Articles | Volume 18, issue 5
https://doi.org/10.5194/bg-18-1645-2021
© Author(s) 2021. 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-18-1645-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
09 Mar 2021
Research article |
| 09 Mar 2021
| 09 Mar 2021
Radium-228-derived ocean mixing and trace element inputs in the South Atlantic
Department of Earth Sciences, University of Oxford, Oxford, UK
Walter Geibert
Alfred Wegener Institute Helmholtz Centre for Polar and Marine
Research, Bremerhaven, Germany
E. Malcolm S. Woodward
Plymouth Marine Laboratory, Plymouth, UK
Neil J. Wyatt
Ocean and Earth Sciences, National Oceanography Centre,
Southampton, UK
Maeve C. Lohan
Ocean and Earth Sciences, National Oceanography Centre,
Southampton, UK
Eric P. Achterberg
Ocean and Earth Sciences, National Oceanography Centre,
Southampton, UK
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
Gideon M. Henderson
Department of Earth Sciences, University of Oxford, Oxford, UK
Related authors
No articles found.
Daniel Müller, Bo Liu, Walter Geibert, Moritz Holtappels, Lasse Sander, Elda Miramontes, Heidi Taubner, Susann Henkel, Kai-Uwe Hinrichs, Denise Bethke, Ingrid Dohrmann, and Sabine Kasten
Biogeosciences, 22, 2541–2567, https://doi.org/10.5194/bg-22-2541-2025, https://doi.org/10.5194/bg-22-2541-2025, 2025
Short summary
Short summary
Coastal and shelf sediments are the most important sinks for organic carbon (OC) on Earth. We produced a new high-resolution sediment and porewater data set from the Helgoland Mud Area (HMA), North Sea, to determine which depositional factors control the preservation of OC. The burial efficiency is highest in an area of high sedimentation and terrigenous OC. The HMA covers 0.09 % of the North Sea but accounts for 0.76 % of its OC accumulation, highlighting the importance of the depocentre.
Travis Mellett, Justine Albers, Alyson Santoro, Pascal Salaun, Joseph Resing, Wenhao Wang, Alistar Lough, Alessandro Tagliabue, Maeve Lohan, Randelle Bundy, and Kristen Buck
EGUsphere, https://doi.org/10.5194/egusphere-2025-1798, https://doi.org/10.5194/egusphere-2025-1798, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
Short summary
Short summary
Hydrothermal plumes of iron have been observed to persist in the deep ocean, but the exact mechanisms that contribute to the long-range transport of iron is not well defined. We collected plume waters from three different vent systems along the mid-Atlantic Ridge and monitored the temporal evolution of the physical and chemical forms of iron and its interaction with organic matter over time to learn about the mechanisms that control its dispersion.
Frank Förster, Sebastian Flöter, Lucie Sauzéat, Stéphanie Reynaud, Eric Achterberg, Alexandra Tsay, Christine Ferrier-Pagès, and Tom E. Sheldrake
EGUsphere, https://doi.org/10.5194/egusphere-2025-1713, https://doi.org/10.5194/egusphere-2025-1713, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
Short summary
Short summary
Explosive volcanic eruptions produce ash that, upon ocean deposition, alters seawater chemistry by leaching or adsorbing metals. Corals like Stylophora pistillata incorporate these metals in its various compartments (tissue, symbionts and skeleton), with most metal changes appearing in the coral skeleton. We present a novel dataset of ash-seawater leaching results, trace metal analysis in the different coral compartments from cultured corals maintained under a control and ash exposed condition.
Noelle A. Held, Korrina Kunde, Clare E. Davis, Neil J. Wyatt, Elizabeth L. Mann, E. Malcolm S. Woodward, Matthew McIlvin, Alessandro Tagliabue, Benjamin S. Twining, Claire Mahaffey, Mak A. Saito, and Maeve C. Lohan
EGUsphere, https://doi.org/10.5194/egusphere-2024-3996, https://doi.org/10.5194/egusphere-2024-3996, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
Short summary
Short summary
Microbial enzymes are critical to marine biogeochemical cycles, but which microbes are producing those enzymes? We used a targeted proteomics method to quantify how much Prochlorococcus and Synechococcus contribute to surface ocean alkaline phosphatase activity. We find that alkaline phosphatase abundance is limited by the availability of iron, zinc and cobalt (which may substitute for zinc).
Claire Mahaffey, Noelle Held, Korinne Kunde, Clare Davis, Neil Wyatt, Matthew McIlvin, Malcolm Woodward, Lewis Wrightson, Alessandro Tagliabue, Maeve Lohan, and Mak Saito
EGUsphere, https://doi.org/10.5194/egusphere-2024-3987, https://doi.org/10.5194/egusphere-2024-3987, 2025
Short summary
Short summary
Picocyanobacteria fix over 50 % of carbon in the subtropical ocean, but which nutrients control their growth and activity? Using a states, rates and metaproteomic approach alongside targeted proteomics in experiments, we reveal picocyanobacteria are phosphorus stressed in the west Atlantic and nitrogen stressed in east Atlantic. We find evidence for trace metal and organic phosphorus control on alkaline phosphatase activity.
Wee Wei Khoo, Juliane Müller, Oliver Esper, Wenshen Xiao, Christian Stepanek, Paul Gierz, Gerrit Lohmann, Walter Geibert, Jens Hefter, and Gesine Mollenhauer
Clim. Past, 21, 299–326, https://doi.org/10.5194/cp-21-299-2025, https://doi.org/10.5194/cp-21-299-2025, 2025
Short summary
Short summary
Using a multiproxy approach, we analyzed biomarkers and diatom assemblages from a marine sediment core from the Powell Basin, Weddell Sea. The results reveal the first continuous coastal Antarctic sea ice record since the Last Penultimate Glacial. Our findings contribute valuable insights into past glacial–interglacial sea ice responses to a changing climate and enhance our understanding of ocean–sea ice–ice shelf interactions and dynamics.
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
Short summary
Short summary
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.
Jana Krause, Dustin Carroll, Juan Höfer, Jeremy Donaire, Eric P. Achterberg, Emilio Alarcón, Te Liu, Lorenz Meire, Kechen Zhu, and Mark J. Hopwood
The Cryosphere, 18, 5735–5752, https://doi.org/10.5194/tc-18-5735-2024, https://doi.org/10.5194/tc-18-5735-2024, 2024
Short summary
Short summary
Here we analysed calved ice samples from both the Arctic and Antarctic to assess the variability in the composition of iceberg meltwater. Our results suggest that low concentrations of nitrate and phosphate in ice are primarily from the ice matrix, whereas sediment-rich layers impart a low concentration of silica and modest concentrations of iron and manganese. At a global scale, there are very limited differences in the nutrient composition of ice.
Colleen L. Hoffman, Patrick J. Monreal, Justine B. Albers, Alastair J. M. Lough, Alyson E. Santoro, Travis Mellett, Kristen N. Buck, Alessandro Tagliabue, Maeve C. Lohan, Joseph A. Resing, and Randelle M. Bundy
Biogeosciences, 21, 5233–5246, https://doi.org/10.5194/bg-21-5233-2024, https://doi.org/10.5194/bg-21-5233-2024, 2024
Short summary
Short summary
Hydrothermally derived iron can be transported kilometers away from deep-sea vents, representing a significant flux of vital micronutrients to the ocean. However, the mechanisms that support the stabilization of dissolved iron remain elusive. Using electrochemical, spectrometry, and genomic methods, we demonstrated that strong ligands exert an important control on iron in plumes, and high-affinity iron-binding siderophores were identified in several hydrothermal plume samples for the first time.
Ingeborg Bussmann, Eric P. Achterberg, Holger Brix, Nicolas Brüggemann, Götz Flöser, Claudia Schütze, and Philipp Fischer
Biogeosciences, 21, 3819–3838, https://doi.org/10.5194/bg-21-3819-2024, https://doi.org/10.5194/bg-21-3819-2024, 2024
Short summary
Short summary
Methane (CH4) is an important greenhouse gas and contributes to climate warming. However, the input of CH4 from coastal areas to the atmosphere is not well defined. Dissolved and atmospheric CH4 was determined at high spatial resolution in or above the North Sea. The atmospheric CH4 concentration was mainly influenced by wind direction. With our detailed study on the spatial distribution of CH4 fluxes we were able to provide a detailed and more realistic estimation of coastal CH4 fluxes.
Stuart Umbo, Franziska Lechleitner, Thomas Opel, Sevasti Modestou, Tobias Braun, Anton Vaks, Gideon Henderson, Pete Scott, Alexander Osintzev, Alexandr Kononov, Irina Adrian, Yuri Dublyansky, Alena Giesche, and Sebastian Breitenbach
EGUsphere, https://doi.org/10.5194/egusphere-2024-1691, https://doi.org/10.5194/egusphere-2024-1691, 2024
Short summary
Short summary
We use cave rocks to reconstruct northern Siberian climate 8.68 ± 0.09 million years ago. We show that when global average temperature was about 4.5 °C warmer than today (similar to what’s expected in the coming decades should carbon emissions continue unabated), Arctic temperature increased by more than 18 °C. Similar levels of Arctic warming in the future would see huge areas of permafrost (permanently frozen ground) thaw and release greenhouse gases to the atmosphere.
Andrea J. McEvoy, Angus Atkinson, Ruth L. Airs, Rachel Brittain, Ian Brown, Elaine S. Fileman, Helen S. Findlay, Caroline L. McNeill, Clare Ostle, Tim J. Smyth, Paul J. Somerfield, Karen Tait, Glen A. Tarran, Simon Thomas, Claire E. Widdicombe, E. Malcolm S. Woodward, Amanda Beesley, David V. P. Conway, James Fishwick, Hannah Haines, Carolyn Harris, Roger Harris, Pierre Hélaouët, David Johns, Penelope K. Lindeque, Thomas Mesher, Abigail McQuatters-Gollop, Joana Nunes, Frances Perry, Ana M. Queiros, Andrew Rees, Saskia Rühl, David Sims, Ricardo Torres, and Stephen Widdicombe
Earth Syst. Sci. Data, 15, 5701–5737, https://doi.org/10.5194/essd-15-5701-2023, https://doi.org/10.5194/essd-15-5701-2023, 2023
Short summary
Short summary
Western Channel Observatory is an oceanographic time series and biodiversity reference site within 40 km of Plymouth (UK), sampled since 1903. Differing levels of reporting and formatting hamper the use of the valuable individual datasets. We provide the first summary database as monthly averages where comparisons can be made of the physical, chemical and biological data. We describe the database, illustrate its utility to examine seasonality and longer-term trends, and summarize previous work.
Kristian Spilling, Jonna Piiparinen, Eric P. Achterberg, Javier Arístegui, Lennart T. Bach, Maria T. Camarena-Gómez, Elisabeth von der Esch, Martin A. Fischer, Markel Gómez-Letona, Nauzet Hernández-Hernández, Judith Meyer, Ruth A. Schmitz, and Ulf Riebesell
Biogeosciences, 20, 1605–1619, https://doi.org/10.5194/bg-20-1605-2023, https://doi.org/10.5194/bg-20-1605-2023, 2023
Short summary
Short summary
We carried out an enclosure experiment using surface water off Peru with different additions of oxygen minimum zone water. In this paper, we report on enzyme activity and provide data on the decomposition of organic matter. We found very high activity with respect to an enzyme breaking down protein, suggesting that this is important for nutrient recycling both at present and in the future ocean.
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
Short summary
Short summary
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.
Helen Eri Amsler, Lena Mareike Thöle, Ingrid Stimac, Walter Geibert, Minoru Ikehara, Gerhard Kuhn, Oliver Esper, and Samuel Laurent Jaccard
Clim. Past, 18, 1797–1813, https://doi.org/10.5194/cp-18-1797-2022, https://doi.org/10.5194/cp-18-1797-2022, 2022
Short summary
Short summary
We present sedimentary redox-sensitive trace metal records from five sediment cores retrieved from the SW Indian Ocean. These records are indicative of oxygen-depleted conditions during cold periods and enhanced oxygenation during interstadials. Our results thus suggest that deep-ocean oxygenation changes were mainly controlled by ocean ventilation and that a generally more sluggish circulation contributed to sequestering remineralized carbon away from the atmosphere during glacial periods.
Shao-Min Chen, Ulf Riebesell, Kai G. Schulz, Elisabeth von der Esch, Eric P. Achterberg, and Lennart T. Bach
Biogeosciences, 19, 295–312, https://doi.org/10.5194/bg-19-295-2022, https://doi.org/10.5194/bg-19-295-2022, 2022
Short summary
Short summary
Oxygen minimum zones in the ocean are characterized by enhanced carbon dioxide (CO2) levels and are being further acidified by increasing anthropogenic atmospheric CO2. Here we report CO2 system measurements in a mesocosm study offshore Peru during a rare coastal El Niño event to investigate how CO2 dynamics may respond to ongoing ocean deoxygenation. Our observations show that nitrogen limitation, productivity, and plankton community shift play an important role in driving the CO2 dynamics.
Andrew J. Mason, Anton Vaks, Sebastian F. M. Breitenbach, John N. Hooker, and Gideon M. Henderson
Geochronology, 4, 33–54, https://doi.org/10.5194/gchron-4-33-2022, https://doi.org/10.5194/gchron-4-33-2022, 2022
Short summary
Short summary
A novel technique for the uranium–lead dating of geologically young carbonates is described and tested. The technique expands our ability to date geological events such as fault movements and past climate records.
Franziska A. Lechleitner, Christopher C. Day, Oliver Kost, Micah Wilhelm, Negar Haghipour, Gideon M. Henderson, and Heather M. Stoll
Clim. Past, 17, 1903–1918, https://doi.org/10.5194/cp-17-1903-2021, https://doi.org/10.5194/cp-17-1903-2021, 2021
Short summary
Short summary
Soil respiration is a critical but poorly constrained component of the global carbon cycle. We analyse the effect of changing soil respiration rates on the stable carbon isotope ratio of speleothems from northern Spain covering the last deglaciation. Using geochemical analysis and forward modelling we quantify the processes affecting speleothem stable carbon isotope ratios and extract a signature of increasing soil respiration synchronous with deglacial warming.
