Articles | Volume 20, issue 24
https://doi.org/10.5194/bg-20-5003-2023
© Author(s) 2023. 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-20-5003-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
19 Dec 2023
Research article |
| 19 Dec 2023
| 19 Dec 2023
Revisiting the applicability and constraints of molybdenum- and uranium-based paleo redox proxies: comparing two contrasting sill fjords
Environmental Geochemistry Group, Department of Geography and Geosciences, Faculty of Science, University of Helsinki, Helsinki, 00560, Finland
Martijn Hermans
Environmental Geochemistry Group, Department of Geography and Geosciences, Faculty of Science, University of Helsinki, Helsinki, 00560, Finland
Baltic Sea Centre, Stockholm University, Stockholm, 114 18, Sweden
Sami A. Jokinen
Marine Geology, Geological Survey of Finland (GTK), Espoo, 02151, Finland
Inda Brinkmann
Department of Geology, Faculty of Science, Lund University, Lund, 223 62, Sweden
Department of Glaciology and Climate, Geological Survey of Denmark and Greenland, Copenhagen, 1350, Denmark
Helena L. Filipsson
Department of Geology, Faculty of Science, Lund University, Lund, 223 62, Sweden
Tom Jilbert
Environmental Geochemistry Group, Department of Geography and Geosciences, Faculty of Science, University of Helsinki, Helsinki, 00560, Finland
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Inda Brinkmann, Christine Barras, Tom Jilbert, Tomas Næraa, K. Mareike Paul, Magali Schweizer, and Helena L. Filipsson
Biogeosciences, 19, 2523–2535, https://doi.org/10.5194/bg-19-2523-2022, https://doi.org/10.5194/bg-19-2523-2022, 2022
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The concentration of the trace metal barium (Ba) in coastal seawater is a function of continental input, such as riverine discharge. Our geochemical records of the severely hot and dry year 2018, and following wet year 2019, reveal that prolonged drought imprints with exceptionally low Ba concentrations in benthic foraminiferal calcium carbonates of coastal sediments. This highlights the potential of benthic Ba / Ca to trace past climate extremes and variability in coastal marine records.
Margaret F. Williamson, Tom Jilbert, Alf Norkko, and Camilla Gustafsson
EGUsphere, https://doi.org/10.5194/egusphere-2025-2368, https://doi.org/10.5194/egusphere-2025-2368, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
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Reed bed carbon (C) storage is a topic of interest due to increased global distribution of reeds. C budgets to combat climate change often catalog reed beds as saltmarshes. Our findings show that reed beds are unique from saltmarshes, C storage is highest in reed bed sediments, and that reed bed zones may impact C storage. Further research into reed bed C is needed to better combat climate change and to ensure reeds are managed in a way that does not release excess C.
Lukas Jonkers, Tonke Strack, Montserrat Alonso-Garcia, Simon D'haenens, Robert Huber, Michal Kucera, Iván Hernández-Almeida, Chloe L. C. Jones, Brett Metcalfe, Rajeev Saraswat, Lóránd Silye, Sanjay K. Verma, Muhamad Naim Abd Malek, Gerald Auer, Cátia F. Barbosa, Maria A. Barcena, Karl-Heinz Baumann, Flavia Boscolo-Galazzo, Joeven Austine S. Calvelo, Lucilla Capotondi, Martina Caratelli, Jorge Cardich, Humberto Carvajal-Chitty, Markéta Chroustová, Helen K. Coxall, Renata M. de Mello, Anne de Vernal, Paula Diz, Kirsty M. Edgar, Helena L. Filipsson, Ángela Fraguas, Heather L. Furlong, Giacomo Galli, Natalia L. García Chapori, Robyn Granger, Jeroen Groeneveld, Adil Imam, Rebecca Jackson, David Lazarus, Julie Meilland, Marína Molčan Matejová, Raphael Morard, Caterina Morigi, Sven N. Nielsen, Diana Ochoa, Maria Rose Petrizzo, Andrés S. Rigual-Hernández, Marina C. Rillo, Matthew L. Staitis, Gamze Tanık, Raúl Tapia, Nishant Vats, Bridget S. Wade, and Anna E. Weinmann
J. Micropalaeontol., 44, 145–168, https://doi.org/10.5194/jm-44-145-2025, https://doi.org/10.5194/jm-44-145-2025, 2025
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Our study provides guidelines improving the reuse of marine microfossil assemblage data, which are valuable for understanding past ecosystems and environmental change. Based on a survey of 113 researchers, we identified key data attributes required for effective reuse. Analysis of a selection of datasets available online reveals a gap between the attributes scientists consider essential and the data currently available, highlighting the need for clearer data documentation and sharing practices.
Caroline P. Slomp, Martijn Hermans, Niels A. G. M. van Helmond, Silke Severmann, James McManus, Marit R. van Erk, and Sairah Malkin
EGUsphere, https://doi.org/10.5194/egusphere-2025-817, https://doi.org/10.5194/egusphere-2025-817, 2025
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Cable bacteria couple oxidation of sulfide at depth in sediments with reduction of oxygen, nitrate or nitrite near the sediment surface, thereby preventing release of toxic hydrogen sulfide to the overlying water. We show evidence for a diversity of cable bacteria in sediments from hypoxic and anoxic basins along the continental margin of California and Mexico. Cable bacteria activity in this setting is likely periodic and dependent on the supply of organic matter and/or oxygen.
