurements of dissolved methane and nitrous oxide, seawater samples were analyzed by multiple laboratories. The results revealed the influences of the different parts of the analytical process, from the initial sample collection to the calculation of the final concentrations. Recommendations are made to improve dissolved methane and nitrous oxide measurements to help preclude future analytical discrepancies between laboratories.
Johanna Maltby, Lea Steinle, Carolin R. Löscher, Hermann W. Bange, Martin A. Fischer, Mark Schmidt, and Tina Treude
Biogeosciences, 15, 137–157, https://doi.org/10.5194/bg-15-137-2018, https://doi.org/10.5194/bg-15-137-2018, 2018
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The activity and environmental controls of methanogenesis (MG) within the sulfate-reducing zone (0–30 cm below the seafloor) were investigated in organic-rich sediments of the seasonally hypoxic Eckernförde Bay, SW Baltic Sea. MG activity was mostly linked to non-competitive substrates. The major controls identified were organic matter availability, C / N, temperature, and O2 in the water column, revealing higher rates in warm, stratified, hypoxic seasons compared to colder, oxygenated seasons.
Eike E. Köhn, Sören Thomsen, Damian L. Arévalo-Martínez, and Torsten Kanzow
Ocean Sci., 13, 1017–1033, https://doi.org/10.5194/os-13-1017-2017, https://doi.org/10.5194/os-13-1017-2017, 2017
Michelle I. Graco, Sara Purca, Boris Dewitte, Carmen G. Castro, Octavio Morón, Jesús Ledesma, Georgina Flores, and Dimitri Gutiérrez
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The Peruvian coastal upwelling ecosystem is a natural laboratory to study climatic variability and climate change. We examined the variability in the OMZ in the last decades in connection with the equatorial Pacific strong 1997–1998 El Niño event and the influence of central Pacific El Niño events and enhanced equatorial Kelvin wave activity since 2000. The data reveal two contrasting regimes and a long-term trend corresponding to a deepening of the oxygen-deficient waters and warming.
Chun-Ying Liu, Wei-Hua Feng, Ye Tian, Gui-Peng Yang, Pei-Feng Li, and Hermann W. Bange
Ocean Sci., 13, 623–632, https://doi.org/10.5194/os-13-623-2017, https://doi.org/10.5194/os-13-623-2017, 2017
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We developed a new method for the determination of dissolved nitric oxide (NO) in discrete seawater samples based on the combination of a purge-and-trap setup and a fluorometric detection of NO. With this method we have a reliable and comparably easy to use method to measure oceanic NO surface concentrations, which can be used to decipher both its temporal and spatial distributions as well as its biogeochemical pathways in the oceans.
Lea Steinle, Johanna Maltby, Tina Treude, Annette Kock, Hermann W. Bange, Nadine Engbersen, Jakob Zopfi, Moritz F. Lehmann, and Helge Niemann
Biogeosciences, 14, 1631–1645, https://doi.org/10.5194/bg-14-1631-2017, https://doi.org/10.5194/bg-14-1631-2017, 2017
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Large amounts of methane are produced in anoxic, coastal sediments, from which it can seep into the overlying water column. Aerobic oxidation of methane (MOx) mediated by methanotrophic bacteria is an important sink for methane before its evasion to the atmosphere. In a 2-year seasonal study, we investigated the spatio-temporal variability of MOx in a seasonally hypoxic coastal inlet using radiotracer-based methods. In experiments, we assessed the effect of variable oxygen concentrations on MOx.
Sinikka T. Lennartz, Christa A. Marandino, Marc von Hobe, Pau Cortes, Birgit Quack, Rafel Simo, Dennis Booge, Andrea Pozzer, Tobias Steinhoff, Damian L. Arevalo-Martinez, Corinna Kloss, Astrid Bracher, Rüdiger Röttgers, Elliot Atlas, and Kirstin Krüger
Atmos. Chem. Phys., 17, 385–402, https://doi.org/10.5194/acp-17-385-2017, https://doi.org/10.5194/acp-17-385-2017, 2017
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We present new sea surface and marine boundary layer measurements of carbonyl sulfide, the most abundant sulfur gas in the atmosphere, and calculate an oceanic emission estimate. Our results imply that oceanic emissions are very unlikely to account for the missing source in the atmospheric budget that is currently discussed for OCS.
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.
Carolin R. Löscher, Hermann W. Bange, Ruth A. Schmitz, Cameron M. Callbeck, Anja Engel, Helena Hauss, Torsten Kanzow, Rainer Kiko, Gaute Lavik, Alexandra Loginova, Frank Melzner, Judith Meyer, Sven C. Neulinger, Markus Pahlow, Ulf Riebesell, Harald Schunck, Sören Thomsen, and Hannes Wagner
Biogeosciences, 13, 3585–3606, https://doi.org/10.5194/bg-13-3585-2016, https://doi.org/10.5194/bg-13-3585-2016, 2016
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The ocean loses oxygen due to climate change. Addressing this issue in tropical ocean regions (off Peru and Mauritania), we aimed to understand the effects of oxygen depletion on various aspects of marine biogeochemistry, including primary production and export production, the nitrogen cycle, greenhouse gas production, organic matter fluxes and remineralization, and the role of zooplankton and viruses.
Catherine A. Pfister, Mark A. Altabet, Santhiska Pather, and Greg Dwyer
Biogeosciences, 13, 3519–3531, https://doi.org/10.5194/bg-13-3519-2016, https://doi.org/10.5194/bg-13-3519-2016, 2016
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It is increasingly recognized that marine animals host microbes relevant to nitrogen cycling. Rocky shore tidepools host a phylogenetically diverse biota that inspired us to experimentally isolate their effects on microbial nitrogen processing. We found that mussels promote high rates and diverse types of microbial nitrogen metabolisms. We further developed a novel mathematical model that quantified these diverse processes and showed their significance to nitrogen processing.