Kai G. Schulz, Eric P. Achterberg, Javier Arístegui, Lennart T. Bach, Isabel Baños, Tim Boxhammer, Dirk Erler, Maricarmen Igarza, Verena Kalter, Andrea Ludwig, Carolin Löscher, Jana Meyer, Judith Meyer, Fabrizio Minutolo, Elisabeth von der Esch, Bess B. Ward, and Ulf Riebesell
Biogeosciences, 18, 4305–4320, https://doi.org/10.5194/bg-18-4305-2021, https://doi.org/10.5194/bg-18-4305-2021, 2021
Short summary
Short summary
Upwelling of nutrient-rich deep waters to the surface make eastern boundary upwelling systems hot spots of marine productivity. This leads to subsurface oxygen depletion and the transformation of bioavailable nitrogen into inert N2. Here we quantify nitrogen loss processes following a simulated deep water upwelling. Denitrification was the dominant process, and budget calculations suggest that a significant portion of nitrogen that could be exported to depth is already lost in the surface ocean.
Neil J. Wyatt, Angela Milne, Eric P. Achterberg, Thomas J. Browning, Heather A. Bouman, E. Malcolm S. Woodward, and Maeve C. Lohan
Biogeosciences, 18, 4265–4280, https://doi.org/10.5194/bg-18-4265-2021, https://doi.org/10.5194/bg-18-4265-2021, 2021
Short summary
Short summary
Using data collected during two expeditions to the South Atlantic Ocean, we investigated how the interaction between external sources and biological activity influenced the availability of the trace metals zinc and cobalt. This is important as both metals play essential roles in the metabolism and growth of phytoplankton and thus influence primary productivity of the oceans. We found seasonal changes in both processes that helped explain upper-ocean trace metal cycling.
Maximiliano J. Vergara-Jara, Mark J. Hopwood, Thomas J. Browning, Insa Rapp, Rodrigo Torres, Brian Reid, Eric P. Achterberg, and José Luis Iriarte
Ocean Sci., 17, 561–578, https://doi.org/10.5194/os-17-561-2021, https://doi.org/10.5194/os-17-561-2021, 2021
Short summary
Short summary
Ash from the Calbuco 2015 eruption spread across northern Patagonia, the SE Pacific and the SW Atlantic. In the Pacific, a phytoplankton bloom corresponded closely to the volcanic ash plume, suggesting that ash fertilized this region of the ocean. No such fertilization was found in the Atlantic where nutrients plausibly supplied by ash were likely already in excess of phytoplankton demand. In Patagonia, the May bloom was more intense than usual, but the mechanistic link to ash was less clear.
Fuminori Hashihama, Hiroaki Saito, Taketoshi Kodama, Saori Yasui-Tamura, Jota Kanda, Iwao Tanita, Hiroshi Ogawa, E. Malcolm S. Woodward, Philip W. Boyd, and Ken Furuya
Biogeosciences, 18, 897–915, https://doi.org/10.5194/bg-18-897-2021, https://doi.org/10.5194/bg-18-897-2021, 2021
Short summary
Short summary
We investigated the nutrient assimilation characteristics of deep-water-induced phytoplankton blooms across the subtropical North and South Pacific Ocean. Nutrient drawdown ratios of dissolved inorganic nitrogen to phosphate were anomalously low in the western North Pacific, likely due to the high phosphate uptake capability of low-phosphate-adapted phytoplankton. The anomalous phosphate uptake might influence the maintenance of chronic phosphate depletion in the western North Pacific.
Maria-Elena Vorrath, Juliane Müller, Lorena Rebolledo, Paola Cárdenas, Xiaoxu Shi, Oliver Esper, Thomas Opel, Walter Geibert, Práxedes Muñoz, Christian Haas, Gerhard Kuhn, Carina B. Lange, Gerrit Lohmann, and Gesine Mollenhauer
Clim. Past, 16, 2459–2483, https://doi.org/10.5194/cp-16-2459-2020, https://doi.org/10.5194/cp-16-2459-2020, 2020
Short summary
Short summary
We tested the applicability of the organic biomarker IPSO25 for sea ice reconstructions in the industrial era at the western Antarctic Peninsula. We successfully evaluated our data with satellite sea ice observations. The comparison with marine and ice core records revealed that sea ice interpretations must consider climatic and sea ice dynamics. Sea ice biomarker production is mainly influenced by the Southern Annular Mode, while the El Niño–Southern Oscillation seems to have a minor impact.
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
Short summary
Short summary
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
Short summary
Short summary
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.
Lennart Thomas Bach, Allanah Joy Paul, Tim Boxhammer, Elisabeth von der Esch, Michelle Graco, Kai Georg Schulz, Eric Achterberg, Paulina Aguayo, Javier Arístegui, Patrizia Ayón, Isabel Baños, Avy Bernales, Anne Sophie Boegeholz, Francisco Chavez, Gabriela Chavez, Shao-Min Chen, Kristin Doering, Alba Filella, Martin Fischer, Patricia Grasse, Mathias Haunost, Jan Hennke, Nauzet Hernández-Hernández, Mark Hopwood, Maricarmen Igarza, Verena Kalter, Leila Kittu, Peter Kohnert, Jesus Ledesma, Christian Lieberum, Silke Lischka, Carolin Löscher, Andrea Ludwig, Ursula Mendoza, Jana Meyer, Judith Meyer, Fabrizio Minutolo, Joaquin Ortiz Cortes, Jonna Piiparinen, Claudia Sforna, Kristian Spilling, Sonia Sanchez, Carsten Spisla, Michael Sswat, Mabel Zavala Moreira, and Ulf Riebesell
Biogeosciences, 17, 4831–4852, https://doi.org/10.5194/bg-17-4831-2020, https://doi.org/10.5194/bg-17-4831-2020, 2020
Short summary
Short summary
The eastern boundary upwelling system off Peru is among Earth's most productive ocean ecosystems, but the factors that control its functioning are poorly constrained. Here we used mesocosms, moored ~ 6 km offshore Peru, to investigate how processes in plankton communities drive key biogeochemical processes. We show that nutrient and light co-limitation keep productivity and export at a remarkably constant level while stoichiometry changes strongly with shifts in plankton community structure.
Anna Plass, Christian Schlosser, Stefan Sommer, Andrew W. Dale, Eric P. Achterberg, and Florian Scholz
Biogeosciences, 17, 3685–3704, https://doi.org/10.5194/bg-17-3685-2020, https://doi.org/10.5194/bg-17-3685-2020, 2020
Short summary
Short summary
We compare the cycling of Fe and Cd in sulfidic sediments of the Peruvian oxygen minimum zone. Due to the contrasting solubility of their sulfide minerals, the sedimentary Fe release and Cd burial fluxes covary with spatial and temporal distributions of H2S. Depending on the solubility of their sulfide minerals, sedimentary trace metal fluxes will respond differently to ocean deoxygenation/expansion of H2S concentrations, which may change trace metal stoichiometry of upwelling water masses.
Noelle A. Held, Eric A. Webb, Matthew M. McIlvin, David A. Hutchins, Natalie R. Cohen, Dawn M. Moran, Korinna Kunde, Maeve C. Lohan, Claire Mahaffey, E. Malcolm S. Woodward, and Mak A. Saito
Biogeosciences, 17, 2537–2551, https://doi.org/10.5194/bg-17-2537-2020, https://doi.org/10.5194/bg-17-2537-2020, 2020
Short summary
Short summary
Trichodesmium is a globally important marine nitrogen fixer that stimulates primary production in the surface ocean. We surveyed metaproteomes of Trichodesmium populations across the North Atlantic and other oceans, and we found that they experience simultaneous phosphate and iron stress because of the biophysical limits of nutrient uptake. Importantly, nitrogenase was most abundant during co-stress, indicating the potential importance of this phenotype to global nitrogen and carbon cycling.
Mark J. Hopwood, Dustin Carroll, Thorben Dunse, Andy Hodson, Johnna M. Holding, José L. Iriarte, Sofia Ribeiro, Eric P. Achterberg, Carolina Cantoni, Daniel F. Carlson, Melissa Chierici, Jennifer S. Clarke, Stefano Cozzi, Agneta Fransson, Thomas Juul-Pedersen, Mie H. S. Winding, and Lorenz Meire
The Cryosphere, 14, 1347–1383, https://doi.org/10.5194/tc-14-1347-2020, https://doi.org/10.5194/tc-14-1347-2020, 2020
Short summary
Short summary
Here we compare and contrast results from five well-studied Arctic field sites in order to understand how glaciers affect marine biogeochemistry and marine primary production. The key questions are listed as follows. Where and when does glacial freshwater discharge promote or reduce marine primary production? How does spatio-temporal variability in glacial discharge affect marine primary production? And how far-reaching are the effects of glacial discharge on marine biogeochemistry?
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
Biogeosciences, 17, 2263–2287, https://doi.org/10.5194/bg-17-2263-2020, https://doi.org/10.5194/bg-17-2263-2020, 2020
Short summary
Short summary
The production of N2O via nitrification and denitrification associated with low-O2 waters is a major source of oceanic N2O. We investigated the regulation and dynamics of these processes with respect to O2 and organic matter inputs. The transcription of the key nitrification gene amoA rapidly responded to changes in O2 and strongly correlated with N2O production rates. N2O production by denitrification was clearly stimulated by organic carbon, implying that its supply controls N2O production.
Mark J. Hopwood, Nicolas Sanchez, Despo Polyviou, Øystein Leiknes, Julián Alberto Gallego-Urrea, Eric P. Achterberg, Murat V. Ardelan, Javier Aristegui, Lennart Bach, Sengul Besiktepe, Yohann Heriot, Ioanna Kalantzi, Tuba Terbıyık Kurt, Ioulia Santi, Tatiana M. Tsagaraki, and David Turner
Biogeosciences, 17, 1309–1326, https://doi.org/10.5194/bg-17-1309-2020, https://doi.org/10.5194/bg-17-1309-2020, 2020
Short summary
Short summary
Hydrogen peroxide, H2O2, is formed naturally in sunlight-exposed water by photochemistry. At high concentrations it is undesirable to biological cells because it is a stressor. Here, across a range of incubation experiments in diverse marine environments (Gran Canaria, the Mediterranean, Patagonia and Svalbard), we determine that two factors consistently affect the H2O2 concentrations irrespective of geographical location: bacteria abundance and experiment design.
Mark J. Hopwood, Carolina Santana-González, Julian Gallego-Urrea, Nicolas Sanchez, Eric P. Achterberg, Murat V. Ardelan, Martha Gledhill, Melchor González-Dávila, Linn Hoffmann, Øystein Leiknes, Juana Magdalena Santana-Casiano, Tatiana M. Tsagaraki, and David Turner
Biogeosciences, 17, 1327–1342, https://doi.org/10.5194/bg-17-1327-2020, https://doi.org/10.5194/bg-17-1327-2020, 2020
Short summary
Short summary
Fe is an essential micronutrient. Fe(III)-organic species are thought to account for > 99 % of dissolved Fe in seawater. Here we quantified Fe(II) during experiments in Svalbard, Gran Canaria, and Patagonia. Fe(II) was always a measurable fraction of dissolved Fe up to 65 %. Furthermore, when Fe(II) was allowed to decay in the dark, it remained present longer than predicted by kinetic equations, suggesting that Fe(II) is a more important fraction of dissolved Fe in seawater than widely recognized.
Ole Valk, Michiel M. Rutgers van der Loeff, Walter Geibert, Sandra Gdaniec, S. Bradley Moran, Kate Lepore, Robert Lawrence Edwards, Yanbin Lu, Viena Puigcorbé, Nuria Casacuberta, Ronja Paffrath, William Smethie, and Matthieu Roy-Barman
Ocean Sci., 16, 221–234, https://doi.org/10.5194/os-16-221-2020, https://doi.org/10.5194/os-16-221-2020, 2020
Short summary
Short summary
After 2007 230Th decreased significantly in the central Amundsen Basin. This decrease is accompanied by a circulation change, indicated by changes in salinity. Ventilation of waters is most likely not the reason for the observed depletion in 230Th as atmospherically derived tracers do not reveal an increase in ventilation rate. It is suggested that these interior waters have undergone enhanced scavenging of Th during transit from Fram Strait and the Barents Sea to the central Amundsen Basin.
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
Short summary
Short summary
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.
Jan-Lukas Menzel Barraqueta, Jessica K. Klar, Martha Gledhill, Christian Schlosser, Rachel Shelley, Hélène F. Planquette, Bernhard Wenzel, Geraldine Sarthou, and Eric P. Achterberg
Biogeosciences, 16, 1525–1542, https://doi.org/10.5194/bg-16-1525-2019, https://doi.org/10.5194/bg-16-1525-2019, 2019
Short summary
Short summary
We used surface water dissolved aluminium concentrations collected in four different GEOTRACES cruises to determine atmospheric deposition fluxes to the ocean. We calculate atmospheric deposition fluxes for largely under-sampled regions of the Atlantic Ocean and thus provide new constraints for models of atmospheric deposition. The use of the MADCOW model is of major importance as dissolved aluminium is analysed within the GEOTRACES project at high spatial resolution.
Feifei Deng, Gideon M. Henderson, Maxi Castrillejo, Fiz F. Perez, and Reiner Steinfeldt
Biogeosciences, 15, 7299–7313, https://doi.org/10.5194/bg-15-7299-2018, https://doi.org/10.5194/bg-15-7299-2018, 2018
Short summary
Short summary
To better use Pa / Th to reconstruct deep water ventilation rate, we assessed controls on 230Th and 231Pa in the northern North Atlantic. With extended optimum multi-parameter analysis and CFC-based water-mass age, we found the imprint of young overflow water on Th and Pa and enhanced scavenging near the seafloor. A significantly higher advective loss of Pa to the south relative to Th in the Atlantic was estimated, supporting the use of Pa / Th for assessing basin-scale meridional transport.