Babette A.A. Hoogakker, Catherine Davis, Yi Wang, Stephanie Kusch, Katrina Nilsson-Kerr, Dalton S. Hardisty, Allison Jacobel, Dharma Reyes Macaya, Nicolaas Glock, Sha Ni, Julio Sepúlveda, Abby Ren, Alexandra Auderset, Anya V. Hess, Katrin J. Meissner, Jorge Cardich, Robert Anderson, Christine Barras, Chandranath Basak, Harold J. Bradbury, Inda Brinkmann, Alexis Castillo, Madelyn Cook, Kassandra Costa, Constance Choquel, Paula Diz, Jonas Donnenfield, Felix J. Elling, Zeynep Erdem, Helena L. Filipsson, Sebastián Garrido, Julia Gottschalk, Anjaly Govindankutty Menon, Jeroen Groeneveld, Christian Hallmann, Ingrid Hendy, Rick Hennekam, Wanyi Lu, Jean Lynch-Stieglitz, Lélia Matos, Alfredo Martínez-García, Giulia Molina, Práxedes Muñoz, Simone Moretti, Jennifer Morford, Sophie Nuber, Svetlana Radionovskaya, Morgan Reed Raven, Christopher J. Somes, Anja S. Studer, Kazuyo Tachikawa, Raúl Tapia, Martin Tetard, Tyler Vollmer, Xingchen Wang, Shuzhuang Wu, Yan Zhang, Xin-Yuan Zheng, and Yuxin Zhou
Biogeosciences, 22, 863–957, https://doi.org/10.5194/bg-22-863-2025, https://doi.org/10.5194/bg-22-863-2025, 2025
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Paleo-oxygen proxies can extend current records, constrain pre-anthropogenic baselines, provide datasets necessary to test climate models under different boundary conditions, and ultimately understand how ocean oxygenation responds on longer timescales. Here we summarize current proxies used for the reconstruction of Cenozoic seawater oxygen levels. This includes an overview of the proxy's history, how it works, resources required, limitations, and future recommendations.
Erik Gustafsson, Bo G. Gustafsson, Martijn Hermans, Christoph Humborg, and Christian Stranne
Geosci. Model Dev., 17, 7157–7179, https://doi.org/10.5194/gmd-17-7157-2024, https://doi.org/10.5194/gmd-17-7157-2024, 2024
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Methane (CH4) cycling in the Baltic Proper is studied through model simulations, enabling a first estimate of key CH4 fluxes. A preliminary budget identifies benthic CH4 release as the dominant source and two main sinks: CH4 oxidation in the water (92 % of sinks) and outgassing to the atmosphere (8 % of sinks). This study addresses CH4 emissions from coastal seas and is a first step toward understanding the relative importance of open-water outgassing compared with local coastal hotspots.
Inda Brinkmann, Christine Barras, Tom Jilbert, Tomas Næraa, K. Mareike Paul, Magali Schweizer, and Helena L. Filipsson
Biogeosciences, 19, 2523–2535, https://doi.org/10.5194/bg-19-2523-2022, https://doi.org/10.5194/bg-19-2523-2022, 2022
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The concentration of the trace metal barium (Ba) in coastal seawater is a function of continental input, such as riverine discharge. Our geochemical records of the severely hot and dry year 2018, and following wet year 2019, reveal that prolonged drought imprints with exceptionally low Ba concentrations in benthic foraminiferal calcium carbonates of coastal sediments. This highlights the potential of benthic Ba / Ca to trace past climate extremes and variability in coastal marine records.
Karol Kuliński, Gregor Rehder, Eero Asmala, Alena Bartosova, Jacob Carstensen, Bo Gustafsson, Per O. J. Hall, Christoph Humborg, Tom Jilbert, Klaus Jürgens, H. E. Markus Meier, Bärbel Müller-Karulis, Michael Naumann, Jørgen E. Olesen, Oleg Savchuk, Andreas Schramm, Caroline P. Slomp, Mikhail Sofiev, Anna Sobek, Beata Szymczycha, and Emma Undeman
Earth Syst. Dynam., 13, 633–685, https://doi.org/10.5194/esd-13-633-2022, https://doi.org/10.5194/esd-13-633-2022, 2022
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The paper covers the aspects related to changes in carbon, nitrogen, and phosphorus (C, N, P) external loads; their transformations in the coastal zone; changes in organic matter production (eutrophication) and remineralization (oxygen availability); and the role of sediments in burial and turnover of C, N, and P. Furthermore, this paper also focuses on changes in the marine CO2 system, the structure of the microbial community, and the role of contaminants for biogeochemical processes.
Constance Choquel, Emmanuelle Geslin, Edouard Metzger, Helena L. Filipsson, Nils Risgaard-Petersen, Patrick Launeau, Manuel Giraud, Thierry Jauffrais, Bruno Jesus, and Aurélia Mouret
Biogeosciences, 18, 327–341, https://doi.org/10.5194/bg-18-327-2021, https://doi.org/10.5194/bg-18-327-2021, 2021
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Marine microorganisms such as foraminifera are able to live temporarily without oxygen in sediments. In a Swedish fjord subjected to seasonal oxygen scarcity, a change in fauna linked to the decrease in oxygen and the increase in an invasive species was shown. The invasive species respire nitrate until 100 % of the nitrate porewater in the sediment and could be a major contributor to nitrogen balance in oxic coastal ecosystems. But prolonged hypoxia creates unfavorable conditions to survive.
Laurie M. Charrieau, Karl Ljung, Frederik Schenk, Ute Daewel, Emma Kritzberg, and Helena L. Filipsson
Biogeosciences, 16, 3835–3852, https://doi.org/10.5194/bg-16-3835-2019, https://doi.org/10.5194/bg-16-3835-2019, 2019
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We reconstructed environmental changes in the Öresund during the last 200 years, using foraminifera (microfossils), sediment, and climate data. Five zones were identified, reflecting oxygen, salinity, food content, and pollution levels for each period. The largest changes occurred ~ 1950, towards stronger currents. The foraminifera responded quickly (< 10 years) to the changes. Moreover, they did not rebound when the system returned to the previous pattern, but displayed a new equilibrium state.
Jeroen Groeneveld, Helena L. Filipsson, William E. N. Austin, Kate Darling, David McCarthy, Nadine B. Quintana Krupinski, Clare Bird, and Magali Schweizer
J. Micropalaeontol., 37, 403–429, https://doi.org/10.5194/jm-37-403-2018, https://doi.org/10.5194/jm-37-403-2018, 2018
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Current climate and environmental changes strongly affect shallow marine and coastal areas like the Baltic Sea. The combination of foraminiferal geochemistry and environmental parameters demonstrates that in a highly variable setting like the Baltic Sea, it is possible to separate different environmental impacts on the foraminiferal assemblages and therefore use chemical factors to reconstruct how seawater temperature, salinity, and oxygen varied in the past and may vary in the future.