Carolin R. Löscher, Annie Bourbonnais, Julien Dekaezemacker, Chawalit N. Charoenpong, Mark A. Altabet, Hermann W. Bange, Rena Czeschel, Chris Hoffmann, and Ruth Schmitz
Biogeosciences, 13, 2889–2899, https://doi.org/10.5194/bg-13-2889-2016, https://doi.org/10.5194/bg-13-2889-2016, 2016
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The ocean is full of eddies and they play a key role for ocean biogeochemistry. In order to understand dinitrogen (N2) fixation, one major control of oceanic primary production, we investigated three eddies in the eastern tropical South Pacific off Peru. We conducted the first detailed survey and found increased N2 fixation in the oxygen-depleted cores of anticyclonic mode water eddies. Taken together, we could – for the first time – show that eddies play an important role in N2 fixation off Peru.
Denise Müller, Hermann W. Bange, Thorsten Warneke, Tim Rixen, Moritz Müller, Aazani Mujahid, and Justus Notholt
Biogeosciences, 13, 2415–2428, https://doi.org/10.5194/bg-13-2415-2016, https://doi.org/10.5194/bg-13-2415-2016, 2016
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Estuaries act as sources of the greenhouse gases nitrous oxide (N2O) and methane (CH4) to the atmosphere. We provide first measurements of N2O and CH4 in two estuaries in north-western Borneo, a region which is dominated by peatlands. We show that N2O and CH4 concentrations in these estuaries are moderate despite high organic carbon loads, that nutrient enhancement does not lead to enhanced N2O emissions, and that the wet season dominates the variability of the emissions in these systems.
Happy Hu, Annie Bourbonnais, Jennifer Larkum, Hermann W. Bange, and Mark A. Altabet
Biogeosciences, 13, 1453–1468, https://doi.org/10.5194/bg-13-1453-2016, https://doi.org/10.5194/bg-13-1453-2016, 2016
Damian L. Arévalo-Martínez, Annette Kock, Carolin R. Löscher, Ruth A. Schmitz, Lothar Stramma, and Hermann W. Bange
Biogeosciences, 13, 1105–1118, https://doi.org/10.5194/bg-13-1105-2016, https://doi.org/10.5194/bg-13-1105-2016, 2016
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We present the first measurements of N2O across three mesoscale eddies in the eastern tropical South Pacific. Eddie's vertical structure, offshore transport, properties during its formation and near-surface primary production determined the N2O distribution. Substantial depletion of N2O within the core of anticyclonic eddies suggests that although these are transient features, N-loss processes within their centres can lead to an enhanced N2O sink which is not accounted for in marine N2O budgets.
A. Kock, D. L. Arévalo-Martínez, C. R. Löscher, and H. W. Bange
Biogeosciences, 13, 827–840, https://doi.org/10.5194/bg-13-827-2016, https://doi.org/10.5194/bg-13-827-2016, 2016
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We measured the nitrous oxide (N2O) distribution in the water column in the oxygen minimum zone off Peru, an area with extremely high N2O emissions. Our data show very variable and often very high N2O concentrations in the water column at the coast, which lead to high N2O emissions when these waters are brought to the surface. The very high N2O production off Peru may be caused by high nutrient turnover rates together with rapid changes in the oxygen concentrations.
A. R. Baker, M. Thomas, H. W. Bange, and E. Plasencia Sánchez
Biogeosciences, 13, 817–825, https://doi.org/10.5194/bg-13-817-2016, https://doi.org/10.5194/bg-13-817-2016, 2016
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Concentrations of major ions and trace metals were measured in aerosols off the coast of Peru in December 2012. A few trace metals (iron, copper, nickel, and cobalt) had anomalously high concentrations, which may be associated with industrial metal smelting activities in the region. The atmosphere appears to supply an excess of iron (relative to atmospheric nitrogen supply) to the phytoplankton community of the Peruvian upwelling system.
D. Müller, T. Warneke, T. Rixen, M. Müller, A. Mujahid, H. W. Bange, and J. Notholt
Biogeosciences, 13, 691–705, https://doi.org/10.5194/bg-13-691-2016, https://doi.org/10.5194/bg-13-691-2016, 2016
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We studied organic carbon and the dissolved greenhouse gases carbon dioxide (CO2) and carbon monoxide (CO) in two estuaries in Sarawak, Malaysia, whose coast is covered by carbon-rich peatlands. The estuaries received terrestrial organic carbon from peat-draining tributaries. A large fraction was converted to CO2 and a minor fraction to CO. Both gases were released to the atmosphere. This shows how these estuaries function as efficient filters between land and ocean in this important region.
H. E. Lutterbeck and H. W. Bange
Ocean Sci., 11, 937–946, https://doi.org/10.5194/os-11-937-2015, https://doi.org/10.5194/os-11-937-2015, 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.
S. T. Lennartz, A. Lehmann, J. Herrford, F. Malien, H.-P. Hansen, H. Biester, and H. W. Bange
Biogeosciences, 11, 6323–6339, https://doi.org/10.5194/bg-11-6323-2014, https://doi.org/10.5194/bg-11-6323-2014, 2014
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A time series of nine oceanic parameters from the coastal time series station Boknis Eck (BE, southwestern Baltic Sea) in the period of 1957-2013 is analysed with respect to seasonal cycles and long-term trends. Most striking was a paradoxical decreasing trend in oxygen with a simultaneous decline in eutrophication. Possible reasons for this paradox, e.g. processes related to warming temperatures such as increased decomposition of organic matter or altered ventilation, are discussed.
P. K. Swart, S. Evans, T. Capo, and M. A. Altabet
Biogeosciences, 11, 6147–6157, https://doi.org/10.5194/bg-11-6147-2014, https://doi.org/10.5194/bg-11-6147-2014, 2014
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The ratio of nitrogen-15 to nitrogen-14 of macroalgae has been termed the DNA of sewage. Higher amounts of N-15 have been suggested to indicate the influence of sewage-derived N. But what exactly does the ratio of 15N/14N record?