Géraldine Sarthou, Pascale Lherminier, Eric P. Achterberg, Fernando Alonso-Pérez, Eva Bucciarelli, Julia Boutorh, Vincent Bouvier, Edward A. Boyle, Pierre Branellec, Lidia I. Carracedo, Nuria Casacuberta, Maxi Castrillejo, Marie Cheize, Leonardo Contreira Pereira, Daniel Cossa, Nathalie Daniault, Emmanuel De Saint-Léger, Frank Dehairs, Feifei Deng, Floriane Desprez de Gésincourt, Jérémy Devesa, Lorna Foliot, Debany Fonseca-Batista, Morgane Gallinari, Maribel I. García-Ibáñez, Arthur Gourain, Emilie Grossteffan, Michel Hamon, Lars Eric Heimbürger, Gideon M. Henderson, Catherine Jeandel, Catherine Kermabon, François Lacan, Philippe Le Bot, Manon Le Goff, Emilie Le Roy, Alison Lefèbvre, Stéphane Leizour, Nolwenn Lemaitre, Pere Masqué, Olivier Ménage, Jan-Lukas Menzel Barraqueta, Herlé Mercier, Fabien Perault, Fiz F. Pérez, Hélène F. Planquette, Frédéric Planchon, Arnout Roukaerts, Virginie Sanial, Raphaëlle Sauzède, Catherine Schmechtig, Rachel U. Shelley, Gillian Stewart, Jill N. Sutton, Yi Tang, Nadine Tisnérat-Laborde, Manon Tonnard, Paul Tréguer, Pieter van Beek, Cheryl M. Zurbrick, and Patricia Zunino
Biogeosciences, 15, 7097–7109, https://doi.org/10.5194/bg-15-7097-2018, https://doi.org/10.5194/bg-15-7097-2018, 2018
Short summary
Short summary
The GEOVIDE cruise (GEOTRACES Section GA01) was conducted in the North Atlantic Ocean and Labrador Sea in May–June 2014. In this special issue, results from GEOVIDE, including physical oceanography and trace element and isotope cyclings, are presented among 17 articles. Here, the scientific context, project objectives, and scientific strategy of GEOVIDE are provided, along with an overview of the main results from the articles published in the special issue.
Jan-Lukas Menzel Barraqueta, Christian Schlosser, Hélène Planquette, Arthur Gourain, Marie Cheize, Julia Boutorh, Rachel Shelley, Leonardo Contreira Pereira, Martha Gledhill, Mark J. Hopwood, François Lacan, Pascale Lherminier, Geraldine Sarthou, and Eric P. Achterberg
Biogeosciences, 15, 5271–5286, https://doi.org/10.5194/bg-15-5271-2018, https://doi.org/10.5194/bg-15-5271-2018, 2018
Short summary
Short summary
In the North Atlantic and Labrador Sea, low aerosol deposition and enhanced primary productivity control the dissolved aluminium (dAl) surface distribution, while remineralization of particles seems to control the distribution at depth. DAl in the ocean allows us to indirectly quantify the amount of dust deposited to a given region for a given period. Hence, the study of its distribution, cycling, sources, and sinks is of major importance to improve aerosol deposition models and climate models.
Christian Schlosser, Katrin Schmidt, Alfred Aquilina, William B. Homoky, Maxi Castrillejo, Rachel A. Mills, Matthew D. Patey, Sophie Fielding, Angus Atkinson, and Eric P. Achterberg
Biogeosciences, 15, 4973–4993, https://doi.org/10.5194/bg-15-4973-2018, https://doi.org/10.5194/bg-15-4973-2018, 2018
Short summary
Short summary
Iron (Fe) emanating from the South Georgia shelf system fuels large phytoplankton blooms downstream of the island. However, the actual supply mechanisms of Fe are unclear. We found that shelf-sediment-derived iron and iron released from Antarctic krill control the Fe distribution in the shelf waters around South Georgia. The majority of the Fe appears to be derived from recycling of Fe-enriched particles that are transported with the water masses into the bloom region.
Amelie Driemel, Eberhard Fahrbach, Gerd Rohardt, Agnieszka Beszczynska-Möller, Antje Boetius, Gereon Budéus, Boris Cisewski, Ralph Engbrodt, Steffen Gauger, Walter Geibert, Patrizia Geprägs, Dieter Gerdes, Rainer Gersonde, Arnold L. Gordon, Hannes Grobe, Hartmut H. Hellmer, Enrique Isla, Stanley S. Jacobs, Markus Janout, Wilfried Jokat, Michael Klages, Gerhard Kuhn, Jens Meincke, Sven Ober, Svein Østerhus, Ray G. Peterson, Benjamin Rabe, Bert Rudels, Ursula Schauer, Michael Schröder, Stefanie Schumacher, Rainer Sieger, Jüri Sildam, Thomas Soltwedel, Elena Stangeew, Manfred Stein, Volker H Strass, Jörn Thiede, Sandra Tippenhauer, Cornelis Veth, Wilken-Jon von Appen, Marie-France Weirig, Andreas Wisotzki, Dieter A. Wolf-Gladrow, and Torsten Kanzow
Earth Syst. Sci. Data, 9, 211–220, https://doi.org/10.5194/essd-9-211-2017, https://doi.org/10.5194/essd-9-211-2017, 2017
Short summary
Short summary
Our oceans are always in motion – huge water masses are circulated by winds and by global seawater density gradients resulting from different water temperatures and salinities. Measuring temperature and salinity of the world's oceans is crucial e.g. to understand our climate. Since 1983, the research icebreaker Polarstern has been the basis of numerous water profile measurements in the Arctic and the Antarctic. We report on a unique collection of 33 years of polar salinity and temperature data.
Thomas Hornick, Lennart T. Bach, Katharine J. Crawfurd, Kristian Spilling, Eric P. Achterberg, Jason N. Woodhouse, Kai G. Schulz, Corina P. D. Brussaard, Ulf Riebesell, and Hans-Peter Grossart
Biogeosciences, 14, 1–15, https://doi.org/10.5194/bg-14-1-2017, https://doi.org/10.5194/bg-14-1-2017, 2017
Kristian Spilling, Kai G. Schulz, Allanah J. Paul, Tim Boxhammer, Eric P. Achterberg, Thomas Hornick, Silke Lischka, Annegret Stuhr, Rafael Bermúdez, Jan Czerny, Kate Crawfurd, Corina P. D. Brussaard, Hans-Peter Grossart, and Ulf Riebesell
Biogeosciences, 13, 6081–6093, https://doi.org/10.5194/bg-13-6081-2016, https://doi.org/10.5194/bg-13-6081-2016, 2016
Short summary
Short summary
We performed an experiment in the Baltic Sea in order to investigate the consequences of the increasing CO2 levels on biological processes in the free water mass. There was more accumulation of organic carbon at high CO2 levels. Surprisingly, this was caused by reduced loss processes (respiration and bacterial production) in a high-CO2 environment, and not by increased photosynthetic fixation of CO2. Our carbon budget can be used to better disentangle the effects of ocean acidification.
Allanah J. Paul, Eric P. Achterberg, Lennart T. Bach, Tim Boxhammer, Jan Czerny, Mathias Haunost, Kai-Georg Schulz, Annegret Stuhr, and Ulf Riebesell
Biogeosciences, 13, 3901–3913, https://doi.org/10.5194/bg-13-3901-2016, https://doi.org/10.5194/bg-13-3901-2016, 2016
Matthew P. Humphreys, Florence M. Greatrix, Eithne Tynan, Eric P. Achterberg, Alex M. Griffiths, Claudia H. Fry, Rebecca Garley, Alison McDonald, and Adrian J. Boyce
Earth Syst. Sci. Data, 8, 221–233, https://doi.org/10.5194/essd-8-221-2016, https://doi.org/10.5194/essd-8-221-2016, 2016
Short summary
Short summary
This paper reports the stable isotope composition of dissolved inorganic carbon in seawater for a transect from west to east across the North Atlantic Ocean. The results can be used to study oceanic uptake of anthropogenic carbon dioxide, and also to investigate the natural biological carbon pump. We also provide stable DIC isotope results for two batches of Dickson seawater CRMs to enable intercomparisons with other studies.
Monika Nausch, Lennart Thomas Bach, Jan Czerny, Josephine Goldstein, Hans-Peter Grossart, Dana Hellemann, Thomas Hornick, Eric Pieter Achterberg, Kai-Georg Schulz, and Ulf Riebesell
Biogeosciences, 13, 3035–3050, https://doi.org/10.5194/bg-13-3035-2016, https://doi.org/10.5194/bg-13-3035-2016, 2016
Short summary
Short summary
Studies investigating the effect of increasing CO2 levels on the phosphorus cycle in natural waters are lacking although phosphorus often controls phytoplankton development in aquatic systems. The aim of our study was to analyse effects of elevated CO2 levels on phosphorus pool sizes and uptake. Therefore, we conducted a CO2-manipulation mesocosm experiment in the Storfjärden (western Gulf of Finland, Baltic Sea) in summer 2012. We compared the phosphorus dynamics in different mesocosm treatment
A. J. Paul, L. T. Bach, K.-G. Schulz, T. Boxhammer, J. Czerny, E. P. Achterberg, D. Hellemann, Y. Trense, M. Nausch, M. Sswat, and U. Riebesell
Biogeosciences, 12, 6181–6203, https://doi.org/10.5194/bg-12-6181-2015, https://doi.org/10.5194/bg-12-6181-2015, 2015
Y. Zhang, N. Mahowald, R. A. Scanza, E. Journet, K. Desboeufs, S. Albani, J. F. Kok, G. Zhuang, Y. Chen, D. D. Cohen, A. Paytan, M. D. Patey, E. P. Achterberg, J. P. Engelbrecht, and K. W. Fomba
Biogeosciences, 12, 5771–5792, https://doi.org/10.5194/bg-12-5771-2015, https://doi.org/10.5194/bg-12-5771-2015, 2015
Short summary
Short summary
A new technique to determine a size-fractionated global soil elemental emission inventory based on a global soil and mineralogical data set is introduced. Spatial variability of mineral dust elemental fractions (8 elements, e.g., Ca, Fe, Al) is identified on a global scale, particularly for Ca. The Ca/Al ratio ranged between 0.1 and 5.0 and is confirmed as an indicator of dust source regions by a global dust model. Total and soluble dust element fluxes into different ocean basins are estimated.
M. P. Humphreys, E. P. Achterberg, A. M. Griffiths, A. McDonald, and A. J. Boyce
Earth Syst. Sci. Data, 7, 127–135, https://doi.org/10.5194/essd-7-127-2015, https://doi.org/10.5194/essd-7-127-2015, 2015
Short summary
Short summary
We present measurements of the stable carbon isotope composition of seawater dissolved inorganic carbon. The samples were collected during two research cruises in boreal summer 2012 in the northeastern Atlantic and Nordic Seas. The results can be used to investigate the marine carbon cycle, providing information about biological productivity and oceanic uptake of anthropogenic carbon dioxide.
T. J. Browning, H. A. Bouman, C. M. Moore, C. Schlosser, G. A. Tarran, E. M. S. Woodward, and G. M. Henderson
Biogeosciences, 11, 463–479, https://doi.org/10.5194/bg-11-463-2014, https://doi.org/10.5194/bg-11-463-2014, 2014
Related subject area
Biogeochemistry: Stable Isotopes & Other Tracers
Sea ice and mixed layer depth influence on nitrate depletion and associated isotopic effects in the Drake Passage–Weddell Sea region, Southern Ocean
Stable iron isotope signals indicate a “pseudo-abiotic” process driving deep iron release in methanic sediments
Triple oxygen isotope evidence for the pathway of nitrous oxide production in a forested soil with increased emission on rainy days
Previous integrated or organic farming affects productivity and ecosystem N balance rather than fertilizer 15N allocation to plants and soil, leaching, or gaseous emissions (NH3, N2O, and N2)
How long does carbon stay in a near-pristine central Amazon forest? An empirical estimate with radiocarbon
No increase is detected and modeled for the seasonal cycle amplitude of δ13C of atmospheric carbon dioxide
Fungi present distinguishable isotopic signals when grown on glycolytic versus tricarboxylic acid cycle intermediates
Bias in calculating gross nitrification rates in forested catchments using the triple oxygen isotopic composition (Δ17O) of stream nitrate
Position-specific kinetic isotope effects for nitrous oxide: a new expansion of the Rayleigh model
Technical note: A Bayesian mixing model to unravel isotopic data and quantify trace gas production and consumption pathways for time series data – Time-resolved FRactionation And Mixing Evaluation (TimeFRAME)
Separating above-canopy CO2 and O2 measurements into their atmospheric and biospheric signatures
Climatic controls on leaf wax hydrogen isotope ratios in terrestrial and marine sediments along a hyperarid-to-humid gradient
Fractionation of stable carbon isotopes during microbial propionate consumption in anoxic rice paddy soils
Sources and sinks of carbonyl sulfide inferred from tower and mobile atmospheric observations in the Netherlands
Downpour dynamics: outsized impacts of storm events on unprocessed atmospheric nitrate export in an urban watershed
The hidden role of dissolved organic carbon in the biogeochemical cycle of carbon in modern redox-stratified lakes
Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient
Partitioning of carbon export in the euphotic zone of the oligotrophic South China Sea
Determination of respiration and photosynthesis fractionation factors for atmospheric dioxygen inferred from a vegetation–soil–atmosphere analogue of the terrestrial biosphere in closed chambers
Permafrost degradation and nitrogen cycling in Arctic rivers: insights from stable nitrogen isotope studies
Neodymium budget in the Mediterranean Sea: evaluating the role of atmospheric dusts using a high-resolution dynamical-biogeochemical model
Nitrate isotope investigations reveal future impacts of climate change on nitrogen inputs and cycling in Arctic fjords: Kongsfjorden and Rijpfjorden (Svalbard)
Mineralization of autochthonous particulate organic carbon is a fast channel of organic matter turnover in Germany's largest drinking water reservoir
Carbon isotopic ratios of modern C3 and C4 vegetation on the Indian peninsula and changes along the plant–soil–river continuum – implications for vegetation reconstructions
Controls on nitrite oxidation in the upper Southern Ocean: insights from winter kinetics experiments in the Indian sector
Tracing the source of nitrate in a forested stream showing elevated concentrations during storm events
Intra-skeletal variability in phosphate oxygen isotope composition reveals regional heterothermies in marine vertebrates
Isotopic differences in soil–plant–atmosphere continuum composition and control factors of different vegetation zones on the northern slope of the Qilian Mountains
An analysis of the variability in δ13C in macroalgae from the Gulf of California: indicative of carbon concentration mechanisms and isotope discrimination during carbon assimilation
Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf
Particulate biogenic barium tracer of mesopelagic carbon remineralization in the Mediterranean Sea (PEACETIME project)
Hydrogen and carbon isotope fractionation factors of aerobic methane oxidation in deep-sea water
Host-influenced geochemical signature in the parasitic foraminifera Hyrrokkin sarcophaga
Comparing modified substrate-induced respiration with selective inhibition (SIRIN) and N2O isotope approaches to estimate fungal contribution to denitrification in three arable soils under anoxic conditions
How are oxygen budgets influenced by dissolved iron and growth of oxygenic phototrophs in an iron-rich spring system? Initial results from the Espan Spring in Fürth, Germany
Stable isotope ratios in seawater nitrate reflect the influence of Pacific water along the northwest Atlantic margin
High-resolution 14C bomb peak dating and climate response analyses of subseasonal stable isotope signals in wood of the African baobab – a case study from Oman
Geographic variability in freshwater methane hydrogen isotope ratios and its implications for global isotopic source signatures
Seasonality of nitrogen sources, cycling, and loading in a New England river discerned from nitrate isotope ratios
Evaluating the response of δ13C in Haloxylon ammodendron, a dominant C4 species in Asian desert ecosystems, to water and nitrogen addition as well as the availability of its δ13C as an indicator of water use efficiency
Modern silicon dynamics of a small high-latitude subarctic lake
Nitrogen isotopic fractionations during nitric oxide production in an agricultural soil
Silicon uptake and isotope fractionation dynamics by crop species
Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin
Bottomland hardwood forest growth and stress response to hydroclimatic variation: evidence from dendrochronology and tree ring Δ13C values
N2O isotope approaches for source partitioning of N2O production and estimation of N2O reduction – validation with the 15N gas-flux method in laboratory and field studies
Technical note: Single-shell δ11B analysis of Cibicidoides wuellerstorfi using femtosecond laser ablation MC-ICPMS and secondary ion mass spectrometry
Biogeochemical evidence of anaerobic methane oxidation and anaerobic ammonium oxidation in a stratified lake using stable isotopes
Effects of 238U variability and physical transport on water column 234Th downward fluxes in the coastal upwelling system off Peru
Do degree and rate of silicate weathering depend on plant productivity?