Irina Polovodova Asteman, Helena L. Filipsson, and Kjell Nordberg
Clim. Past, 14, 1097–1118, https://doi.org/10.5194/cp-14-1097-2018, https://doi.org/10.5194/cp-14-1097-2018, 2018
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We present 2500 years of winter temperatures, using a sediment record from Gullmar Fjord analyzed for stable oxygen isotopes in benthic foraminifera. Reconstructed temperatures are within the annual temperature variability recorded in the fjord since the 1890s. Results show the warm Roman and Medieval periods and the cold Little Ice Age. The record also shows the recent warming, which does not stand out in the 2500-year perspective and is comparable to the Roman and Medieval climate anomalies.
Sami A. Jokinen, Joonas J. Virtasalo, Tom Jilbert, Jérôme Kaiser, Olaf Dellwig, Helge W. Arz, Jari Hänninen, Laura Arppe, Miia Collander, and Timo Saarinen
Biogeosciences, 15, 3975–4001, https://doi.org/10.5194/bg-15-3975-2018, https://doi.org/10.5194/bg-15-3975-2018, 2018
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Oxygen deficiency is a major environmental problem deteriorating seafloor habitats especially in the coastal ocean with large human impact. Here we apply a wide set of chemical and physical analyses to a 1500-year long sediment record and show that, although long-term climate variability has modulated seafloor oxygenation in the coastal northern Baltic Sea, the oxygen loss over the 20th century is unprecedentedly severe, emphasizing the need to reduce anthropogenic nutrient input in the future.
Tom Jilbert, Eero Asmala, Christian Schröder, Rosa Tiihonen, Jukka-Pekka Myllykangas, Joonas J. Virtasalo, Aarno Kotilainen, Pasi Peltola, Päivi Ekholm, and Susanna Hietanen
Biogeosciences, 15, 1243–1271, https://doi.org/10.5194/bg-15-1243-2018, https://doi.org/10.5194/bg-15-1243-2018, 2018
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Iron is a common dissolved element in river water, recognizable by its orange-brown colour. Here we show that when rivers reach the ocean much of this iron settles to the sediments by a process known as flocculation. The iron is then used by microbes in coastal sediments, which are important hotspots in the global carbon cycle.
Laurie M. Charrieau, Lene Bryngemark, Ingemar Hansson, and Helena L. Filipsson
J. Micropalaeontol., 37, 191–194, https://doi.org/10.5194/jm-37-191-2018, https://doi.org/10.5194/jm-37-191-2018, 2018
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Splitting samples into smaller subsamples is often necessary in micropalaeontological studies. Indeed, the general high abundance of microfossils – which makes them excellent tools to reconstruct past environments – also results in very time-consuming faunal analyses. Here we present an improved and cost-effective wet splitter for micropalaeontological samples aimed to reduce picking time, while keeping information loss to a minimum.
Ulrich Kotthoff, Jeroen Groeneveld, Jeanine L. Ash, Anne-Sophie Fanget, Nadine Quintana Krupinski, Odile Peyron, Anna Stepanova, Jonathan Warnock, Niels A. G. M. Van Helmond, Benjamin H. Passey, Ole Rønø Clausen, Ole Bennike, Elinor Andrén, Wojciech Granoszewski, Thomas Andrén, Helena L. Filipsson, Marit-Solveig Seidenkrantz, Caroline P. Slomp, and Thorsten Bauersachs
Biogeosciences, 14, 5607–5632, https://doi.org/10.5194/bg-14-5607-2017, https://doi.org/10.5194/bg-14-5607-2017, 2017
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We present reconstructions of paleotemperature, paleosalinity, and paleoecology from the Little Belt (Site M0059) over the past ~ 8000 years and evaluate the applicability of numerous proxies. Conditions were lacustrine until ~ 7400 cal yr BP. A transition to brackish–marine conditions then occurred within ~ 200 years. Salinity proxies rarely allowed quantitative estimates but revealed congruent results, while quantitative temperature reconstructions differed depending on the proxies used.
Jukka-Pekka Myllykangas, Tom Jilbert, Gunnar Jakobs, Gregor Rehder, Jan Werner, and Susanna Hietanen
Earth Syst. Dynam., 8, 817–826, https://doi.org/10.5194/esd-8-817-2017, https://doi.org/10.5194/esd-8-817-2017, 2017
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The deep waters of the Baltic Sea host an expanding
dead zone, where low-oxygen conditions favour the natural production of two strong greenhouse gases, methane and nitrous oxide. Oxygen is introduced into the deeps only during rare
salt pulses. We studied the effects of a recent salt pulse on Baltic greenhouse gas production. We found that where oxygen was introduced, methane was largely removed, while nitrous oxide production increased, indicating strong effects on greenhouse gas dynamics.
Wenxin Ning, Jing Tang, and Helena L. Filipsson
Earth Surf. Dynam., 4, 773–780, https://doi.org/10.5194/esurf-4-773-2016, https://doi.org/10.5194/esurf-4-773-2016, 2016
Matthias Egger, Peter Kraal, Tom Jilbert, Fatimah Sulu-Gambari, Célia J. Sapart, Thomas Röckmann, and Caroline P. Slomp
Biogeosciences, 13, 5333–5355, https://doi.org/10.5194/bg-13-5333-2016, https://doi.org/10.5194/bg-13-5333-2016, 2016
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By combining detailed geochemical analyses with diagenetic modeling, we provide new insights into how methane dynamics may strongly overprint burial records of iron, sulfur and phosphorus in marine systems subject to changes in organic matter loading or water column salinity. A better understanding of these processes will improve our ability to read ancient sediment records and thus to predict the potential consequences of global warming and human-enhanced inputs of nutrients to the ocean.