We found that the nitrogen isotopic ratio was dependent upon not only the value in the water but also its concentration of nitrate. At low concentration there was little fractionation, but at higher values the uptake by algae left more of the N-15 in the water.
J. Friedrich, F. Janssen, D. Aleynik, H. W. Bange, N. Boltacheva, M. N. Çagatay, A. W. Dale, G. Etiope, Z. Erdem, M. Geraga, A. Gilli, M. T. Gomoiu, P. O. J. Hall, D. Hansson, Y. He, M. Holtappels, M. K. Kirf, M. Kononets, S. Konovalov, A. Lichtschlag, D. M. Livingstone, G. Marinaro, S. Mazlumyan, S. Naeher, R. P. North, G. Papatheodorou, O. Pfannkuche, R. Prien, G. Rehder, C. J. Schubert, T. Soltwedel, S. Sommer, H. Stahl, E. V. Stanev, A. Teaca, A. Tengberg, C. Waldmann, B. Wehrli, and F. Wenzhöfer
Biogeosciences, 11, 1215–1259, https://doi.org/10.5194/bg-11-1215-2014, https://doi.org/10.5194/bg-11-1215-2014, 2014
D. L. Arévalo-Martínez, M. Beyer, M. Krumbholz, I. Piller, A. Kock, T. Steinhoff, A. Körtzinger, and H. W. Bange
Ocean Sci., 9, 1071–1087, https://doi.org/10.5194/os-9-1071-2013, https://doi.org/10.5194/os-9-1071-2013, 2013
L. Stramma, H. W. Bange, R. Czeschel, A. Lorenzo, and M. Frank
Biogeosciences, 10, 7293–7306, https://doi.org/10.5194/bg-10-7293-2013, https://doi.org/10.5194/bg-10-7293-2013, 2013
I.-N. Kim, K. Lee, H. W. Bange, and A. M. Macdonald
Biogeosciences, 10, 6783–6792, https://doi.org/10.5194/bg-10-6783-2013, https://doi.org/10.5194/bg-10-6783-2013, 2013
C. A. Marandino, S. Tegtmeier, K. Krüger, C. Zindler, E. L. Atlas, F. Moore, and H. W. Bange
Atmos. Chem. Phys., 13, 8427–8437, https://doi.org/10.5194/acp-13-8427-2013, https://doi.org/10.5194/acp-13-8427-2013, 2013
K. Laß, H. W. Bange, and G. Friedrichs
Biogeosciences, 10, 5325–5334, https://doi.org/10.5194/bg-10-5325-2013, https://doi.org/10.5194/bg-10-5325-2013, 2013
C. Zindler, A. Bracher, C. A. Marandino, B. Taylor, E. Torrecilla, A. Kock, and H. W. Bange
Biogeosciences, 10, 3297–3311, https://doi.org/10.5194/bg-10-3297-2013, https://doi.org/10.5194/bg-10-3297-2013, 2013
E. Montes, M. A. Altabet, F. E. Muller-Karger, M. I. Scranton, R. C. Thunell, C. Benitez-Nelson, L. Lorenzoni, and Y. M. Astor
Biogeosciences, 10, 267–279, https://doi.org/10.5194/bg-10-267-2013, https://doi.org/10.5194/bg-10-267-2013, 2013
L. M. Zamora, A. Oschlies, H. W. Bange, K. B. Huebert, J. D. Craig, A. Kock, and C. R. Löscher
Biogeosciences, 9, 5007–5022, https://doi.org/10.5194/bg-9-5007-2012, https://doi.org/10.5194/bg-9-5007-2012, 2012
Related subject area
Biogeochemistry: Open Ocean
An upper-mesopelagic-zone carbon budget for the subarctic North Pacific
Ocean alkalinity enhancement in an open-ocean ecosystem: biogeochemical responses and carbon storage durability
Relationships between the concentration of particulate organic nitrogen and the inherent optical properties of seawater in oceanic surface waters
Inadequacies in the representation of sub-seasonal phytoplankton dynamics in Earth system models
Nitrogen dynamics and nitrate stable isotopes indicate nitrogen loss in the Bay of Bengal
Composite model-based estimate of the ocean carbon sink from 1959 to 2022
Phytoplankton community structure in relation to iron and macronutrient fluxes from subsurface waters in the western North Pacific during summer
Intense and localized export of selected marine snow types at eddy edges in the South Atlantic Ocean
Spatial distributions of iron and manganese in surface waters of the Arctic's Laptev and East Siberian seas
Climate-driven shifts in Southern Ocean primary producers and biogeochemistry in CMIP6 models
Oceanic enrichment of ammonium and its impacts on phytoplankton community composition under a high-emissions scenario
Ocean acidification trends and carbonate system dynamics across the North Atlantic subpolar gyre water masses during 2009–2019
Pelagic coccolithophore production and dissolution and their impacts on particulate inorganic carbon cycling in the western North Pacific
Marine snow morphology drives sinking and attenuation in the ocean interior
Sedimentary organic matter signature hints at the phytoplankton-driven biological carbon pump in the central Arabian Sea
Hydrological cycle amplification imposes spatial patterns on the climate change response of ocean pH and carbonate chemistry
Assessing the tropical Atlantic biogeochemical processes in the Norwegian Earth System Model
Evolution of oxygen and stratification and their relationship in the North Pacific Ocean in CMIP6 Earth system models
Evaluation of CMIP6 model performance in simulating historical biogeochemistry across the southern South China Sea
Drivers of decadal trends in the ocean carbon sink in the past, present, and future in Earth system models
Anthropogenic carbon storage and its decadal changes in the Atlantic between 1990–2020
Ocean alkalinity enhancement impacts: regrowth of marine microalgae in alkaline mineral concentrations simulating the initial concentrations after ship-based dispersions
Climatic controls on metabolic constraints in the ocean
Effects of grain size and seawater salinity on magnesium hydroxide dissolution and secondary calcium carbonate precipitation kinetics: implications for ocean alkalinity enhancement
Short-term response of Emiliania huxleyi growth and morphology to abrupt salinity stress
Assessing the impact of CO2-equilibrated ocean alkalinity enhancement on microbial metabolic rates in an oligotrophic system
A time series analysis of transparent exopolymer particle distributions and C:N stoichiometry in the subtropical North Pacific: a key process in net community production and preformed nitrate anomalies?