Aymeric P. M. Servettaz, Yuta Isaji, Chisato Yoshikawa, Yanghee Jang, Boo-Keun Khim, Yeongjun Ryu, Daniel M. Sigman, Nanako O. Ogawa, Francisco J. Jiménez-Espejo, and Naohiko Ohkouchi
Biogeosciences, 22, 2239–2260, https://doi.org/10.5194/bg-22-2239-2025, https://doi.org/10.5194/bg-22-2239-2025, 2025
Short summary
Short summary
Phytoplankton blooms occur after sea ice retreats in the Southern Ocean. In this study we investigate the influence of seasonal cycle of sea ice concentration on nitrate depletion, testing the hypothesis that meltwater release stabilizes the water column and favors nutrient utilization. We find that, at a regional scale, nitrate depletion and vertical mixing are weakly correlated with sea ice cycle. Nitrate depletion is rather linked to other oceanographic processes controlling mixing depth.
Susann Henkel, Bo Liu, Michael Staubwasser, Simone A. Kasemann, Anette Meixner, David A. Aromokeye, Michael W. Friedrich, and Sabine Kasten
Biogeosciences, 22, 1673–1696, https://doi.org/10.5194/bg-22-1673-2025, https://doi.org/10.5194/bg-22-1673-2025, 2025
Short summary
Short summary
We intend to unravel iron (Fe) reduction pathways in high-deposition methanic sediments because pools of Fe minerals could stimulate methane oxidation and also generation. Our data from the North Sea show that Fe release takes place mechanistically differently to Fe reduction in shallow sediments, which typically fractionates Fe isotopes. We conclude that fermentation of organic matter involving interspecies electron transfer, partly through conductive Fe oxides, could play an important role.
Weitian Ding, Urumu Tsunogai, Tianzheng Huang, Takashi Sambuichi, Wenhua Ruan, Masanori Ito, Hao Xu, Yongwon Kim, and Fumiko Nakagawa
EGUsphere, https://doi.org/10.21203/rs.3.rs-4264720/v2, https://doi.org/10.21203/rs.3.rs-4264720/v2, 2025
Short summary
Short summary
Identifying the pathways of N2O produced through nitrification and denitrification in soil is crucial for effective mitigation. Thus, we monitored a new natural isotopic signature (Δ17O) of N2O in forested soil for identifying the pathways, which is almost stable during various biogeochemical processes. Our results suggest Δ17O is a promising signature for identifying pathways of N2O production, revealing that increased denitrification drives the high emission of N2O in soil on rainy days.
Fawad Khan, Samuel Franco Luesma, Frederik Hartmann, Michael Dannenmann, Rainer Gasche, Clemens Scheer, Andreas Gattinger, Wiebke Niether, Elizabeth Gachibu Wangari, Ricky Mwangada Mwanake, Ralf Kiese, and Benjamin Wolf
EGUsphere, https://doi.org/10.5194/egusphere-2025-292, https://doi.org/10.5194/egusphere-2025-292, 2025
Short summary
Short summary
Crop rotations with legumes and use of organic and mineral fertilizers show potential to reduce agricultural N losses. This study examined N losses, including direct N2 flux, on two adjacent sites with different management history: organic farming (OF) with legume cultivation and integrated farming (IF) using synthetic and organic N inputs. IF increased soil organic carbon and nitrogen content, 15N recovery and showed a balanced N budget, i.e., more efficient N cycling compared to OF.
Ingrid Chanca, Ingeborg Levin, Susan Trumbore, Kita Macario, Jost Lavric, Carlos Alberto Quesada, Alessandro Carioca de Araújo, Cléo Quaresma Dias Júnior, Hella van Asperen, Samuel Hammer, and Carlos A. Sierra
Biogeosciences, 22, 455–472, https://doi.org/10.5194/bg-22-455-2025, https://doi.org/10.5194/bg-22-455-2025, 2025
Short summary
Short summary
Assessing the net carbon (C) budget of the Amazon entails considering the magnitude and timing of C absorption and losses through respiration (transit time of C). Radiocarbon-based estimates of the transit time of C in the Amazon Tall Tower Observatory (ATTO) suggest a change in the transit time from 6 ± 2 years and 18 ± 4 years within 2 years (October 2019 and December 2021, respectively). This variability indicates that only a fraction of newly fixed C can be stored for decades or longer.
Fortunat Joos, Sebastian Lienert, and Sönke Zaehle
Biogeosciences, 22, 19–39, https://doi.org/10.5194/bg-22-19-2025, https://doi.org/10.5194/bg-22-19-2025, 2025
Short summary
Short summary
How plants regulate their exchange of CO2 and water with the atmosphere under global warming is critical for their carbon uptake and their cooling influence. We analyze the isotope ratio of atmospheric CO2 and detect no significant decadal trends in the seasonal cycle amplitude. The data are consistent with the regulation towards leaf CO2 and intrinsic water use efficiency growing proportionally to atmospheric CO2, in contrast to recent suggestions of downregulation of CO2 and water fluxes.
Stanislav Jabinski, Vítězslav Kučera, Marek Kopáček, Jan Jansa, and Travis B. Meador
EGUsphere, https://doi.org/10.5194/egusphere-2024-3153, https://doi.org/10.5194/egusphere-2024-3153, 2024
Short summary
Short summary
Microbial production is a key parameter in estimations of organic matter cycling in environmental systems, and fungi play a major role as decomposers. In order to investigate fungal production and turnover times in soils, we incubated fungal pure cultures with isotopically labelled water and bicarbonate to investigate growth signals encoded into lipid biomarkers, which can be applied to improve flux estimates in environmental studies.
Weitian Ding, Urumu Tsunogai, and Fumiko Nakagawa
Biogeosciences, 21, 4717–4722, https://doi.org/10.5194/bg-21-4717-2024, https://doi.org/10.5194/bg-21-4717-2024, 2024
Short summary
Short summary
Past studies have used the Δ17O of stream nitrate to estimate the gross nitrification rates (GNRs) in each forested catchment by approximating the Δ17O value of soil nitrate to be equal to that of stream nitrate. Based on inference and calculation of measured data, we found that this approximation resulted in an overestimated GNR. Therefore, it is essential to clarify and verify the Δ17O NO3− values in forested soils and streams before applying the Δ17O values of stream NO3− to GNR estimation.
Elise D. Rivett, Wenjuan Ma, Nathaniel E. Ostrom, and Eric L. Hegg
Biogeosciences, 21, 4549–4567, https://doi.org/10.5194/bg-21-4549-2024, https://doi.org/10.5194/bg-21-4549-2024, 2024
Short summary
Short summary
Many different processes produce nitrous oxide (N2O), a potent greenhouse gas. Measuring the ratio of heavy and light nitrogen isotopes (15N/14N) for the non-exchangeable central and outer N atoms of N2O helps to distinguish sources of N2O. To accurately calculate the position-specific isotopic preference, we developed an expansion of the widely used Rayleigh model. Application of our new model to simulated and experimental data demonstrates its improved accuracy for analyzing N2O synthesis.
Eliza Harris, Philipp Fischer, Maciej P. Lewicki, Dominika Lewicka-Szczebak, Stephen J. Harris, and Fernando Perez-Cruz
Biogeosciences, 21, 3641–3663, https://doi.org/10.5194/bg-21-3641-2024, https://doi.org/10.5194/bg-21-3641-2024, 2024
Short summary
Short summary
Greenhouse gases are produced and consumed via a number of pathways. Quantifying these pathways helps reduce the climate and environmental footprint of anthropogenic activities. The contribution of the pathways can be estimated from the isotopic composition, which acts as a fingerprint for these pathways. We have developed the Time-resolved FRactionation And Mixing Evaluation (TimeFRAME) model to simplify interpretation and estimate the contribution of different pathways and their uncertainty.
Kim A. P. Faassen, Jordi Vilà-Guerau de Arellano, Raquel González-Armas, Bert G. Heusinkveld, Ivan Mammarella, Wouter Peters, and Ingrid T. Luijkx
Biogeosciences, 21, 3015–3039, https://doi.org/10.5194/bg-21-3015-2024, https://doi.org/10.5194/bg-21-3015-2024, 2024
Short summary
Short summary
The ratio between atmospheric O2 and CO2 can be used to characterize the carbon balance at the surface. By combining a model and observations from the Hyytiälä forest (Finland), we show that using atmospheric O2 and CO2 measurements from a single height provides a weak constraint on the surface CO2 exchange because large-scale processes such as entrainment confound this signal. We therefore recommend always using multiple heights of O2 and CO2 measurements to study surface CO2 exchange.
Nestor Gaviria-Lugo, Charlotte Läuchli, Hella Wittmann, Anne Bernhardt, Patrick Frings, Mahyar Mohtadi, Oliver Rach, and Dirk Sachse
Biogeosciences, 20, 4433–4453, https://doi.org/10.5194/bg-20-4433-2023, https://doi.org/10.5194/bg-20-4433-2023, 2023
Short summary
Short summary
We analyzed how leaf wax hydrogen isotopes in continental and marine sediments respond to climate along one of the strongest aridity gradients in the world, from hyperarid to humid, along Chile. We found that under extreme aridity, the relationship between hydrogen isotopes in waxes and climate is non-linear, suggesting that we should be careful when reconstructing past hydrological changes using leaf wax hydrogen isotopes so as to avoid overestimating how much the climate has changed.
Ralf Conrad and Peter Claus
Biogeosciences, 20, 3625–3635, https://doi.org/10.5194/bg-20-3625-2023, https://doi.org/10.5194/bg-20-3625-2023, 2023
Short summary
Short summary
Knowledge of carbon isotope fractionation is important for the assessment of the pathways involved in the degradation of organic matter. Propionate is an important intermediate. In the presence of sulfate, it was degraded by Syntrophobacter species via acetate to CO2. In the absence of sulfate, it was mainly consumed by Smithella and methanogenic archaeal species via butyrate and acetate to CH4. However, stable carbon isotope fractionation during the degradation process was quite small.
Alessandro Zanchetta, Linda M. J. Kooijmans, Steven van Heuven, Andrea Scifo, Hubertus A. Scheeren, Ivan Mammarella, Ute Karstens, Jin Ma, Maarten Krol, and Huilin Chen
Biogeosciences, 20, 3539–3553, https://doi.org/10.5194/bg-20-3539-2023, https://doi.org/10.5194/bg-20-3539-2023, 2023
Short summary
Short summary
Carbonyl sulfide (COS) has been suggested as a tool to estimate carbon dioxide (CO2) uptake by plants during photosynthesis. However, understanding its sources and sinks is critical to preventing biases in this estimate. Combining observations and models, this study proves that regional sources occasionally influence the measurements at the 60 m tall Lutjewad tower (1 m a.s.l.; 53°24′ N, 6°21′ E) in the Netherlands. Moreover, it estimates nighttime COS fluxes to be −3.0 ± 2.6 pmol m−2 s−1.
Joel T. Bostic, David M. Nelson, and Keith N. Eshleman
Biogeosciences, 20, 2485–2498, https://doi.org/10.5194/bg-20-2485-2023, https://doi.org/10.5194/bg-20-2485-2023, 2023
Short summary
Short summary
Land-use changes can affect water quality. We used tracers of pollution sources and water flow paths to show that an urban watershed exports variable sources during storm events relative to a less developed watershed. Our results imply that changing precipitation patterns combined with increasing urbanization may alter sources of pollution in the future.