J. M. Bernhard, W. G. Phalen, A. McIntyre-Wressnig, F. Mezzo, J. C. Wit, M. Jeglinski, and H. L. Filipsson
Biogeosciences, 12, 5515–5522, https://doi.org/10.5194/bg-12-5515-2015, https://doi.org/10.5194/bg-12-5515-2015, 2015
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We present an innovative method using osmotic pumps and the fluorescent marker calcein to help identify where and when calcareous bottom-dwelling organisms mineralize in sediments. These organisms, and their geochemical signatures in their carbonate, are the ocean’s storytellers helping us understand past marine conditions. For many species, the timing and location of their calcite growth is not known. Knowing this will enable us to reconstruct past marine environments with greater accuracy.
C. L. McKay, J. Groeneveld, H. L. Filipsson, D. Gallego-Torres, M. J. Whitehouse, T. Toyofuku, and O.E. Romero
Biogeosciences, 12, 5415–5428, https://doi.org/10.5194/bg-12-5415-2015, https://doi.org/10.5194/bg-12-5415-2015, 2015
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We highlight the proxy potential of foraminiferal Mn/Ca determined by secondary ion mass spectrometry and flow-through inductively coupled plasma optical emission spectroscopy for recording changes in bottom-water oxygen conditions. Comparisons with Mn sediment bulk measurements from the same sediment core largely agree with the results. High foraminiferal Mn/Ca occurs in samples from times of high productivity export and corresponds with the benthic foraminiferal faunal composition.
C. Lenz, T. Jilbert, D.J. Conley, M. Wolthers, and C.P. Slomp
Biogeosciences, 12, 4875–4894, https://doi.org/10.5194/bg-12-4875-2015, https://doi.org/10.5194/bg-12-4875-2015, 2015
M. P. Nardelli, C. Barras, E. Metzger, A. Mouret, H. L. Filipsson, F. Jorissen, and E. Geslin
Biogeosciences, 11, 4029–4038, https://doi.org/10.5194/bg-11-4029-2014, https://doi.org/10.5194/bg-11-4029-2014, 2014
J. Groeneveld and H. L. Filipsson
Biogeosciences, 10, 5125–5138, https://doi.org/10.5194/bg-10-5125-2013, https://doi.org/10.5194/bg-10-5125-2013, 2013
B. C. Lougheed, H. L. Filipsson, and I. Snowball
Clim. Past, 9, 1015–1028, https://doi.org/10.5194/cp-9-1015-2013, https://doi.org/10.5194/cp-9-1015-2013, 2013
I. Polovodova Asteman, K. Nordberg, and H. L. Filipsson
Biogeosciences, 10, 1275–1290, https://doi.org/10.5194/bg-10-1275-2013, https://doi.org/10.5194/bg-10-1275-2013, 2013
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Long-term variations in pH in coastal waters along the Korean Peninsula
The effect of carbonate mineral additions on biogeochemical conditions in surface sediments and benthic–pelagic exchange fluxes
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The influence of zooplankton and oxygen on the particulate organic carbon flux in the Benguela Upwelling System
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Temperature-enhanced effects of iron on Southern Ocean phytoplankton
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The Northeast Greenland Shelf as a potential late-summer CO2 source to the atmosphere
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Quantification and mitigation of bottom-trawling impacts on sedimentary organic carbon stocks in the North Sea
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Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
Hypoxia also occurs in small highly turbid estuaries: the example of the Charente (Bay of Biscay)
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
Oceanographic processes driving low-oxygen conditions inside Patagonian fjords
Above- and belowground plant mercury dynamics in a salt marsh estuary in Massachusetts, USA
Variability and drivers of carbonate chemistry at shellfish aquaculture sites in the Salish Sea, British Columbia
Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters
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Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
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Uncertainty in the evolution of northwestern North Atlantic circulation leads to diverging biogeochemical projections
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Vlad A. Macovei, Louise C. V. Rewrie, Rüdiger Röttgers, and Yoana G. Voynova
Biogeosciences, 22, 3375–3396, https://doi.org/10.5194/bg-22-3375-2025, https://doi.org/10.5194/bg-22-3375-2025, 2025
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We found that biogeochemical variability at the land–sea interface (LSI) in two major temperate estuaries is modulated by the 14 d spring–neap tidal cycle, with large effects on dissolved inorganic and organic carbon concentrations and distribution. As this effect increases the strength of the carbon source to the atmosphere by up to 74 % during spring tide, it should be accounted for in regional models, which aim to resolve biogeochemical processing at the LSI.
David Curbelo-Hernández, David González-Santana, Aridane G. González, J. Magdalena Santana-Casiano, and Melchor González-Dávila
Biogeosciences, 22, 3329–3356, https://doi.org/10.5194/bg-22-3329-2025, https://doi.org/10.5194/bg-22-3329-2025, 2025
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This study offers a unique high-resolution dataset (2019–2024) on surface physicochemical properties in the western Mediterranean Sea. It reveals accelerated surface warming, significantly altering CO2 levels and pH. Currently a net CO2 sink, the region may become a CO2 source by 2030 due to weakening in-gassing. The research highlights the value of VOS (volunteer observing ship) lines for monitoring climate impacts and emphasizes the need for ongoing observations to enhance long-term trend accuracy and future projections.
Darren J. Pilcher, Jessica N. Cross, Natalie Monacci, Linquan Mu, Kelly A. Kearney, Albert J. Hermann, and Wei Cheng
Biogeosciences, 22, 3103–3125, https://doi.org/10.5194/bg-22-3103-2025, https://doi.org/10.5194/bg-22-3103-2025, 2025
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The Bering Sea shelf is a highly productive marine ecosystem that is vulnerable to ocean acidification. We use a computational model to simulate the carbon cycle and acidification rates from 1970–2022. The results suggest that bottom water acidification rates are more than twice as great as surface rates. Bottom waters are also naturally more acidic. Thus these waters will pass key thresholds known to negatively impact marine organisms, such as red king crab, much sooner than surface waters.
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
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Coastal and shelf sediments are the most important sinks for organic carbon (OC) on Earth. We produced a new high-resolution sediment and 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.