Phosphomonoesterase and phosphodiesterase activities in the eastern Mediterranean in two contrasting seasonal situations
Net primary production annual maxima in the North Atlantic projected to shift in the 21st century
Testing the influence of light on nitrite cycling in the eastern tropical North Pacific
Loss of nitrogen via anaerobic ammonium oxidation (anammox) in the California Current system during the late Quaternary
Technical note: Assessment of float pH data quality control methods – a case study in the subpolar northwest Atlantic Ocean
Linking northeastern North Pacific oxygen changes to upstream surface outcrop variations
Underestimation of multi-decadal global O2 loss due to an optimal interpolation method
Reviews and syntheses: expanding the global coverage of gross primary production and net community production measurements using Biogeochemical-Argo floats
Characteristics of surface physical and biogeochemical parameters within mesoscale eddies in the Southern Ocean
Seasonal dynamics and annual budget of dissolved inorganic carbon in the northwestern Mediterranean deep-convection region
The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes
Reconstructing the ocean's mesopelagic zone carbon budget: sensitivity and estimation of parameters associated with prokaryotic remineralization
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
Brandon M. Stephens, Montserrat Roca-Martí, Amy E. Maas, Vinícius J. Amaral, Samantha Clevenger, Shawnee Traylor, Claudia R. Benitez-Nelson, Philip W. Boyd, Ken O. Buesseler, Craig A. Carlson, Nicolas Cassar, Margaret Estapa, Andrea J. Fassbender, Yibin Huang, Phoebe J. Lam, Olivier Marchal, Susanne Menden-Deuer, Nicola L. Paul, Alyson E. Santoro, David A. Siegel, and David P. Nicholson
Biogeosciences, 22, 3301–3328, https://doi.org/10.5194/bg-22-3301-2025, https://doi.org/10.5194/bg-22-3301-2025, 2025
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The ocean’s mesopelagic zone (MZ) plays a crucial role in the global carbon cycle. This study combines new and previously published measurements of organic carbon supply and demand collected in August 2018 in the MZ of the subarctic North Pacific Ocean. Supply was insufficient to meet demand in August, but supply entering into the MZ in the spring of 2018 could have met the August demand. Results suggest observations over seasonal timescales may help to close MZ carbon budgets.
Allanah Joy Paul, Mathias Haunost, Silvan Urs Goldenberg, Jens Hartmann, Nicolás Sánchez, Julieta Schneider, Niels Suitner, and Ulf Riebesell
Biogeosciences, 22, 2749–2766, https://doi.org/10.5194/bg-22-2749-2025, https://doi.org/10.5194/bg-22-2749-2025, 2025
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Ocean alkalinity enhancement (OAE) is being assessed for its potential to absorb atmospheric CO2 and store it for a long time. OAE still needs comprehensive assessment of its safety and effectiveness. We studied an idealised OAE application in a natural low-nutrient ecosystem over 1 month. Our results showed that biogeochemical functioning remained mostly stable but that the long-term capability for storing carbon may be limited at high alkalinity concentration.
Alain Fumenia, Hubert Loisel, Rick A. Reynolds, and Dariusz Stramski
Biogeosciences, 22, 2461–2484, https://doi.org/10.5194/bg-22-2461-2025, https://doi.org/10.5194/bg-22-2461-2025, 2025
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Particulate organic nitrogen (PON) plays a central role in ocean biogeochemistry, yet limited in situ data hinder a full understanding of PON variability and associated processes. Measurements of optical properties offer an alternative for assessing PON across diverse marine environments. Our analysis reveals strong relationships between PON and optical properties, supporting a promising means to assess PON from optical measurements performed in situ or conducted from remote-sensing platforms.
Madhavan Girijakumari Keerthi, Olivier Aumont, Lester Kwiatkowski, and Marina Levy
Biogeosciences, 22, 2163–2180, https://doi.org/10.5194/bg-22-2163-2025, https://doi.org/10.5194/bg-22-2163-2025, 2025
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We assessed how well climate models replicate sub-seasonal changes in ocean chlorophyll observed by satellites. Models struggle to capture these variations accurately. Some overestimate fluctuations and their impact on annual chlorophyll variability, while others underestimate them. The underestimation is likely due to limited model resolution, while the overestimation may come from internal model oscillations.
Gesa Schulz, Kirstin Dähnke, Tina Sanders, Jan Penopp, Hermann W. Bange, Rena Czeschel, and Birgit Gaye
EGUsphere, https://doi.org/10.5194/egusphere-2025-1660, https://doi.org/10.5194/egusphere-2025-1660, 2025
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Oxygen minimum zones (OMZs) are low-oxygen ocean areas that deplete nitrogen, a key marine nutrient. Understanding nitrogen cycling in OMZs is crucial for the global nitrogen cycle. This study examined nitrogen cycling in the OMZ of the Bay of Bengal and East Equatorial Indian Ocean, revealing limited mixing between both regions. Surface phytoplankton consumes nitrate, while deeper nitrification recycles nitrogen. In the BoB’s OMZ (100–300 m), nitrogen loss likely occurs via anammox.