Robin Havas, Christophe Thomazo, Miguel Iniesto, Didier Jézéquel, David Moreira, Rosaluz Tavera, Jeanne Caumartin, Elodie Muller, Purificación López-García, and Karim Benzerara
Biogeosciences, 20, 2405–2424, https://doi.org/10.5194/bg-20-2405-2023, https://doi.org/10.5194/bg-20-2405-2023, 2023
Short summary
Short summary
Dissolved organic carbon (DOC) is a reservoir of prime importance in the C cycle of both continental and marine systems. It has also been suggested to influence the past Earth climate but is still poorly characterized in ancient-Earth-like environments. In this paper we show how DOC analyses from modern redox-stratified lakes can evidence specific metabolic reactions and environmental factors and how these can help us to interpret the C cycle of specific periods in the Earth's past.
Robin Havas, Christophe Thomazo, Miguel Iniesto, Didier Jézéquel, David Moreira, Rosaluz Tavera, Jeanne Caumartin, Elodie Muller, Purificación López-García, and Karim Benzerara
Biogeosciences, 20, 2347–2367, https://doi.org/10.5194/bg-20-2347-2023, https://doi.org/10.5194/bg-20-2347-2023, 2023
Short summary
Short summary
We describe the C cycle of four modern stratified water bodies from Mexico, a necessary step to better understand the C cycle of primitive-Earth-like environments, which were dominated by these kinds of conditions. We highlight the importance of local external factors on the C cycle of these systems. Notably, they influence the sensitivity of the carbonate record to environmental changes. We also show the strong C-cycle variability among these lakes and their organic C sediment record.
Yifan Ma, Kuanbo Zhou, Weifang Chen, Junhui Chen, Jin-Yu Terence Yang, and Minhan Dai
Biogeosciences, 20, 2013–2030, https://doi.org/10.5194/bg-20-2013-2023, https://doi.org/10.5194/bg-20-2013-2023, 2023
Short summary
Short summary
We distinguished particulate organic carbon (POC) export fluxes out of the nutrient-depleted layer (NDL) and the euphotic zone. The amount of POC export flux at the NDL base suggests that the NDL could be a hotspot of particle export. The substantial POC export flux at the NDL base challenges traditional concepts that the NDL was limited in terms of POC export. The dominant nutrient source for POC export fluxes should be subsurface nutrients, which was determined by 15N isotopic mass balance.
Clémence Paul, Clément Piel, Joana Sauze, Nicolas Pasquier, Frédéric Prié, Sébastien Devidal, Roxanne Jacob, Arnaud Dapoigny, Olivier Jossoud, Alexandru Milcu, and Amaëlle Landais
Biogeosciences, 20, 1047–1062, https://doi.org/10.5194/bg-20-1047-2023, https://doi.org/10.5194/bg-20-1047-2023, 2023
Short summary
Short summary
To improve the interpretation of the δ18Oatm and Δ17O of O2 in air bubbles in ice cores, we need to better quantify the oxygen fractionation coefficients associated with biological processes. We performed a simplified analogue of the terrestrial biosphere in a closed chamber. We found a respiration fractionation in agreement with the previous estimates at the microorganism scale, and a terrestrial photosynthetic fractionation was found. This has an impact on the estimation of the Dole effect.
Adam Francis, Raja S. Ganeshram, Robyn E. Tuerena, Robert G. M. Spencer, Robert M. Holmes, Jennifer A. Rogers, and Claire Mahaffey
Biogeosciences, 20, 365–382, https://doi.org/10.5194/bg-20-365-2023, https://doi.org/10.5194/bg-20-365-2023, 2023
Short summary
Short summary
Climate change is causing extensive permafrost degradation and nutrient releases into rivers with great ecological impacts on the Arctic Ocean. We focused on nitrogen (N) release from this degradation and associated cycling using N isotopes, an understudied area. Many N species are released at degradation sites with exchanges between species. N inputs from permafrost degradation and seasonal river N trends were identified using isotopes, helping to predict climate change impacts.
Mohamed Ayache, Jean-Claude Dutay, Kazuyo Tachikawa, Thomas Arsouze, and Catherine Jeandel
Biogeosciences, 20, 205–227, https://doi.org/10.5194/bg-20-205-2023, https://doi.org/10.5194/bg-20-205-2023, 2023
Short summary
Short summary
The neodymium (Nd) is one of the most useful tracers to fingerprint water mass provenance. However, the use of Nd is hampered by the lack of adequate quantification of the external sources. Here, we present the first simulation of dissolved Nd concentration and Nd isotopic composition in the Mediterranean Sea using a high-resolution model. We aim to better understand how the various external sources affect the Nd cycle and particularly assess how it is impacted by atmospheric inputs.
Marta Santos-Garcia, Raja S. Ganeshram, Robyn E. Tuerena, Margot C. F. Debyser, Katrine Husum, Philipp Assmy, and Haakon Hop
Biogeosciences, 19, 5973–6002, https://doi.org/10.5194/bg-19-5973-2022, https://doi.org/10.5194/bg-19-5973-2022, 2022
Short summary
Short summary
Terrestrial sources of nitrate are important contributors to the nutrient pool in the fjords of Kongsfjorden and Rijpfjorden in Svalbard during the summer, and they sustain most of the fjord primary productivity. Ongoing tidewater glacier retreat is postulated to favour light limitation and less dynamic circulation in fjords. This is suggested to encourage the export of nutrients to the middle and outer part of the fjord system, which may enhance primary production within and in offshore areas.
Marlene Dordoni, Michael Seewald, Karsten Rinke, Kurt Friese, Robert van Geldern, Jakob Schmidmeier, and Johannes A. C. Barth
Biogeosciences, 19, 5343–5355, https://doi.org/10.5194/bg-19-5343-2022, https://doi.org/10.5194/bg-19-5343-2022, 2022
Short summary
Short summary
Organic matter (OM) turnover into dissolved inorganic carbon (DIC) was investigated by means of carbon isotope mass balances in Germany's largest water reservoir. This includes a metalimnetic oxygen minimum (MOM). Autochthonous particulate organic carbon (POC) was the main contributor to DIC, with rates that were highest for the MOM. Generally low turnover rates outline the environmental fragility of this water body in the case that OM loads increase due to storm events or land use changes.
Frédérique M. S. A. Kirkels, Hugo J. de Boer, Paulina Concha Hernández, Chris R. T. Martes, Marcel T. J. van der Meer, Sayak Basu, Muhammed O. Usman, and Francien Peterse
Biogeosciences, 19, 4107–4127, https://doi.org/10.5194/bg-19-4107-2022, https://doi.org/10.5194/bg-19-4107-2022, 2022
Short summary
Short summary
The distinct carbon isotopic values of C3 and C4 plants are widely used to reconstruct past hydroclimate, where more C3 plants reflect wetter and C4 plants drier conditions. Here we examine the impact of regional hydroclimatic conditions on plant isotopic values in the Godavari River basin, India. We find that it is crucial to identify regional plant isotopic values and consider drought stress, which introduces a bias in C3 / C4 plant estimates and associated hydroclimate reconstructions.
Mhlangabezi Mdutyana, Tanya Marshall, Xin Sun, Jessica M. Burger, Sandy J. Thomalla, Bess B. Ward, and Sarah E. Fawcett
Biogeosciences, 19, 3425–3444, https://doi.org/10.5194/bg-19-3425-2022, https://doi.org/10.5194/bg-19-3425-2022, 2022
Short summary
Short summary
Nitrite-oxidizing bacteria in the winter Southern Ocean show a high affinity for nitrite but require a minimum (i.e., "threshold") concentration before they increase their rates of nitrite oxidation significantly. The classic Michaelis–Menten model thus cannot be used to derive the kinetic parameters, so a modified equation was employed that also yields the threshold nitrite concentration. Dissolved iron availability may play an important role in limiting nitrite oxidation.
Weitian Ding, Urumu Tsunogai, Fumiko Nakagawa, Takashi Sambuichi, Hiroyuki Sase, Masayuki Morohashi, and Hiroki Yotsuyanagi
Biogeosciences, 19, 3247–3261, https://doi.org/10.5194/bg-19-3247-2022, https://doi.org/10.5194/bg-19-3247-2022, 2022
Short summary
Short summary
Excessive leaching of nitrate from forested catchments during storm events degrades water quality and causes eutrophication in downstream areas. Thus, tracing the source of nitrate increase during storm events in forested streams is important for sustainable forest management. Based on the isotopic compositions of stream nitrate, including Δ17O, this study clarifies that the source of stream nitrate increase during storm events was soil nitrate in the riparian zone.
Nicolas Séon, Romain Amiot, Guillaume Suan, Christophe Lécuyer, François Fourel, Fabien Demaret, Arnauld Vinçon-Laugier, Sylvain Charbonnier, and Peggy Vincent
Biogeosciences, 19, 2671–2681, https://doi.org/10.5194/bg-19-2671-2022, https://doi.org/10.5194/bg-19-2671-2022, 2022
Short summary
Short summary
We analysed the oxygen isotope composition of bones and teeth of four marine species possessing regional heterothermies. We observed a consistent link between oxygen isotope composition and temperature heterogeneities recorded by classical methods. This opens up new perspectives on the determination of the thermoregulatory strategies of extant marine vertebrates where conventional methods are difficult to apply, but also allows us to investigate thermophysiologies of extinct vertebrates.
Yuwei Liu, Guofeng Zhu, Zhuanxia Zhang, Zhigang Sun, Leilei Yong, Liyuan Sang, Lei Wang, and Kailiang Zhao
Biogeosciences, 19, 877–889, https://doi.org/10.5194/bg-19-877-2022, https://doi.org/10.5194/bg-19-877-2022, 2022
Short summary
Short summary
We took the water cycle process of soil–plant–atmospheric precipitation as the research objective. In the water cycle of soil–plant–atmospheric precipitation, precipitation plays the main controlling role. The main source of replenishment for alpine meadow plants is precipitation and alpine meltwater; the main source of replenishment for forest plants is soil water; and the plants in the arid foothills mainly use groundwater.
Roberto Velázquez-Ochoa, María Julia Ochoa-Izaguirre, and Martín Federico Soto-Jiménez
Biogeosciences, 19, 1–27, https://doi.org/10.5194/bg-19-1-2022, https://doi.org/10.5194/bg-19-1-2022, 2022
Short summary
Short summary
Our research is the first approximation to understand the δ13C macroalgal variability in one of the most diverse marine ecosystems in the world, the Gulf of California. The life-form is the principal cause of δ13C macroalgal variability, mainly taxonomy. However, changes in habitat characteristics and environmental conditions also influence the δ13C macroalgal variability. The δ13C macroalgae is indicative of carbon concentration mechanisms and isotope discrimination during carbon assimilation.
Raquel F. Flynn, Thomas G. Bornman, Jessica M. Burger, Shantelle Smith, Kurt A. M. Spence, and Sarah E. Fawcett
Biogeosciences, 18, 6031–6059, https://doi.org/10.5194/bg-18-6031-2021, https://doi.org/10.5194/bg-18-6031-2021, 2021
Short summary
Short summary
Biological activity in the shallow Weddell Sea affects the biogeochemistry of recently formed deep waters. To investigate the drivers of carbon and nutrient export, we measured rates of primary production and nitrogen uptake, characterized the phytoplankton community, and estimated nutrient depletion ratios across the under-sampled western Weddell Sea in mid-summer. Carbon export was highest at the ice shelves and was determined by a combination of physical, chemical, and biological factors.
Stéphanie H. M. Jacquet, Christian Tamburini, Marc Garel, Aurélie Dufour, France Van Vambeke, Frédéric A. C. Le Moigne, Nagib Bhairy, and Sophie Guasco
Biogeosciences, 18, 5891–5902, https://doi.org/10.5194/bg-18-5891-2021, https://doi.org/10.5194/bg-18-5891-2021, 2021
Short summary
Short summary
We compared carbon remineralization rates (MRs) in the western and central Mediterranean Sea in late spring during the PEACETIME cruise, as assessed using the barium tracer. We reported higher and deeper (up to 1000 m depth) MRs in the western basin, potentially sustained by an additional particle export event driven by deep convection. The central basin is the site of a mosaic of blooming and non-blooming water masses and showed lower MRs that were restricted to the upper mesopelagic layer.
Shinsuke Kawagucci, Yohei Matsui, Akiko Makabe, Tatsuhiro Fukuba, Yuji Onishi, Takuro Nunoura, and Taichi Yokokawa
Biogeosciences, 18, 5351–5362, https://doi.org/10.5194/bg-18-5351-2021, https://doi.org/10.5194/bg-18-5351-2021, 2021
Short summary
Short summary
Hydrogen and carbon isotope ratios of methane as well as the relevant biogeochemical parameters and microbial community compositions in hydrothermal plumes in the Okinawa Trough were observed. We succeeded in simultaneously determining hydrogen and carbon isotope fractionation factors associated with aerobic oxidation of methane in seawater (εH = 49.4 ± 5.0 ‰, εC = 5.2 ± 0.4 ‰) – the former being the first of its kind ever reported.
Nicolai Schleinkofer, David Evans, Max Wisshak, Janina Vanessa Büscher, Jens Fiebig, André Freiwald, Sven Härter, Horst R. Marschall, Silke Voigt, and Jacek Raddatz
Biogeosciences, 18, 4733–4753, https://doi.org/10.5194/bg-18-4733-2021, https://doi.org/10.5194/bg-18-4733-2021, 2021
Short summary
Short summary
We have measured the chemical composition of the carbonate shells of the parasitic foraminifera Hyrrokkin sarcophaga in order to test if it is influenced by the host organism (bivalve or coral). We find that both the chemical and isotopic composition is influenced by the host organism. For example strontium is enriched in foraminifera that grew on corals, whose skeleton is built from aragonite, which is naturally enriched in strontium compared to the bivalves' calcite shell.
Lena Rohe, Traute-Heidi Anderson, Heinz Flessa, Anette Goeske, Dominika Lewicka-Szczebak, Nicole Wrage-Mönnig, and Reinhard Well
Biogeosciences, 18, 4629–4650, https://doi.org/10.5194/bg-18-4629-2021, https://doi.org/10.5194/bg-18-4629-2021, 2021
Short summary
Short summary
This is the first experimental setup combining a complex set of methods (microbial inhibitors and isotopic approaches) to differentiate between N2O produced by fungi or bacteria during denitrification in three soils. Quantifying the fungal fraction with inhibitors was not successful due to large amounts of uninhibited N2O production. All successful methods suggested a small or missing fungal contribution. Artefacts occurring with microbial inhibition to determine N2O fluxes are discussed.