Menghong Dong, Xinyu Guo, Takuya Matsuura, Taichi Tebakari, and Jing Zhang
Biogeosciences, 22, 2383–2402, https://doi.org/10.5194/bg-22-2383-2025, https://doi.org/10.5194/bg-22-2383-2025, 2025
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Submarine groundwater discharge (SGD), a common coastal hydrological process that involves submarine inflow of groundwater into the sea, is associated with a large nutrient load. To clarify the distribution of SGD-derived nutrients after release at the bottom of the sea and their contribution to phytoplankton growth in the marine ecosystem, we modeled the SGD process in Toyama Bay using a specialized computer code that can distinguish SGD-derived nutrients from nutrients from other sources.
M. Celeste López-Abbate, John E. Garzón-Cardona, Ricardo Silva, Juan-Carlos Molinero, Laura A. Ruiz-Etcheverry, Ana M. Martínez, Azul S. Gilabert, and Rubén J. Lara
Biogeosciences, 22, 2309–2325, https://doi.org/10.5194/bg-22-2309-2025, https://doi.org/10.5194/bg-22-2309-2025, 2025
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This study explores how microbial dynamics influence the dissolved organic matter (DOM) pool in the Patagonian Shelf. Despite high phytoplankton biomass, selective grazing on fast-growing bacteria led to DOM accumulation, likely due to reduced DOM-consuming bacteria and added egestion compounds. Experiments showed that bacteria not only acted as a carbon sink through mineralization but also transferred assimilated carbon dioxide (CO2) to higher trophic levels.
Librada Ramírez, Leonardo J. Pozzo-Pirotta, Aja Trebec, Víctor Manzanares-Vázquez, José L. Díez, Javier Arístegui, Ulf Riebesell, Stephen D. Archer, and María Segovia
Biogeosciences, 22, 1865–1886, https://doi.org/10.5194/bg-22-1865-2025, https://doi.org/10.5194/bg-22-1865-2025, 2025
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We studied the potential effects of increasing ocean alkalinity on a natural plankton community in subtropical waters of the Atlantic near Gran Canaria, Spain. Alkalinity is the capacity of water to resist acidification, and plankton are usually microscopic plants (phytoplankton) and animals (zooplankton), often less than 2.5 cm in length. This study suggests that increasing ocean alkalinity did not have a significant negative impact on the plankton community studied.
Leissing Frederick, Mauricio A. Urbina, and Ruben Escribano
Biogeosciences, 22, 1839–1852, https://doi.org/10.5194/bg-22-1839-2025, https://doi.org/10.5194/bg-22-1839-2025, 2025
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Evidence shows that due to global warming, zooplankton inhabiting the coastal upwelling zone are exposed to increasing hypoxia affecting their physiology, metabolism, and population dynamics. The adaptive responses of zooplankton to cope with mild/severe hypoxia may depend on trade-offs with other metabolic/energy demands, implying less energy for growth, feeding, and reproduction, with ecological consequences for the zooplankton population and the marine food web.
Sören Iwe, Oliver Schmale, and Bernd Schneider
Biogeosciences, 22, 1767–1779, https://doi.org/10.5194/bg-22-1767-2025, https://doi.org/10.5194/bg-22-1767-2025, 2025
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We present a novel method for quantifying N2 fixation by cyanobacteria, which is crucial in Baltic Sea eutrophication. Our Gas Equilibrium – Membrane-Inlet Mass Spectrometer (GE-MIMS), designed for operation on voluntary observing ships (VOSs), enables large-scale monitoring of surface water N2 depletion caused by N2 fixation. Laboratory tests confirm the device’s accuracy and precision, ensuring that it can complement current methods and contribute valuable data for better understanding N2 fixation in the Baltic Sea.
Caroline P. Slomp, Martijn Hermans, Niels A. G. M. van Helmond, Silke Severmann, James McManus, Marit R. van Erk, and Sairah Malkin
EGUsphere, https://doi.org/10.5194/egusphere-2025-817, https://doi.org/10.5194/egusphere-2025-817, 2025
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Cable bacteria couple oxidation of sulfide at depth in sediments with reduction of oxygen, nitrate or nitrite near the sediment surface, thereby preventing release of toxic hydrogen sulfide to the overlying water. We show evidence for a diversity of cable bacteria in sediments from hypoxic and anoxic basins along the continental margin of California and Mexico. Cable bacteria activity in this setting is likely periodic and dependent on the supply of organic matter and/or oxygen.
Jenna Alyson Lee, Joseph H. Vineis, Mathieu A. Poupon, Laure Resplandy, and Bess B. Ward
EGUsphere, https://doi.org/10.5194/egusphere-2025-871, https://doi.org/10.5194/egusphere-2025-871, 2025
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Concurrent sampling of environmental parameters, productivity rates, photopigments, and DNA were used to analyze a 24–L estuarine diatom bloom microcosm. Biogeochemical data and an ecological model indicated that the bloom was terminated by grazing. Comparisons to previous studies revealed (1) additional community and diversity complexity using 18S amplicon vs. traditional pigment–based analyses, and (2) a potential global productivity–diversity relationship using 18S and carbon transport rates.
Yong-Woo Lee, Mi-Ok Park, Seong-Gil Kim, Tae-Hoon Kim, Yong Hwa Oh, Sang Heon Lee, and DongJoo Joung
Biogeosciences, 22, 675–690, https://doi.org/10.5194/bg-22-675-2025, https://doi.org/10.5194/bg-22-675-2025, 2025
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Long-term pH variation in coastal waters along the Korean Peninsula was assessed for the first time, and it exhibited no significant pH change over an 11-year period. This contrasts with the ongoing pH decline in open oceans and other coastal areas. Analysis of environmental data showed that pH is mainly controlled by dissolved oxygen in bottom waters. This suggests that ocean warming could cause a pH decline in Korean coastal waters, affecting many fish and seaweed aquaculture operations.
Kadir Biçe, Tristen Myers Stewart, George G. Waldbusser, and Christof Meile
Biogeosciences, 22, 641–657, https://doi.org/10.5194/bg-22-641-2025, https://doi.org/10.5194/bg-22-641-2025, 2025
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We studied the effect of addition of carbonate minerals on coastal sediments. We carried out laboratory experiments to quantify the dissolution kinetics and integrated these observations into a numerical model that describes biogeochemical cycling in surficial sediments. Using the model, we demonstrate the buffering effect of the mineral additions and their duration. We quantify the effect under different environmental conditions and assess the potential for increased atmospheric CO2 uptake.