Jens Terhaar
Biogeosciences, 22, 1631–1649, https://doi.org/10.5194/bg-22-1631-2025, https://doi.org/10.5194/bg-22-1631-2025, 2025
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The ocean is a major natural carbon sink. Despite its importance, estimates of the ocean carbon sink remain uncertain. Here, I present a hybrid model estimate of the ocean carbon sink from 1959 to 2022. By combining ocean models in hindcast mode and Earth system models, I keep the strength of each approach and remove the respective weaknesses. This composite model estimate is similar in magnitude to the best estimate of the Global Carbon Budget but 70 % less uncertain.
Huailin Deng, Koji Suzuki, Ichiro Yasuda, Hiroshi Ogawa, and Jun Nishioka
Biogeosciences, 22, 1495–1508, https://doi.org/10.5194/bg-22-1495-2025, https://doi.org/10.5194/bg-22-1495-2025, 2025
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Iron (Fe) and nitrate are vital for primary production in the North Pacific. Sedimentary Fe is carried by North Pacific Intermediate Water to the North Pacific, but the nutrient return path and its effect on phytoplankton are unclear. By combining Fe and macronutrient fluxes with phytoplankton composition, this study firstly revealed that Fe supply from the subsurface greatly controls diatom abundance and identified the nutrient return path in the subarctic gyre and Kuroshio–Oyashio transition area.
Alexandre Accardo, Rémi Laxenaire, Alberto Baudena, Sabrina Speich, Rainer Kiko, and Lars Stemmann
Biogeosciences, 22, 1183–1201, https://doi.org/10.5194/bg-22-1183-2025, https://doi.org/10.5194/bg-22-1183-2025, 2025
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The open ocean helps mitigate climate change by storing CO2 via the biological carbon pump (BCP), which involves processes like organic carbon production at the surface and transferring it to the deep ocean via various pathways. By deploying an autonomous platform, we found significant marine snow accumulation from the surface to the mesopelagic zone in frontal regions between eddies. We suggest that the coupling of hydrodynamics at eddy edges and biological activity may enhance this process.
Naoya Kanna, Kazutaka Tateyama, Takuji Waseda, Anna Timofeeva, Maria Papadimitraki, Laura Whitmore, Hajime Obata, Daiki Nomura, Hiroshi Ogawa, Youhei Yamashita, and Igor Polyakov
Biogeosciences, 22, 1057–1076, https://doi.org/10.5194/bg-22-1057-2025, https://doi.org/10.5194/bg-22-1057-2025, 2025
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This article presents data on iron and manganese, essential micronutrients for primary producers in the Arctic Laptev and East Siberian seas (LESS). There, observations were made through international cooperation with the Nansen and Amundsen Basin Observational System expedition during the late summer of 2021. The results from this study indicate that the major sources controlling the iron and manganese distributions on the LESS continental margins are river discharge and shelf sediment input.
Ben J. Fisher, Alex J. Poulton, Michael P. Meredith, Kimberlee Baldry, Oscar Schofield, and Sian F. Henley
Biogeosciences, 22, 975–994, https://doi.org/10.5194/bg-22-975-2025, https://doi.org/10.5194/bg-22-975-2025, 2025
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The Southern Ocean is a rapidly warming environment, with subsequent impacts on ecosystems and biogeochemical cycling. This study examines changes in phytoplankton and biogeochemistry using a range of climate models. Under climate change, the Southern Ocean will be warmer, more acidic and more productive and will have reduced nutrient availability by 2100. However, there is substantial variability between models across key productivity parameters. We propose ways of reducing this uncertainty.
Pearse J. Buchanan, Juan J. Pierella Karlusich, Robyn E. Tuerena, Roxana Shafiee, E. Malcolm S. Woodward, Chris Bowler, and Alessandro Tagliabue
EGUsphere, https://doi.org/10.5194/egusphere-2024-3639, https://doi.org/10.5194/egusphere-2024-3639, 2025
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Ammonium is a form of nitrogen that may become more important for growth of marine primary producers (i.e., phytoplankton) in the future. Because some phytoplankton taxa have a greater affinity for ammonium than others, the relative increase in ammonium could cause shifts in community composition. We quantify ammonium enrichment, identify its drivers, and isolate the possible effect on phytoplankton community composition under a high emissions scenario.
David Curbelo-Hernández, Fiz F. Pérez, Melchor González-Dávila, Sergey V. Gladyshev, Aridane G. González, David González-Santana, Antón Velo, Alexey Sokov, and J. Magdalena Santana-Casiano
Biogeosciences, 21, 5561–5589, https://doi.org/10.5194/bg-21-5561-2024, https://doi.org/10.5194/bg-21-5561-2024, 2024
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The study evaluated CO2–carbonate system dynamics in the North Atlantic subpolar gyre during 2009–2019. Significant ocean acidification, largely due to rising anthropogenic CO2 levels, was found. Cooling, freshening, and enhanced convective processes intensified this trend, affecting calcite and aragonite saturation. The findings contribute to a deeper understanding of ocean acidification and improve our knowledge about its impact on marine ecosystems.
Yuye Han, Zvi Steiner, Zhimian Cao, Di Fan, Junhui Chen, Jimin Yu, and Minhan Dai
EGUsphere, https://doi.org/10.5194/egusphere-2024-3492, https://doi.org/10.5194/egusphere-2024-3492, 2024
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Coccolithophore calcite accounts for a major fraction of particulate inorganic carbon (PIC) standing stocks in the western North Pacific, with a markedly higher contribution in the oligotrophic subtropical gyre than in the Kuroshio-Oyashio transition region, which highlights the importance of coccolithophores for PIC production in the pelagic ocean. We also found extensive dissolution of coccolithophore calcite in the oversaturated shallow waters primarily driven by microbial metabolic activity.