Inga Köhler, Raul E. Martinez, David Piatka, Achim J. Herrmann, Arianna Gallo, Michelle M. Gehringer, and Johannes A. C. Barth
Biogeosciences, 18, 4535–4548, https://doi.org/10.5194/bg-18-4535-2021, https://doi.org/10.5194/bg-18-4535-2021, 2021
Short summary
Short summary
We investigated how high Fe(II) levels influence the O2 budget of a circum-neutral Fe(II)-rich spring and if a combined study of dissolved O (DO) and its isotopic composition can help assess this effect. We showed that dissolved Fe(II) can exert strong effects on the δ18ODO even though a constant supply of atmospheric O2 occurs. In the presence of photosynthesis, direct effects of Fe oxidation become masked. Critical Fe(II) concentrations indirectly control the DO by enhancing photosynthesis.
Owen A. Sherwood, Samuel H. Davin, Nadine Lehmann, Carolyn Buchwald, Evan N. Edinger, Moritz F. Lehmann, and Markus Kienast
Biogeosciences, 18, 4491–4510, https://doi.org/10.5194/bg-18-4491-2021, https://doi.org/10.5194/bg-18-4491-2021, 2021
Short summary
Short summary
Pacific water flowing eastward through the Canadian Arctic plays an important role in redistributing nutrients to the northwest Atlantic Ocean. Using samples collected from northern Baffin Bay to the southern Labrador Shelf, we show that stable isotopic ratios in seawater nitrate reflect the fraction of Pacific to Atlantic water. These results provide a new framework for interpreting patterns of nitrogen isotopic variability recorded in modern and archival organic materials in the region.
Franziska Slotta, Lukas Wacker, Frank Riedel, Karl-Uwe Heußner, Kai Hartmann, and Gerhard Helle
Biogeosciences, 18, 3539–3564, https://doi.org/10.5194/bg-18-3539-2021, https://doi.org/10.5194/bg-18-3539-2021, 2021
Short summary
Short summary
The African baobab is a challenging climate and environmental archive for its semi-arid habitat due to dating uncertainties and parenchyma-rich wood anatomy. Annually resolved F14C data of tree-ring cellulose (1941–2005) from a tree in Oman show the annual character of the baobab’s growth rings but were up to 8.8 % lower than expected for 1964–1967. Subseasonal δ13C and δ18O patterns reveal years with low average monsoon rain as well as heavy rainfall events from pre-monsoonal cyclones.
Peter M. J. Douglas, Emerald Stratigopoulos, Sanga Park, and Dawson Phan
Biogeosciences, 18, 3505–3527, https://doi.org/10.5194/bg-18-3505-2021, https://doi.org/10.5194/bg-18-3505-2021, 2021
Short summary
Short summary
Hydrogen isotopes could be a useful tool to help resolve the geographic distribution of methane emissions from freshwater environments. We analyzed an expanded global dataset of freshwater methane hydrogen isotope ratios and found significant geographic variation linked to water isotopic composition. This geographic variability could be used to resolve changing methane fluxes from freshwater environments and provide more accurate estimates of the relative balance of global methane sources.
Veronica R. Rollinson, Julie Granger, Sydney C. Clark, Mackenzie L. Blanusa, Claudia P. Koerting, Jamie M. P. Vaudrey, Lija A. Treibergs, Holly C. Westbrook, Catherine M. Matassa, Meredith G. Hastings, and Craig R. Tobias
Biogeosciences, 18, 3421–3444, https://doi.org/10.5194/bg-18-3421-2021, https://doi.org/10.5194/bg-18-3421-2021, 2021
Short summary
Short summary
We measured nutrients and the naturally occurring nitrogen (N) and oxygen (O) stable isotope ratios of nitrate discharged from a New England river over an annual cycle, to monitor N loading and identify dominant sources from the watershed. We uncovered a seasonality to loading and sources of N from the watershed. Seasonality in the nitrate isotope ratios also informed on N cycling, conforming to theoretical expectations of riverine nutrient cycling.
Zixun Chen, Xuejun Liu, Xiaoqing Cui, Yaowen Han, Guoan Wang, and Jiazhu Li
Biogeosciences, 18, 2859–2870, https://doi.org/10.5194/bg-18-2859-2021, https://doi.org/10.5194/bg-18-2859-2021, 2021
Short summary
Short summary
δ13C in plants is a sensitive long-term indicator of physiological acclimatization. The present study suggests that precipitation change and increasing atmospheric N deposition have little impact on δ13C of H. ammodendron, a dominant plant in central Asian deserts, but affect its gas exchange. In addition, this study shows that δ13C of H. ammodendron could not indicate its water use efficiency (WUE), suggesting that whether δ13C of C4 plants indicates WUE is species-specific.
Petra Zahajská, Carolina Olid, Johanna Stadmark, Sherilyn C. Fritz, Sophie Opfergelt, and Daniel J. Conley
Biogeosciences, 18, 2325–2345, https://doi.org/10.5194/bg-18-2325-2021, https://doi.org/10.5194/bg-18-2325-2021, 2021
Short summary
Short summary
The drivers of high accumulation of single-cell siliceous algae (diatoms) in a high-latitude lake have not been fully characterized before. We studied silicon cycling of the lake through water, radon, silicon, and stable silicon isotope balances. Results showed that groundwater brings 3 times more water and dissolved silica than the stream inlet. We demonstrate that groundwater discharge and low sediment deposition have driven the high diatom accumulation in the studied lake in the past century.
Zhongjie Yu and Emily M. Elliott
Biogeosciences, 18, 805–829, https://doi.org/10.5194/bg-18-805-2021, https://doi.org/10.5194/bg-18-805-2021, 2021
Short summary
Short summary
In this study, we demonstrated distinct nitrogen isotope effects for nitric oxide (NO) production from major microbial and chemical NO sources in an agricultural soil. These results highlight characteristic bond-forming and breaking mechanisms associated with microbial and chemical NO production and implicate that simultaneous isotopic analyses of NO and nitrous oxide (N2O) can lead to unprecedented insights into the sources and processes controlling NO and N2O emissions from agricultural soils.
Daniel A. Frick, Rainer Remus, Michael Sommer, Jürgen Augustin, Danuta Kaczorek, and Friedhelm von Blanckenburg
Biogeosciences, 17, 6475–6490, https://doi.org/10.5194/bg-17-6475-2020, https://doi.org/10.5194/bg-17-6475-2020, 2020
Short summary
Short summary
Silicon is taken up by some plants to increase structural stability and to develop stress resistance and is rejected by others. To explore the underlying mechanisms, we used the stable isotopes of silicon that shift in their relative abundance depending on the biochemical transformation involved. On species with a rejective (tomato, mustard) and active (wheat) uptake mechanism, grown in hydroculture, we found that the transport of silicic acid is controlled by the precipitation of biogenic opal.
Quentin Charbonnier, Julien Bouchez, Jérôme Gaillardet, and Éric Gayer
Biogeosciences, 17, 5989–6015, https://doi.org/10.5194/bg-17-5989-2020, https://doi.org/10.5194/bg-17-5989-2020, 2020
Short summary
Short summary
The abundance and isotope composition of the trace metal barium (Ba) allows us to track and quantify nutrient cycling throughout the Amazon Basin. In particular, we show that the Ba biological fingerprint evolves from that of a strong net nutrient uptake in the mountainous area of the Andes towards efficient nutrient recycling on the plains of the Lower Amazon. Our study highlights the fact that the geochemical signature of rock-derived nutrients transported by the Amazon is scarred by life.
Ajinkya G. Deshpande, Thomas W. Boutton, Ayumi Hyodo, Charles W. Lafon, and Georgianne W. Moore
Biogeosciences, 17, 5639–5653, https://doi.org/10.5194/bg-17-5639-2020, https://doi.org/10.5194/bg-17-5639-2020, 2020
Short summary
Short summary
Wetland forests in the southern USA are threatened by changing climate and human-induced pressures. We used tree ring widths and C isotopes as indicators of forest growth and physiological stress, respectively, and compared these to past climate data. We observed that vegetation growing in the drier patches is susceptible to stress, while vegetation growth and physiology in wetter patches is less sensitive to unfavorable environmental conditions, highlighting the importance of optimal wetness.
Dominika Lewicka-Szczebak, Maciej Piotr Lewicki, and Reinhard Well
Biogeosciences, 17, 5513–5537, https://doi.org/10.5194/bg-17-5513-2020, https://doi.org/10.5194/bg-17-5513-2020, 2020
Short summary
Short summary
We present the first validation of N2O isotopic approaches for estimating N2O source pathways and N2O reduction. These approaches are widely used for tracing soil nitrogen cycling, but the results of these estimations are very uncertain. Here we report the results from parallel treatments allowing for precise validation of these approaches, and we propose the best strategies for results interpretation, including the new idea of an isotope model integrating three isotopic signatures of N2O.
Markus Raitzsch, Claire Rollion-Bard, Ingo Horn, Grit Steinhoefel, Albert Benthien, Klaus-Uwe Richter, Matthieu Buisson, Pascale Louvat, and Jelle Bijma
Biogeosciences, 17, 5365–5375, https://doi.org/10.5194/bg-17-5365-2020, https://doi.org/10.5194/bg-17-5365-2020, 2020
Short summary
Short summary
The isotopic composition of boron in carbonate shells of marine unicellular organisms is a popular tool to estimate seawater pH. Usually, many shells need to be dissolved and measured for boron isotopes, but the information on their spatial distribution is lost. Here, we investigate two techniques that allow for measuring boron isotopes within single shells and show that they yield robust mean values but provide additional information on the heterogeneity within and between single shells.
Florian Einsiedl, Anja Wunderlich, Mathieu Sebilo, Ömer K. Coskun, William D. Orsi, and Bernhard Mayer
Biogeosciences, 17, 5149–5161, https://doi.org/10.5194/bg-17-5149-2020, https://doi.org/10.5194/bg-17-5149-2020, 2020
Short summary
Short summary
Nitrate pollution of freshwaters and methane emissions into the atmosphere are crucial factors in deteriorating the quality of drinking water and in contributing to global climate change. Here, we report vertical concentration and stable isotope profiles of CH4, NO3-, NO2-, and NH4+ in the water column of Fohnsee (southern Bavaria, Germany) that may indicate linkages between nitrate-dependent anaerobic methane oxidation and the anaerobic oxidation of ammonium.
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
Short summary
Short summary
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.
Ralf A. Oeser and Friedhelm von Blanckenburg
Biogeosciences, 17, 4883–4917, https://doi.org/10.5194/bg-17-4883-2020, https://doi.org/10.5194/bg-17-4883-2020, 2020
Short summary
Short summary
We present a novel strategy to decipher the relative impact of biogenic and abiotic drivers of weathering. We parameterized the nutrient fluxes in four ecosystems along a climate and vegetation gradient situated on the Chilean Coastal Cordillera. We investigated how nutrient demand by plants drives weathering. We found that the increase in biomass nutrient demand is accommodated by faster nutrient recycling rather than an increase in the weathering–release rates.
Cited articles
Achterberg, E. P., Steigenberger, S., Marsay, C. M., LeMoigne, F. A. C., Painter, S. C., Baker, A. R., Connelly, D. P., Moore, C. M., Tagliabue, A., and Tanhua, T.: Iron biogeochemistry in the high
latitude North Atlantic Ocean, Sci. Rep., 8, 1283, https://doi.org/10.1038/s41598-018-19472-1, 2018.
Achterberg, E. P., Steigenberger, S., Klar, J. K., Browning, T. J., Marsay,
C. M., Painter, S. C., Vieira, L., Baker, A. R., Hamilton, D. S., Tanhua, T.,
and Moore, C. M.: Trace element biogeochemistry in the high latitude North
Atlantic Ocean; seasonal variations and volcanic inputs, Global
Biogeochem. Cy., e2020GB006674, https://doi.org/10.1029/2020GB006674, online first,
2020.
Beal, L. M., De Ruijter, W. P. M., Biastoch, A., Zahn, R., and the SCOR/WCRP/IAPSO Working Group 136:
On the role of the Agulhas system in ocean circulation and climate, Nature,
472, 429–436, https://doi.org/10.1038/nature09983, 2011.
Blain, S., Quéguiner, B., Armand, L., Belviso, S., Bombled, B., Bopp, L., Bowie, A., Brunet, C., Brussaard, C., Carlotti, F., Christaki, U., Corbière, A., Durand, I., Ebersbach, F., Fuda, J.-L., Garcia, N., Gerringa, L., Griffiths, B., Guigue, C., Guillerm, C., Jacquet, S., Jeandel, C., Laan, P., Lefèvre, D., Monaco, C. L., Malits, A., Mosseri, J., Obernosterer, I., Park, Y.-H., Picheral, M., Pondaven, P., Remenyi, T., Sandroni, V., Sarthou, G., Savoye, N., Scouarnec, L., Souhaut, M., Thuiller, D., Timmermans, K., Trull, T., Uitz, J., van Beek, P., Veldhuis, M., Vincent, D., Viollier, E., Vong, L., and Wagener T.: Effect of natural iron
fertilization on carbon sequestration in the Southern Ocean, Nature, 446,
1070–1074, https://doi.org/10.1038/nature05700, 2007.
Bown, J., Boye, M., Baker, A., Duvieilbourg, E., Lacan, F., Le Moigne, F.,
Planchon, F., Speich, S., and Nelson, D. M.: The biogeochemical cycle of
dissolved cobalt in the Atlantic and the Southern Ocean south off the coast
of South Africa, Mar. Chem., 126, 193–206, https://doi.org/10.1016/j.marchem.2011.03.008, 2011.
Broecker, W. S., Goddard, J., and Sarmiento, J. L.: Distribution of Ra-226 in
Atlantic Ocean, Earth Planet. Sci. Lett., 32, 220–235, https://doi.org/10.1016/0012-821X(76)90063-7, 1976.