Feifei Liu, Ute Daewel, Jan Kossack, Kubilay Timur Demir, Helmuth Thomas, and Corinna Schrum
EGUsphere, https://doi.org/10.5194/egusphere-2025-81, https://doi.org/10.5194/egusphere-2025-81, 2025
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Ocean Alkalinity Enhancement boosts oceanic CO₂ absorption, offering a climate solution. Using a regional model, we examined OAE in the North Sea, revealing that shallow coastal areas achieve higher CO₂ uptake than offshore, where alkalinity is more susceptible to deep-ocean loss. Long-term carbon storage is limited, and pH shifts vary by location. Our findings guide OAE deployment to optimize carbon removal while minimizing ecological effects, supporting global climate mitigation efforts.
Mariche Bandibas Natividad, Jian-Jhih Chen, Hsin-Yu Chou, Lan-Feng Fan, Yi-Le Shen, and Wen-Chen Chou
EGUsphere, https://doi.org/10.5194/egusphere-2024-4000, https://doi.org/10.5194/egusphere-2024-4000, 2025
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Seagrass restoration serves as a nature-based solution for CO2 removal. We examined the organic carbon and carbonate dynamics of restored seagrasses (SG) and bare sediments (BS) using ex situ core incubations. SG exhibited higher net ecosystem metabolism compared to BS, while no significant difference was observed in net ecosystem calcification. Consequently, SG demonstrated a significantly enhanced overall capacity for carbon uptake.
Jessica L. Oberlander, Mackenzie E. Burke, Cat A. London, and Hugh L. MacIntyre
Biogeosciences, 22, 499–512, https://doi.org/10.5194/bg-22-499-2025, https://doi.org/10.5194/bg-22-499-2025, 2025
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Ocean alkalinity enhancement (OAE) is a promising negative emission technology that results in the net sequestration of atmospheric carbon. In this paper, we assess the potential impact of OAE on phytoplankton through an analysis of prior studies and the effects of simulated OAE on photosynthetic competence. Our findings suggest that there may be little if any significant impact on most phytoplankton studied to date if OAE is conducted in well-flushed, nearshore environments.
Laura Marín-Samper, Javier Arístegui, Nauzet Hernández-Hernández, and Ulf Riebesell
Biogeosciences, 21, 5707–5724, https://doi.org/10.5194/bg-21-5707-2024, https://doi.org/10.5194/bg-21-5707-2024, 2024
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This study exposed a natural community to two non-CO2-equilibrated ocean alkalinity enhancement (OAE) deployments using different minerals. Adding alkalinity in this manner decreases dissolved CO2, essential for photosynthesis. While photosynthesis was not suppressed, bloom formation was mildly delayed, potentially impacting marine food webs. The study emphasizes the need for further research on OAE without prior equilibration and on its ecological implications.
Riss M. Kell, Rebecca J. Chmiel, Deepa Rao, Dawn M. Moran, Matthew R. McIlvin, Tristan J. Horner, Nicole L. Schanke, Ichiko Sugiyama, Robert B. Dunbar, Giacomo R. DiTullio, and Mak A. Saito
Biogeosciences, 21, 5685–5706, https://doi.org/10.5194/bg-21-5685-2024, https://doi.org/10.5194/bg-21-5685-2024, 2024
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Despite interest in modeling the biogeochemical uptake and cycling of the trace metal zinc (Zn), measurements of Zn uptake in natural marine phytoplankton communities have not been conducted previously. To fill this gap, we employed a stable isotope uptake rate measurement method to quantify Zn uptake into natural phytoplankton assemblages within the Southern Ocean. Zn demand was high and rapid enough to depress the inventory of Zn available to phytoplankton on seasonal timescales.
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
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Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Michael R. Roman, Andrew H. Altieri, Denise Breitburg, Erica M. Ferrer, Natalya D. Gallo, Shin-ichi Ito, Karin Limburg, Kenneth Rose, Moriaki Yasuhara, and Lisa A. Levin
Biogeosciences, 21, 4975–5004, https://doi.org/10.5194/bg-21-4975-2024, https://doi.org/10.5194/bg-21-4975-2024, 2024
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Oxygen-depleted ocean waters have increased worldwide. In order to improve our understanding of the impacts of this oxygen loss on marine life it is essential that we develop reliable indicators that track the negative impacts of low oxygen. We review various indicators of low-oxygen stress for marine animals including their use, research needs, and application to confront the challenges of ocean oxygen loss.
Charlotte Eich, Mathijs van Manen, J. Scott P. McCain, Loay J. Jabre, Willem H. van de Poll, Jinyoung Jung, Sven B. E. H. Pont, Hung-An Tian, Indah Ardiningsih, Gert-Jan Reichart, Erin M. Bertrand, Corina P. D. Brussaard, and Rob Middag
Biogeosciences, 21, 4637–4663, https://doi.org/10.5194/bg-21-4637-2024, https://doi.org/10.5194/bg-21-4637-2024, 2024
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Phytoplankton growth in the Southern Ocean (SO) is often limited by low iron (Fe) concentrations. Sea surface warming impacts Fe availability and can affect phytoplankton growth. We used shipboard Fe clean incubations to test how changes in Fe and temperature affect SO phytoplankton. Their abundances usually increased with Fe addition and temperature increase, with Fe being the major factor. These findings imply potential shifts in ecosystem structure, impacting food webs and elemental cycling.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 21, 4469–4493, https://doi.org/10.5194/bg-21-4469-2024, https://doi.org/10.5194/bg-21-4469-2024, 2024
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Marine biological production is highly dependent on the availability of nitrogen and phosphorus. Rivers are the main source of phosphorus to the oceans but poorly represented in global model oceans. We include dissolved nitrogen and phosphorus from river export in a global model ocean and find that the addition of riverine phosphorus affects marine biology on millennial timescales more than riverine nitrogen alone. Globally, riverine phosphorus input increases primary production rates.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Marchiano Holding, and Søren Rysgaard
Biogeosciences, 21, 4037–4050, https://doi.org/10.5194/bg-21-4037-2024, https://doi.org/10.5194/bg-21-4037-2024, 2024
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In this work, we measured the chemistry of seawater from samples obtained from different depths and locations off the east coast of the Northeast Greenland National Park to determine what is influencing concentrations of dissolved CO2. Historically, the region has always been thought to take up CO2 from the atmosphere, but we show that it is possible for the region to become a source in late summer. We discuss the variables that may be related to such changes.