Yawouvi Dodji Soviadan, Miriam Beck, Joelle Habib, Alberto Baudena, Laetitia Drago, Alexandre Accardo, Remi Laxenaire, Sabrina Speich, Peter Brandt, Rainer Kiko, and Lars Stemmann
EGUsphere, https://doi.org/10.5194/egusphere-2024-3302, https://doi.org/10.5194/egusphere-2024-3302, 2024
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Key parameters representing the gravity flux in global models are the sinking speed and the vertical attenuation of the exported material. We calculate for the first time, these parameters in situ for 6 intermittent blooms followed by export events using high-resolution (3 days) time series of 0–1000 m depth profiles from imaging sensor mounted on an Argo float. We show that sinking speed depends not only on size but also on the morphology of the particles, density being an important property.
Medhavi Pandey, Haimanti Biswas, Daniel Birgel, Nicole Burdanowitz, and Birgit Gaye
Biogeosciences, 21, 4681–4698, https://doi.org/10.5194/bg-21-4681-2024, https://doi.org/10.5194/bg-21-4681-2024, 2024
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We analysed sea surface temperature (SST) proxy and plankton biomarkers in sediments that accumulate sinking material signatures from surface waters in the central Arabian Sea (21°–11° N, 64° E), a tropical basin impacted by monsoons. We saw a north–south SST gradient, and the biological proxies showed more organic matter from larger algae in the north. Smaller algae and zooplankton were more numerous in the south. These trends were related to ocean–atmospheric processes and oxygen availability.
Allison Hogikyan and Laure Resplandy
Biogeosciences, 21, 4621–4636, https://doi.org/10.5194/bg-21-4621-2024, https://doi.org/10.5194/bg-21-4621-2024, 2024
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Rising atmospheric CO2 influences ocean carbon chemistry, leading to ocean acidification. Global warming introduces spatial patterns in the intensity of ocean acidification. We show that the most prominent spatial patterns are controlled by warming-driven changes in rainfall and evaporation, not by the direct effect of warming on carbon chemistry and pH. These evaporation and rainfall patterns oppose acidification in saltier parts of the ocean and enhance acidification in fresher regions.
Shunya Koseki, Lander R. Crespo, Jerry Tjiputra, Filippa Fransner, Noel S. Keenlyside, and David Rivas
Biogeosciences, 21, 4149–4168, https://doi.org/10.5194/bg-21-4149-2024, https://doi.org/10.5194/bg-21-4149-2024, 2024
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We investigated how the physical biases of an Earth system model influence the marine biogeochemical processes in the tropical Atlantic. With four different configurations of the model, we have shown that the versions with better SST reproduction tend to better represent the primary production and air–sea CO2 flux in terms of climatology, seasonal cycle, and response to climate variability.
Lyuba Novi, Annalisa Bracco, Takamitsu Ito, and Yohei Takano
Biogeosciences, 21, 3985–4005, https://doi.org/10.5194/bg-21-3985-2024, https://doi.org/10.5194/bg-21-3985-2024, 2024
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We explored the relationship between oxygen and stratification in the North Pacific Ocean using a combination of data mining and machine learning. We used isopycnic potential vorticity (IPV) as an indicator to quantify ocean ventilation and analyzed its predictability, a strong O2–IPV connection, and predictability for IPV in the tropical Pacific. This opens new routes for monitoring ocean O2 through few observational sites co-located with more abundant IPV measurements in the tropical Pacific.
Winfred Marshal, Jing Xiang Chung, Nur Hidayah Roseli, Roswati Md Amin, and Mohd Fadzil Bin Mohd Akhir
Biogeosciences, 21, 4007–4035, https://doi.org/10.5194/bg-21-4007-2024, https://doi.org/10.5194/bg-21-4007-2024, 2024
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This study stands out for thoroughly examining CMIP6 ESMs' ability to simulate biogeochemical variables in the southern South China Sea, an economically important region. It assesses variables like chlorophyll, phytoplankton, nitrate, and oxygen on annual and seasonal scales. While global assessments exist, this study addresses a gap by objectively ranking 13 CMIP6 ocean biogeochemistry models' performance at a regional level, focusing on replicating specific observed biogeochemical variables.
Jens Terhaar
Biogeosciences, 21, 3903–3926, https://doi.org/10.5194/bg-21-3903-2024, https://doi.org/10.5194/bg-21-3903-2024, 2024
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Despite the ocean’s importance in the carbon cycle and hence the climate, observing the ocean carbon sink remains challenging. Here, I use an ensemble of 12 models to understand drivers of decadal trends of the past, present, and future ocean carbon sink. I show that 80 % of the decadal trends in the multi-model mean ocean carbon sink can be explained by changes in decadal trends in atmospheric CO2. The remaining 20 % are due to internal climate variability and ocean heat uptake.
Reiner Steinfeldt, Monika Rhein, and Dagmar Kieke
Biogeosciences, 21, 3839–3867, https://doi.org/10.5194/bg-21-3839-2024, https://doi.org/10.5194/bg-21-3839-2024, 2024
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We calculate the amount of anthropogenic carbon (Cant) in the Atlantic for the years 1990, 2000, 2010 and 2020. Cant is the carbon that is taken up by the ocean as a result of humanmade CO2 emissions. To determine the amount of Cant, we apply a technique that is based on the observations of other humanmade gases (e.g., chlorofluorocarbons). Regionally, changes in ocean ventilation have an impact on the storage of Cant. Overall, the increase in Cant is driven by the rising CO2 in the atmosphere.
Stephanie Delacroix, Tor Jensen Nystuen, August E. Dessen Tobiesen, Andrew L. King, and Erik Höglund
Biogeosciences, 21, 3677–3690, https://doi.org/10.5194/bg-21-3677-2024, https://doi.org/10.5194/bg-21-3677-2024, 2024
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The addition of alkaline minerals into the ocean might reduce excessive anthropogenic CO2 emissions. Magnesium hydroxide can be added in large amounts because of its low seawater solubility without reaching harmful pH levels. The toxicity effect results of magnesium hydroxide, by simulating the expected concentrations from a ship's dispersion scenario, demonstrated low impacts on both sensitive and local assemblages of marine microalgae when compared to calcium hydroxide.