Browning, T. J., Bouman, H. A., Moore, C. M., Schlosser, C., Tarran, G. A., Woodward, E. M. S., and Henderson, G. M.: Nutrient regimes control phytoplankton ecophysiology in the South Atlantic, Biogeosciences, 11, 463–479, https://doi.org/10.5194/bg-11-463-2014, 2014.
Browning, T. J., Achterberg, E. P., Yong, J. C., Rapp, I., Utermann, C., and
Moore, C. M.: Iron limitation of microbial phosphorus acquisition in the
tropical North Atlantic, Nat. Commun., 8, 15465, https://doi.org/10.1038/ncomms15465, 2017.
Bruland, K. W. and Franks, R. P.: Mn, Ni, Cu, Zn and Cd in the Western North
Atlantic, in: Trace Metals in Sea Water, edited by: Wong, C. S., Boyle, E.,
Bruland, K. W., Burton, J. D., and Goldberg, E. D., Springer, Boston, MA, USA, 395–414, https://doi.org/10.1007/978-1-4757-6864-0_23, 1983.
Cai, P., Huang, Y., Chen, M., Guo, L., Liu, G., and, Qiu, Y.: New production
based on Ra-228-derived nutrient budgets and thorium-estimated POC export at
the intercalibration station in the South China Sea, Deep-Sea Res., 49, 53–66, https://doi.org/10.1016/S0967-0637(01)00040-1, 2002.
Carr, A. S. and Botha, G. A.: Coastal Geomorphology, in: Southern African
Geomorphology: Recent Trends and New Directions, edited by: Holmes, P. and
Meadows, M. E., Sun Press, Bloemfontein, South Africa, 269–303, 2012.
Chance, R., Jickells, T. D., and Baker, A. R.: Atmospheric trace metal
concentrations, solubility and deposition fluxes in remote marine air over
the south-east Atlantic, Mar. Chem., 177, 45–56, https://doi.org/10.1016/j.marchem.2015.06.028, 2015.
Charette, M. A., Gonneea, M. E., Morris, P. J., Statham, P., Fones, G.,
Planquette, H., Salter, I., and Garabato, A. N.: Radium isotopes as tracers
of iron sources fueling a Southern Ocean phytoplankton bloom, Deep-Sea
Res., 54, 1989–1998, https://doi.org/10.1016/j.dsr2.2007.06.003, 2007.
Charette, M. A., Morris, P. J., Henderson, P. B., and Moore, W. S.: Radium
isotope distributions during the US GEOTRACES North Atlantic cruises, Mar.
Chem., 177, 184–195, https://doi.org/10.1016/j.marchem.2015.01.001, 2015.
Charette, M. A., Lam, P. J., Lohan, M. C., Kwon, E. Y., Hatje, V., Jeandel, C.,
Shiller, A. M., Cutter, G. A., Thomas, A., Boyd, P. W., Homoky, W. B.,
Milne, A., Thomas, H., Andersson, P. S., Porcelli, D., Tanaka, T.,
Geibert, W., Dehairs, F., and Garcia-Orellana, J.: Coastal ocean and
shelf-sea biogeochemical cycling of trace elements and isotopes: lessons
learned from GEOTRACES, Philos. T. R. Soc. A, 374, 20160076, https://doi.org/10.1098/rsta.2016.0076, 2016.
Chever, F., Bucciarelli, E., Sarthou, G., Speich, S., Arhan, M., Penven, P.,
and Tagliabue, A.: Physical speciation of iron in the Atlantic sector of the
Southern Ocean along a transect from the subtropical domain to the Weddell
Sea Gyre, J. Geophys. Res.-Oceans, 115, C10059, https://doi.org/10.1029/2009JC005880, 2010.
Clough, R., Floor, G. H., Quétel, C. R., Milne, A., Lohan, M. C., and Worsfold,
P. J.: Measurement uncertainty associated with shipboard sample collection
and filtration for the determination of the concentration of iron in
seawater, Anal. Methods, 8, 6711–6719, https://doi.org/10.1039/C6AY01551D, 2016.
Cochran, J. K.: The oceanic chemistry of the uranium- and thorium-series
nuclides, in: Uranium-Series Disequilibrium: Applications to Earth, Marine,
and Environmental Sciences, edited by: Ivanovich, M. and Harmon R. S.,
Clarendon Press, Oxford, UK, 334–391, 1992.
Cutter, G, Andersson, P., Codispoti, L, Croot, P., Francois, R., Lohan,
M. C., Obata, H., and Rutgers van der Loeff, M.: Sampling and sample-handling
protocols for GEOTRACES cruises, available at:
http://www.geotraces.org/libraries/documents/Intercalibration/Cookbook.pdf (last access: 10 January 2021), 2010.
Dulaiova, H., Ardelan, M. V., Henderson, P. B.,
and Charette, M. A.: Shelf-derived iron inputs drive biological productivity
in the southern Drake Passage, Global Biogeochem. Cy., 23, GB4014,
https://doi.org/10.1029/2008GB003406, 2009.
Emery, K. O.: Atlantic continental shelf and slope of the United States: U.S.
Geological Survey Professional Papers, 529, 1–23, 1966.
Foster, D. A., Staubwasser, M., and Henderson, G. M.: Ra-226 and Ba
concentrations in the Ross Sea measured with multicollector ICP mass
spectrometry, Mar. Chem., 87, 59–71, https://doi.org/10.1016/j.marchem.2004.02.003, 2004.
Gaiero, D. M., Simonella, L., Gassó, S., Gili, S., Stein, A. F., Sosa, P.,
Becchio, R., Arce, J., and Marelli, H.: Ground/satellite observations and
atmospheric modeling of dust storms originating in the high Puna- Altiplano
deserts (South America), implications for the interpretation of
paleo-climatic archives, J. Geophys. Res.-Atmos., 118,
3817–3831, https://doi.org/10.1002/jgrd.50036, 2013.
Geibert, W., Rodellas, V., Annett, A., van Beek, P., Garcia-Orellana, J.,
Hsieh, Y.-T., and Masque, P.: 226Ra determination via the rate of 222Rn ingrowth
with the Radium Delayed Coincidence Counter (RaDeCC), Limnol.
Oceanogr.-Meth., 11, 594–603, https://doi.org/10.4319/lom.2013.11.594, 2013.
Graham, R. M., De Boer, A. M., van Sebille, E., Kohfeld, K. E., and Schlosser,
C.: Inferring source regions and supply mechanisms of iron in the Southern
Ocean from satellite chlorophyll data, Deep Sea Res., 104, 9–25,
https://doi.org/10.1016/j.dsr.2015.05.007, 2015.
Hanfland, C.: Radium-226 and Radium-228 in the Atlantic sector of the
Southern Ocean, PhD thesis, Alfred Wegener Institut fur Polar und
Meeresforschung, Bremerhaven, Germany, 135 pp., 2002.
Hawco, N. J., Ohnemus, D. C., Resing, J. A., Twining, B. S., and Saito, M. A.: A dissolved cobalt plume in the oxygen minimum zone of the eastern tropical South Pacific, Biogeosciences, 13, 5697–5717, https://doi.org/10.5194/bg-13-5697-2016, 2016.
Hayes, C. T., Black, E. E., Anderson, R. F., Baskaran, M., Buesseler, K. O.,
Charette, M. A., Cheng, H., Cochran, J. K., Edwards, R. L., Fitzgerald, P.,
Lam, P. J., Lu, Y., Morris, S. O., Ohnemus, D. C., Pavia, F. J., Stewart, G.,
and Tang, Y.: Flux of Particulate Elements in the North Atlantic Ocean
Constrained by Multiple Radionuclides, Global Biogeochem. Cy., 32,
1738–1758, 2018.
Homoky, W., John, S. G., Conway, T. M., and Mills, R. A.: Distinct iron
isotopic signatures and supply from marine sediment dissolution, Nat.
Commun., 4, 2143, https://doi.org/10.1038/ncomms3143, 2013.
Hooker, Y., Prieto-Rios, E., and Solís-Marín, F. A.: Echinoderms of
Peru, in: Echinoderm research and diversity in Latin America, edited by:
Alvarado-Barrientos, J. J. and Solís-Marín, F. A., Springer,
Berlin, Germany, 277–299, 2013.
Hsieh, Y.-T. and Henderson, G. M.: Precise measurement of
Jenkins, W. J.: Nitrate Flux into the Euphotic Zone near Bermuda, Nature,
331, 521–523, https://doi.org/10.1038/331521a0, 1988.
Kadko, D., Aguilar-Islas, A., Buck, C. S., Fitzsimmons, J. N., Landing, W. M.,
Shiller, A., Till, C. P., Bruland, K. W., Boyle, E. A., and Anderson, R. F.:
Sources, fluxes and residence times of trace elements measured during the
U.S. GEOTRACES East Pacific Zonal Transect, Mar. Chem., 222, 103781,
https://doi.org/10.1016/j.marchem.2020.103781, 2020.
Kaufman, A., Trier, R., Broecker, W. S., and Feely, H. W.: Distribution of
228Ra in the world ocean, J. Geophys. Res., 78, 8827–8848,
https://doi.org/10.1029/JC078i036p08827, 1973.
Key, R. M., Rotter, R. J., McDonald, G. J., and Slater, R. D.: Western Boundary
Exchange Experiment Final Data Report for large volume samples 228Ra, 226Ra,
9Be, and 10Be Results, Technical Report 90-1, Ocean Tracer Laboratory, Department of
Geology and Geophysics, Princeton University, Princeton, USA, 298 pp., 1990.
Key, R. M., Moore, W. S., and Sarmiento, J. L.: Transient Tracers in the Ocean
North Atlantic Study Final Data Report for 228Ra and 226Ra, Technical Report
92-2, Ocean Tracer Laboratory, Department of Geology and Geophysics, Princeton
University, Princeton, USA, 193 pp., 1992a.
Key, R. M., Moore, W. S., and Sarmiento, J. L.: Transient Tracers in the Ocean
Tropical Atlantic Study Final Data Report for 228Ra and 226Ra, Technical
Report 92-3, Ocean Tracer Laboratory, Department of Geology and Geophysics,
Princeton University, Princeton, USA, 298 pp., 1992b.
Kipp, L. E., Charette, M. A., Moore, W. S., Henderson, P. B., and Rigor,
I. G.: Increased fluxes of shelf-derived materials to the central Arctic
Ocean, Sci. Adv., 4, eaao1302, https://doi.org/10.1126/sciadv.aao1302,
2018a.
Kipp, L. E., Sanial, V., Henderson, P. B., van Beek, P.,
Reyss, J.-L., Hammond, D. E., Moore, W. S., and Charette, M. A.: Radium isotopes
as tracers of hydrothermal inputs and neutrally buoyant plume dynamics in
the deep ocean, Mar. Chem., 201, 51–65, https://doi.org/10.1016/j.marchem.2017.06.011, 2018b.
Knauss, K. G., Ku, T. L., and Moore, W. S.: Radium and Thorium Isotopes in
Surface Waters of East Pacific and Coastal Southern-California, Earth
Planet. Sci. Lett., 39, 235–249, https://doi.org/10.1016/0012-821X(78)90199-1, 1978.
Ku, T. L. and Lin, M. C.: Ra-226 Distribution in Antarctic Ocean, Earth
Planet. Sci. Lett., 32, 236–248, https://doi.org/10.1016/0012-821X(76)90064-9, 1976.
Ku, T. L. and Luo, S.: Ocean circulation/mixing studies with decay-series
isotopes, in: U-Th Series Nuclides in Aquatic Systems, edited by:
Krishnaswami, S. and Cochran, J. K., Elsevier, Oxford, UK, 307–344, 2008.
Ku, T. L., Luo, S. D., Kusakabe, M., and Bishop, J. K. B.: Ra-228-Derived
Nutrient Budgets in the Upper Equatorial Pacific and the Role of New
Silicate in Limiting Productivity, Deep-Sea Res., 42, 479–497, https://doi.org/10.1016/0967-0645(95)00020-Q, 1995.
Kunze, E. and Sanford, T. B.: Abyssal mixing: Where it is not, J. Phys.
Oceanogr., 26, 2286–2296, https://doi.org/10.1175/1520-0485(1996)026<2286:AMWIIN>2.0.CO;2, 1996.
Kwon, E. Y., Kim, G., Primeau, F., Moore, W. S., Cho, H.-M., DeVries, T.,
Sarmiento, J. L., Charette, M. A., and Cho, Y.-K.: Global estimate of
submarine groundwater discharge based on an observationally constrained
radium isotope model, Geophys. Res. Lett., 41, 8438–8444, https://doi.org/10.1002/2014GL061574, 2014.
Lamontagne, S. and Webster, I. T.: Theoretical assessment of the effect of
vertical dispersivity on coastal seawater radium distribution, Front. Mar.
Sci., 6, 357, https://doi.org/10.3389/fmars.2019.00357, 2019.
Ledwell, J. R., Watson, A. J., and Law, C. S.: Evidence for slow mixing across
the pycnocline from an open-ocean tracer-release experiment, Nature, 364,
701–703, https://doi.org/10.1038/364701a0, 1993.
Le Gland, G., Mémery, L., Aumont, O., and Resplandy, L.: Improving the inverse modeling of a trace isotope: how precisely can radium-228 fluxes toward the ocean and submarine groundwater discharge be estimated?, Biogeosciences, 14, 3171–3189, https://doi.org/10.5194/bg-14-3171-2017, 2017.
Li, Y. H., Peng, T. H., Broecker, W. S., and Ostlund, H. G.: The Average Vertical
Mixing Coefficient for the Oceanic Thermocline, Tellus B, 36, 212–217, https://doi.org/10.3402/tellusb.v36i3.14905, 1984.
Liang, X., Spall, M., and Wunsch, C.: Global ocean vertical velocity from a
dynamically consistent ocean state estimate, J. Geophys.
Res.-Oceans, 122, 8208–8224, https://doi.org/10.1002/2017JC012985, 2017.
Lohan, M. C. and Tagliabue, A.: Oceanic Micronutrients: trace metals that are
essential for marine life, Elements, 14, 385–390, https://doi.org/10.2138/gselements.14.6.385, 2018.
Longhurst, A. R.: Ecological Geography of the Sea, Academic Press, Burlington, VT, USA, https://doi.org/10.1016/B978-0-12-455521-1.X5000-1, 2007.