Lennart Thomas Bach, Aaron James Ferderer, Julie LaRoche, and Kai Georg Schulz
Biogeosciences, 21, 3665–3676, https://doi.org/10.5194/bg-21-3665-2024, https://doi.org/10.5194/bg-21-3665-2024, 2024
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Ocean alkalinity enhancement (OAE) is an emerging marine CO2 removal method, but its environmental effects are insufficiently understood. The OAE Pelagic Impact Intercomparison Project (OAEPIIP) provides funding for a standardized and globally replicated microcosm experiment to study the effects of OAE on plankton communities. Here, we provide a detailed manual for the OAEPIIP experiment. We expect OAEPIIP to help build scientific consensus on the effects of OAE on plankton.
Marlena Szeligowska, Déborah Benkort, Anna Przyborska, Mateusz Moskalik, Bernabé Moreno, Emilia Trudnowska, and Katarzyna Błachowiak-Samołyk
Biogeosciences, 21, 3617–3639, https://doi.org/10.5194/bg-21-3617-2024, https://doi.org/10.5194/bg-21-3617-2024, 2024
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The European Arctic is experiencing rapid regional warming, causing glaciers that terminate in the sea to retreat onto land. Due to this process, the area of a well-studied fjord, Hornsund, has increased by around 100 km2 (40%) since 1976. Combining satellite and in situ data with a mathematical model, we estimated that, despite some negative consequences of glacial meltwater release, such emerging coastal waters could mitigate climate change by increasing carbon uptake and storage by sediments.
Mallory C. Ringham, Nathan Hirtle, Cody Shaw, Xi Lu, Julian Herndon, Brendan R. Carter, and Matthew D. Eisaman
Biogeosciences, 21, 3551–3570, https://doi.org/10.5194/bg-21-3551-2024, https://doi.org/10.5194/bg-21-3551-2024, 2024
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Ocean alkalinity enhancement leverages the large surface area and carbon storage capacity of the oceans to store atmospheric CO2 as dissolved bicarbonate. We monitored CO2 uptake in seawater treated with NaOH to establish operational boundaries for carbon removal experiments. Results show that CO2 equilibration occurred on the order of weeks to months, was consistent with values expected from equilibration calculations, and was limited by mineral precipitation at high pH and CaCO3 saturation.
Riel Carlo O. Ingeniero, Gesa Schulz, and Hermann W. Bange
Biogeosciences, 21, 3425–3440, https://doi.org/10.5194/bg-21-3425-2024, https://doi.org/10.5194/bg-21-3425-2024, 2024
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Our research is the first to measure dissolved NO concentrations in temperate estuarine waters, providing insights into its distribution under varying conditions and enhancing our understanding of its production processes. Dissolved NO was supersaturated in the Elbe Estuary, indicating that it is a source of atmospheric NO. The observed distribution of dissolved NO most likely resulted from nitrification.
Weiyi Tang, Jeff Talbott, Timothy Jones, and Bess B. Ward
Biogeosciences, 21, 3239–3250, https://doi.org/10.5194/bg-21-3239-2024, https://doi.org/10.5194/bg-21-3239-2024, 2024
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Wastewater treatment plants (WWTPs) are known to be hotspots of greenhouse gas emissions. However, the impact of WWTPs on the emission of the greenhouse gas N2O in downstream aquatic environments is less constrained. We found spatially and temporally variable but overall higher N2O concentrations and fluxes in waters downstream of WWTPs, pointing to the need for efficient N2O removal in addition to the treatment of nitrogen in WWTPs.
Deep S. Banerjee and Jozef Skakala
EGUsphere, https://doi.org/10.22541/essoar.171405637.76928549/v1, https://doi.org/10.22541/essoar.171405637.76928549/v1, 2024
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Nitrate is a crucial nutrient in oceans. Excess nutrients can trigger uncontrolled algae growth (eutrophication), damaging marine ecosystems. We used a machine learning tool to generate a skilled, gap-free, bi-decadal surface nitrate dataset from sparse observations. This dataset reveals areas on the North West European Shelf at risk of eutrophication, bi-decadal trends in coastal nitrate, and an impact of winter nitrate on spring phytoplankton blooms.
Amanda Y. L. Cheong, Kogila Vani Annammala, Ee Ling Yong, Yongli Zhou, Robert S. Nichols, and Patrick Martin
Biogeosciences, 21, 2955–2971, https://doi.org/10.5194/bg-21-2955-2024, https://doi.org/10.5194/bg-21-2955-2024, 2024
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We measured nutrients and dissolved organic matter for 1 year in a eutrophic tropical estuary to understand their sources and cycling. Our data show that the dissolved organic matter originates partly from land and partly from microbial processes in the water. Internal recycling is likely important for maintaining high nutrient concentrations, and we found that there is often excess nitrogen compared to silicon and phosphorus. Our data help to explain how eutrophication persists in this system.
Aaron Ferderer, Kai G. Schulz, Ulf Riebesell, Kirralee G. Baker, Zanna Chase, and Lennart T. Bach
Biogeosciences, 21, 2777–2794, https://doi.org/10.5194/bg-21-2777-2024, https://doi.org/10.5194/bg-21-2777-2024, 2024
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Ocean alkalinity enhancement (OAE) is a promising method of atmospheric carbon removal; however, its ecological impacts remain largely unknown. We assessed the effects of simulated silicate- and calcium-based mineral OAE on diatom silicification. We found that increased silicate concentrations from silicate-based OAE increased diatom silicification. In contrast, the enhancement of alkalinity had no effect on community silicification and minimal effects on the silicification of different genera.