Precious Mongwe, Matthew Long, Takamitsu Ito, Curtis Deutsch, and Yeray Santana-Falcón
Biogeosciences, 21, 3477–3490, https://doi.org/10.5194/bg-21-3477-2024, https://doi.org/10.5194/bg-21-3477-2024, 2024
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We use a collection of measurements that capture the physiological sensitivity of organisms to temperature and oxygen and a CESM1 large ensemble to investigate how natural climate variations and climate warming will impact the ability of marine heterotrophic marine organisms to support habitats in the future. We find that warming and dissolved oxygen loss over the next several decades will reduce the volume of ocean habitats and will increase organisms' vulnerability to extremes.
Charly A. Moras, Tyler Cyronak, Lennart T. Bach, Renaud Joannes-Boyau, and Kai G. Schulz
Biogeosciences, 21, 3463–3475, https://doi.org/10.5194/bg-21-3463-2024, https://doi.org/10.5194/bg-21-3463-2024, 2024
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We investigate the effects of mineral grain size and seawater salinity on magnesium hydroxide dissolution and calcium carbonate precipitation kinetics for ocean alkalinity enhancement. Salinity did not affect the dissolution, but calcium carbonate formed earlier at lower salinities due to the lower magnesium and dissolved organic carbon concentrations. Smaller grain sizes dissolved faster but calcium carbonate precipitated earlier, suggesting that medium grain sizes are optimal for kinetics.
Rosie M. Sheward, Christina Gebühr, Jörg Bollmann, and Jens O. Herrle
Biogeosciences, 21, 3121–3141, https://doi.org/10.5194/bg-21-3121-2024, https://doi.org/10.5194/bg-21-3121-2024, 2024
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How quickly do marine microorganisms respond to salinity stress? Our experiments with the calcifying marine plankton Emiliania huxleyi show that growth and cell morphology responded to salinity stress within as little as 24–48 hours, demonstrating that morphology and calcification are sensitive to salinity over a range of timescales. Our results have implications for understanding the short-term role of E. huxleyi in biogeochemical cycles and in size-based paleoproxies for salinity.
Laura Marín-Samper, Javier Arístegui, Nauzet Hernández-Hernández, Joaquín Ortiz, Stephen D. Archer, Andrea Ludwig, and Ulf Riebesell
Biogeosciences, 21, 2859–2876, https://doi.org/10.5194/bg-21-2859-2024, https://doi.org/10.5194/bg-21-2859-2024, 2024
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Our planet is facing a climate crisis. Scientists are working on innovative solutions that will aid in capturing the hard to abate emissions before it is too late. Exciting research reveals that ocean alkalinity enhancement, a key climate change mitigation strategy, does not harm phytoplankton, the cornerstone of marine ecosystems. Through meticulous study, we may have uncovered a positive relationship: up to a specific limit, enhancing ocean alkalinity boosts photosynthesis by certain species.
Kieran Curran, Tracy Villareal, and Robert T. Letscher
EGUsphere, https://doi.org/10.5194/egusphere-2024-1416, https://doi.org/10.5194/egusphere-2024-1416, 2024
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This work provides a two year record of marine organic gel concentrations from an open ocean site in the subtropical North Pacific Ocean north of Hawaii. These microscopic gels are investigated to understand their importance as an understudied component of organic matter cycling by marine microbes. We find an important role for gel cycling during the summer months, helping explain previously contradictory estimates of nutrient supply and demand for the subtropical ocean.
France Van Wambeke, Pascal Conan, Mireille Pujo-Pay, Vincent Taillandier, Olivier Crispi, Alexandra Pavlidou, Sandra Nunige, Morgane Didry, Christophe Salmeron, and Elvira Pulido-Villena
Biogeosciences, 21, 2621–2640, https://doi.org/10.5194/bg-21-2621-2024, https://doi.org/10.5194/bg-21-2621-2024, 2024
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Phosphomonoesterase (PME) and phosphodiesterase (PDE) activities over the epipelagic zone are described in the eastern Mediterranean Sea in winter and autumn. The types of concentration kinetics obtained for PDE (saturation at 50 µM, high Km, high turnover times) compared to those of PME (saturation at 1 µM, low Km, low turnover times) are discussed in regard to the possible inequal distribution of PDE and PME in the size continuum of organic material and accessibility to phosphodiesters.
Jenny Hieronymus, Magnus Hieronymus, Matthias Gröger, Jörg Schwinger, Raffaele Bernadello, Etienne Tourigny, Valentina Sicardi, Itzel Ruvalcaba Baroni, and Klaus Wyser
Biogeosciences, 21, 2189–2206, https://doi.org/10.5194/bg-21-2189-2024, https://doi.org/10.5194/bg-21-2189-2024, 2024
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The timing of the net primary production annual maxima in the North Atlantic in the period 1750–2100 is investigated using two Earth system models and the high-emissions scenario SSP5-8.5. It is found that, for most of the region, the annual maxima occur progressively earlier, with the most change occurring after the year 2000. Shifts in the seasonality of the primary production may impact the entire ecosystem, which highlights the need for long-term monitoring campaigns in this area.
Nicole M. Travis, Colette L. Kelly, and Karen L. Casciotti
Biogeosciences, 21, 1985–2004, https://doi.org/10.5194/bg-21-1985-2024, https://doi.org/10.5194/bg-21-1985-2024, 2024
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We conducted experimental manipulations of light level on microbial communities from the primary nitrite maximum. Overall, while individual microbial processes have different directions and magnitudes in their response to increasing light, the net community response is a decline in nitrite production with increasing light. We conclude that while increased light may decrease net nitrite production, high-light conditions alone do not exclude nitrification from occurring in the surface ocean.