Martin, A. P., Lucas, M. I., Painter, S. C., Pidcock, R., Prandke, H., Prandke,
H., and Stinchcombe, M. C.: The supply of nutrients due to vertical turbulent
mixing: a study at the Porcupine Abyssal Plain study site (49∘50′ N
16∘30′ W) in the Northeast Atlantic, Deep-Sea Res., 57,
1293–1302, https://doi.org/10.1016/j.dsr2.2010.01.006, 2010.
Menzel Barraqueta, J.-L., Klar, J. K., Gledhill, M., Schlosser, C., Shelley, R., Planquette, H. F., Wenzel, B., Sarthou, G., and Achterberg, E. P.: Atmospheric deposition fluxes over the Atlantic Ocean: a GEOTRACES case study, Biogeosciences, 16, 1525–1542, https://doi.org/10.5194/bg-16-1525-2019, 2019.
Moore, C. M., Mills, M. M., Arrigo, K. R., Berman-Frank, I., Bopp, L., Boyd,
P. W., Galbraith, E. D., Geider, R. J., Guieu, C., Jaccard, S. L., Jickells,
T. D., La Roche, J., Lenton, T. M., Mahowald, N. M., Earanon, E., Marinov, I.,
Moore, J. K., Nakatsuka, T., Oschlies, A., Saito, M. A., Thingstad, T. F.,
Tsuda, A., and Ulloa, O.: Processes and patterns of oceanic nutrient
limitation, Nat. Geosci., 6, 701–710, https://doi.org/10.1038/ngeo1765, 2013.
Moore, J. K., Doney, S. C., and Lindsay, K.: Upper ocean ecosystem dynamics and
iron cycling in a global three-dimensional model, Global Biogeochem.
Cy., 18, GB4028, https://doi.org/10.1029/2004GB002220, 2004.
Moore, W. S.: Determining coastal mixing rates using radium isotopes, Cont.
Shelf Res., 20, 1993–2007, https://doi.org/10.1016/S0278-4343(00)00054-6, 2000.
Moore, W. S.: Inappropriate attempts to use distributions of 228Ra and 226Ra
in coastal waters to model mixing and advection rates, Cont. Shelf Res.,
105, 95–100, https://doi.org/10.1016/j.csr.2015.05.014, 2015.
Moore, W. S. and Arnold, R.: Measurement of Ra-223 and Ra-224 in coastal
waters using a delayed coincidence counter, J. Geophys.
Res.-Oceans, 101, 1321–1329, https://doi.org/10.1029/95JC03139, 1996.
Moore, W. S. and Dymond, J.: Fluxes of Ra-226 and Barium in the Pacific-Ocean
– the Importance of Boundary Processes, Earth Planet. Sci. Lett.,
107, 55–68, https://doi.org/10.1016/0012-821X(91)90043-H, 1991.
Moore, W. S., Key, R. M., and Sarmiento, J. L.: Techniques for Precise Mapping
of Ra-226 and Ra-228 in the Ocean, J. Geophys. Res.-Oceans,
90, 6983–6994, https://doi.org/10.1029/JC090iC04p06983, 1985.
Moore, W. S., Sarmiento, J. L., and Key, R. M.: Submarine groundwater discharge
revealed by 228Ra distribution in the upper Atlantic Ocean, Nat.
Geosci., 1, 309–311, https://doi.org/10.1038/ngeo183, 2008.
Morel, F. M. M. and Price, N. M.: The biogeochemical cycles of trace metals in
the oceans, Science, 300, 944–947, https://doi.org/10.1126/science.1083545, 2003.
Nelson, G., Boyd, A. J., Agenbag, J. J., and Duncombe Rae, C. M.: An upwelling
filament north-west of Cape Town, South Africa, S. Afr. J.
Marine Sci., 19, 75–88, https://doi.org/10.2989/025776198784126953, 1998.
Noble, A. E., Lamborg, C. H, Ohnemus, D. C., Lam, P. J., Goepfert, T. J.,
Measures, C. I., Frame, C. H., Casciotti, K. L., DiTullio, G. R., Jennings, J.,
and Saito, M. A.: Basin-scale inputs of cobalt, iron, and manganese from the
Benguela-Angola front to the South Atlantic Ocean, Limnol.
Oceanogr., 57, 989–1010, https://doi.org/10.4319/lo.2012.57.4.0989, 2012.
Noble, A. E., Ohnemus, D. C., Hawco, N. J., Lam, P. J., and Saito, M. A.: Coastal sources, sinks and strong organic complexation of dissolved cobalt within the US North Atlantic GEOTRACES transect GA03, Biogeosciences, 14, 2715–2739, https://doi.org/10.5194/bg-14-2715-2017, 2017.
Nozaki, Y. and Yamamoto, Y.: Radium 228 based nitrate fluxes in the eastern
Indian Ocean and the South China Sea and a silicon-induced “alkalinity pump”
hypothesis, Global Biogeochem. Cy., 15, 555–567, https://doi.org/10.1029/2000GB001309, 2001.
Oschlies, A.: Nutrient supply to the surface waters of the North Atlantic: A
model study, J. Geophys. Res.-Oceans, 107, 3046, https://doi.org/10.1029/2000JC000275, 2002.
Owens, S. A., Pike, S., and Buesseler, K. O.: Thorium-234 as a tracer of
particle dynamics and upper ocean export in the Atlantic Ocean, Deep Sea
Res., 116, 42–59, https://doi.org/10.1016/j.dsr2.2014.11.010,
2015.
Painter, S. C., Henson, S. A., Forryan, A., Steigenberger, S., Klar, J., Stinchcombe, M. C., Rogan, N., Baker, A. R., Achterberg, E. P., and Moore, C. M.: An assessment of the vertical diffusive flux of iron and other nutrients to the surface waters of the subpolar North Atlantic Ocean, Biogeosciences, 11, 2113–2130, https://doi.org/10.5194/bg-11-2113-2014, 2014.
Paul, M., Van De Flierdt, T., Rehkämper, M., Khondoker, R., Weiss, D.,
Lohan, M. C., and Homoky, W. B.: Tracing the Agulhas leakage with lead isotopes,
Geophys. Res. Lett., 42, 8515–8521, https://doi.org/10.1002/2015GL065625, 2015.
Price, N. M. and Morel, F. M. M.: Cadmium and cobalt substitution for zinc in a
marine diatom, Nature, 344, 658–660, 1990.
Reid, D. F., Key, R. M., and Schink, D. R.: Radium, Thorium and Actinium
extraction from seawater using an improved manganese-oxide-coated fiber,
Earth Planet. Sci. Lett., 43, 223–226, https://doi.org/10.1016/0012-821X(79)90205-X, 1979.
Rigby, S. J., Williams, R. G., Achterberg, E. P., and Tagliabue, A.: Resource
availability and entrainment are driven by offsets between nutriclines and
winter mixed-layer depth, Global Biogeochem. Cy., 34, e2019GB006497,
https://doi.org/10.1029/2019GB006497, 2020.
Rijkenberg, M. J. A., Middag, R., Laan, P., Gerringa, L. J. A., van Aken, H. M.,
Schoemann, V., de Jong, J. T. M., and de Baar, H. J. W.: The distribution of
dissolved iron in the west Atlantic Ocean, PLoS One, 9, e101323, https://doi.org/10.1371/journal.pone.0101323, 2014.
Rodellas, V., Garcia-Orellana, J., Masqué, P., Feldman, M., and
Weinstein, Y.: Submarine groundwater discharge as a major source of
nutrients to the Mediterranean Sea, P. Natl. Acad. Sci., 12, 3926–3930,
https://doi.org/10.1073/pnas.1419049112, 2015.
Rutgers van der Loeff, M. M., Key, R. M., Scholten, J., Bauch, D., and
Michel, A.: 228Ra as a tracer for shelf water in the arctic ocean, Deep. Sea
Res., 42, 1533–1553, https://doi.org/10.1016/0967-0645(95)00053-4, 1995.
Saito, M. A., Noble, A. E., Tagliabue, A., Goepfert, T. J., Lamborg, C. H., and
Jenkins, W. J.: Slow-spreading submarine ridges in the South Atlantic as a
significant oceanic iron source, Nat. Geosci., 6, 775–779, https://doi.org/10.1038/ngeo1893, 2013.
Sanial, V., Kipp, L. E., Henderson, P. B., van Beek, P., Reyss, J.-L.,
Hammond, D. E., Hawco, N., Saito, M. A., Resing, J. A., Sedwick, P. N., Moore,
W. S., and Charette, M. A.: Radium-228 as a tracer of dissolved trace element
inputs from the Peruvian continental margin, Mar. Chem., 201, 20–34,
https://doi.org/10.1016/j.marchem.2017.05.008, 2018.
Sarmiento, J. L., Feely, H. W., Moore, W. S., Bainbridge, A. E., and Broecker,
W. S.: Relationship between Vertical Eddy Diffusion and Buoyancy Gradient in
Deep-Sea, Earth Planet. Sci. Lett., 32, 357–370, https://doi.org/10.1016/0012-821X(76)90076-5, 1976.
Sarmiento, J. L., Thiele, G., Key, R. M., and Moore, W. S.: Oxygen and Nitrate
New Production and Remineralization in the North-Atlantic Subtropical Gyre,
J. Geophys. Res.-Oceans, 95, 18303–18315, https://doi.org/10.1029/JC095iC10p18303, 1990.
Schlitzer, R.: Mass and Heat Transport in the South Atlantic Derived from
Historical Hydrographie Data, edited by: Wefer, G., Berger, W. H., Siedler, G., and Webb, D. J. , in: The South Atlantic, Springer, Berlin and Heidelberg, Germany, 305–323, https://doi.org/10.1007/978-3-642-80353-6_17, 1996.
Schlitzer, R.: Quantifying He fluxes from the mantle using multi-tracer data
assimilation, Philos. T. R. Soc. A, 374, 20150288, https://doi.org/10.1098/rsta.2015.0288, 2016.
Sunda, W. G. and Huntsman, S. A.: Cobalt and zinc interreplacement in marine
phytoplankton: Biological and geochemical implications, Limnol.
Oceanogr., 40, 1404–1417, https://doi.org/10.4319/lo.1995.40.8.1404, 1995.
Sunda, W. G. and Huntsman, S. A.: Interrelated influence of iron, light and
cell size on marine phytoplankton growth, Nature, 390, 389–392,
https://doi.org/10.1038/37093, 1997.
Sunda, W. G. and Huntsman, S. A.: Effect of Zn, Mn and Fe on Cd accumulation in
phytoplankton: Implications for oceanic Cd cycling, Limnol.
Oceanogr., 45, 1501–1516, https://doi.org/10.4319/lo.2000.45.7.1501,
2000.
Tagliabue, A., Sallee, J. B., Bowie, A. R., Levy, M., Swart, S., and Boyd,
P. W.: Surface-water iron supplies in the Southern Ocean sustained by deep
winter mixing, Nat. Geosci., 7, 314–320, https://doi.org/10.1038/Ngeo2101, 2014.
Thomalla, S., Turnewitsch, R., Lucas, M., and Poulton, A.: Particulate
organic carbon export from the North and South Atlantic gyres: the
234Th/238U disequilibrium approach, Deep Sea Res., 53, 1629–1648, https://doi.org/10.1016/j.dsr2.2006.05.018, 2006.
Urien, C. M. and Ewing, M.: Recent Sediments and Environment of Southern
Brazil, Uruguay, Buenos Aires, and Rio Negro Continental Shelf, in: The
Geology of Continental Margins, edited by: Burk, C. A. and Drake, C. L.,
Springer, Berlin and Heidelberg, Germany, 157–177, https://doi.org/10.1007/978-3-662-01141-6_12, 1974.
van Beek, P., Bourquin, M., Reyss, J.-L., Souhaut, M., Charette, M. A.,
and Jeande, C.: Radium isotopes to investigate the water mass pathways on
the Kerguelen Plateau (Southern Ocean), Deep-Sea Res., 55,
622–637, https://doi.org/10.1016/j.dsr2.2007.12.025, 2008.
Vieira, L. H., Krisch, S., Hopwood, M. J., Beck, A. J., Scholten, J.,
Liebetrau, V., and Achterberg, E. P.: Unprecedented Fe delivery from the
Congo River margin to the South Atlantic Gyre, Nat. Commun., 11, 556,
https://doi.org/10.1038/s41467-019-14255-2, 2020.
Windom, H. L., Moore, W. S., Niencheski, L. F. H., and Jahnke, R. A.: Submarine
groundwater discharge: a large, previously unrecognized source of dissolved
iron to the South Atlantic Ocean, Mar. Chem., 102, 252–266, https://doi.org/10.1016/j.marchem.2006.06.016, 2006.
Wyatt, N. J., Milne, A., Woodward, E. M. S., Rees, A. P., Browning, T. J.,
Bouman, H. A., Worsfold, P. J., and Lohan, M. C.: Biogeochemical cycling of
dissolved zinc along the GEOTRACES South Atlantic transect GA10 at
40∘S, Global Biogeochem. Cy., 28, 44–56, https://doi.org/10.1002/2013GB004637, 2014.
Wyatt, N. J., Milne, A., Achterberg, E. P., Browning, T. J., Bouman, H. A., Woodward, E. M. S., and Lohan, M. C.: Seasonal cycling of zinc and cobalt in the Southeast Atlantic along the GEOTRACES GA10 section, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2020-42, in review, 2020.
Yamada, M. and Nozaki, Y.: Radium Isotopes in Coastal and Open Ocean Surface
Waters of the Western North Pacific, Mar. Chem., 19, 379–389,
https://doi.org/10.1016/0304-4203(86)90057-5, 1986.
Short summary
The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions in the oceans, but the sources and fluxes of trace elements (TEs) to this region remain unclear. This study investigates seawater Ra-228 and provides important constraints on ocean mixing and dissolved TE fluxes to this region. Vertical mixing is a more important source than aeolian or shelf inputs in this region, but particulate or winter deep-mixing inputs may be required to balance the TE budgets.
The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions...
Altmetrics
Final-revised paper
Preprint