Zoë Rebecca van Kemenade, Zeynep Erdem, Ellen Christine Hopmans, Jaap Smede Sinninghe Damsté, and Darci Rush
Biogeosciences, 21, 1517–1532, https://doi.org/10.5194/bg-21-1517-2024, https://doi.org/10.5194/bg-21-1517-2024, 2024
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The California Current system (CCS) hosts the eastern subtropical North Pacific oxygen minimum zone (ESTNP OMZ). This study shows anaerobic ammonium oxidizing (anammox) bacteria cause a loss of bioavailable nitrogen (N) in the ESTNP OMZ throughout the late Quaternary. Anammox occurred during both glacial and interglacial periods and was driven by the supply of organic matter and changes in ocean currents. These findings may have important consequences for biogeochemical models of the CCS.
Cathy Wimart-Rousseau, Tobias Steinhoff, Birgit Klein, Henry Bittig, and Arne Körtzinger
Biogeosciences, 21, 1191–1211, https://doi.org/10.5194/bg-21-1191-2024, https://doi.org/10.5194/bg-21-1191-2024, 2024
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The marine CO2 system can be measured independently and continuously by BGC-Argo floats since numerous pH sensors have been developed to suit these autonomous measurements platforms. By applying the Argo correction routines to float pH data acquired in the subpolar North Atlantic Ocean, we report the uncertainty and lack of objective criteria associated with the choice of the reference method as well the reference depth for the pH correction.
Sabine Mecking and Kyla Drushka
Biogeosciences, 21, 1117–1133, https://doi.org/10.5194/bg-21-1117-2024, https://doi.org/10.5194/bg-21-1117-2024, 2024
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This study investigates whether northeastern North Pacific oxygen changes may be caused by surface density changes in the northwest as water moves along density horizons from the surface into the subsurface ocean. A correlation is found with a lag that about matches the travel time of water from the northwest to the northeast. Salinity is the main driver causing decadal changes in surface density, whereas salinity and temperature contribute about equally to long-term declining density trends.
Takamitsu Ito, Hernan E. Garcia, Zhankun Wang, Shoshiro Minobe, Matthew C. Long, Just Cebrian, James Reagan, Tim Boyer, Christopher Paver, Courtney Bouchard, Yohei Takano, Seth Bushinsky, Ahron Cervania, and Curtis A. Deutsch
Biogeosciences, 21, 747–759, https://doi.org/10.5194/bg-21-747-2024, https://doi.org/10.5194/bg-21-747-2024, 2024
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This study aims to estimate how much oceanic oxygen has been lost and its uncertainties. One major source of uncertainty comes from the statistical gap-filling methods. Outputs from Earth system models are used to generate synthetic observations where oxygen data are extracted from the model output at the location and time of historical oceanographic cruises. Reconstructed oxygen trend is approximately two-thirds of the true trend.
Robert W. Izett, Katja Fennel, Adam C. Stoer, and David P. Nicholson
Biogeosciences, 21, 13–47, https://doi.org/10.5194/bg-21-13-2024, https://doi.org/10.5194/bg-21-13-2024, 2024
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This paper provides an overview of the capacity to expand the global coverage of marine primary production estimates using autonomous ocean-going instruments, called Biogeochemical-Argo floats. We review existing approaches to quantifying primary production using floats, provide examples of the current implementation of the methods, and offer insights into how they can be better exploited. This paper is timely, given the ongoing expansion of the Biogeochemical-Argo array.
Qian Liu, Yingjie Liu, and Xiaofeng Li
Biogeosciences, 20, 4857–4874, https://doi.org/10.5194/bg-20-4857-2023, https://doi.org/10.5194/bg-20-4857-2023, 2023
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In the Southern Ocean, abundant eddies behave opposite to our expectations. That is, anticyclonic (cyclonic) eddies are cold (warm). By investigating the variations of physical and biochemical parameters in eddies, we find that abnormal eddies have unique and significant effects on modulating the parameters. This study fills a gap in understanding the effects of abnormal eddies on physical and biochemical parameters in the Southern Ocean.
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, 20, 4683–4710, https://doi.org/10.5194/bg-20-4683-2023, https://doi.org/10.5194/bg-20-4683-2023, 2023
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Deep convection plays a key role in the circulation, thermodynamics, and biogeochemical cycles in the Mediterranean Sea, considered to be a hotspot of biodiversity and climate change. In this study, we investigate the seasonal and annual budget of dissolved inorganic carbon in the deep-convection area of the northwestern Mediterranean Sea.
Daniela König and Alessandro Tagliabue
Biogeosciences, 20, 4197–4212, https://doi.org/10.5194/bg-20-4197-2023, https://doi.org/10.5194/bg-20-4197-2023, 2023
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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.
Chloé Baumas, Robin Fuchs, Marc Garel, Jean-Christophe Poggiale, Laurent Memery, Frédéric A. C. Le Moigne, and Christian Tamburini
Biogeosciences, 20, 4165–4182, https://doi.org/10.5194/bg-20-4165-2023, https://doi.org/10.5194/bg-20-4165-2023, 2023
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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 C exported vs. C 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 impacts 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.
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.
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Short summary
A strong El Niño event occurred in the Peruvian coastal region in 2015–2016, during which higher sea surface temperatures co-occurred with significantly lower sea-to-air fluxes of nitrous oxide, an important greenhouse gas and ozone depletion agent. Stratified water column during El Niño retained a larger amount of nitrous oxide that was produced via multiple microbial pathways; and intense nitrous oxide effluxes could occur when normal upwelling is resumed after El Niño.
A strong El Niño event occurred in the Peruvian coastal region in 2015–2016, during which...
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