David González-Santana, María Segovia, Melchor González-Dávila, Librada Ramírez, Aridane G. González, Leonardo J. Pozzo-Pirotta, Veronica Arnone, Victor Vázquez, Ulf Riebesell, and J. Magdalena Santana-Casiano
Biogeosciences, 21, 2705–2715, https://doi.org/10.5194/bg-21-2705-2024, https://doi.org/10.5194/bg-21-2705-2024, 2024
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In a recent experiment off the coast of Gran Canaria (Spain), scientists explored a method called ocean alkalinization enhancement (OAE), where carbonate minerals were added to seawater. This process changed the levels of certain ions in the water, affecting its pH and buffering capacity. The researchers were particularly interested in how this could impact the levels of essential trace metals in the water.
Lucas Porz, Wenyan Zhang, Nils Christiansen, Jan Kossack, Ute Daewel, and Corinna Schrum
Biogeosciences, 21, 2547–2570, https://doi.org/10.5194/bg-21-2547-2024, https://doi.org/10.5194/bg-21-2547-2024, 2024
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Seafloor sediments store a large amount of carbon, helping to naturally regulate Earth's climate. If disturbed, some sediment particles can turn into CO2, but this effect is not well understood. Using computer simulations, we found that bottom-contacting fishing gears release about 1 million tons of CO2 per year in the North Sea, one of the most heavily fished regions globally. We show how protecting certain areas could reduce these emissions while also benefitting seafloor-living animals.
Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
Biogeosciences, 21, 2335–2354, https://doi.org/10.5194/bg-21-2335-2024, https://doi.org/10.5194/bg-21-2335-2024, 2024
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Ocean alkalinity enhancement aims to increase atmospheric CO2 sequestration by adding alkaline materials to the ocean. We assessed the environmental effects of olivine and steel slag powder on coastal plankton. Overall, slag is more efficient than olivine in releasing total alkalinity and, thus, in its ability to sequester CO2. Slag also had less environmental effect on the enclosed plankton communities when considering its higher CO2 removal potential based on this 3-week experiment.
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
Biogeosciences, 21, 2143–2158, https://doi.org/10.5194/bg-21-2143-2024, https://doi.org/10.5194/bg-21-2143-2024, 2024
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This work shows that, under a high-emission scenario, oxygen concentration in deep water of parts of the North Sea and Celtic Sea can become critically low (hypoxia) towards the end of this century. The extent and frequency of hypoxia depends on the intensity of climate change projected by different climate models. This is the result of a complex combination of factors like warming, increase in stratification, changes in the currents and changes in biological processes.
Sandy E. Tenorio and Laura Farías
Biogeosciences, 21, 2029–2050, https://doi.org/10.5194/bg-21-2029-2024, https://doi.org/10.5194/bg-21-2029-2024, 2024
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Time series studies show that CH4 is highly dynamic on the coastal ocean surface and planktonic communities are linked to CH4 accumulation, as found in coastal upwelling off Chile. We have identified the crucial role of picoplankton (> 3 µm) in CH4 recycling, especially with the addition of methylated substrates (trimethylamine and methylphosphonic acid) during upwelling and non-upwelling periods. These insights improve understanding of surface ocean CH4 recycling, aiding CH4 emission estimates.
Charlotte A. J. Williams, Tom Hull, Jan Kaiser, Claire Mahaffey, Naomi Greenwood, Matthew Toberman, and Matthew R. Palmer
Biogeosciences, 21, 1961–1971, https://doi.org/10.5194/bg-21-1961-2024, https://doi.org/10.5194/bg-21-1961-2024, 2024
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Oxygen (O2) is a key indicator of ocean health. The risk of O2 loss in the productive coastal/continental slope regions is increasing. Autonomous underwater vehicles equipped with O2 optodes provide lots of data but have problems resolving strong vertical O2 changes. Here we show how to overcome this and calculate how much O2 is supplied to the low-O2 bottom waters via mixing. Bursts in mixing supply nearly all of the O2 to bottom waters in autumn, stopping them reaching ecologically low levels.
Sabine Schmidt and Ibrahima Iris Diallo
Biogeosciences, 21, 1785–1800, https://doi.org/10.5194/bg-21-1785-2024, https://doi.org/10.5194/bg-21-1785-2024, 2024
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Along the French coast facing the Bay of Biscay, the large Gironde and Loire estuaries suffer from hypoxia. This prompted a study of the small Charente estuary located between them. This work reveals a minimum oxygen zone in the Charente estuary, which extends for about 25 km. Temperature is the main factor controlling the hypoxia. This calls for the monitoring of small turbid macrotidal estuaries that are vulnerable to hypoxia, a risk expected to increase with global warming.
Simone R. Alin, Jan A. Newton, Richard A. Feely, Samantha Siedlecki, and Dana Greeley
Biogeosciences, 21, 1639–1673, https://doi.org/10.5194/bg-21-1639-2024, https://doi.org/10.5194/bg-21-1639-2024, 2024
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We provide a new multi-stressor data product that allows us to characterize the seasonality of temperature, O2, and CO2 in the southern Salish Sea and delivers insights into the impacts of major marine heatwave and precipitation anomalies on regional ocean acidification and hypoxia. We also describe the present-day frequencies of temperature, O2, and ocean acidification conditions that cross thresholds of sensitive regional species that are economically or ecologically important.
Pamela Linford, Iván Pérez-Santos, Paulina Montero, Patricio A. Díaz, Claudia Aracena, Elías Pinilla, Facundo Barrera, Manuel Castillo, Aida Alvera-Azcárate, Mónica Alvarado, Gabriel Soto, Cécile Pujol, Camila Schwerter, Sara Arenas-Uribe, Pilar Navarro, Guido Mancilla-Gutiérrez, Robinson Altamirano, Javiera San Martín, and Camila Soto-Riquelme
Biogeosciences, 21, 1433–1459, https://doi.org/10.5194/bg-21-1433-2024, https://doi.org/10.5194/bg-21-1433-2024, 2024
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The Patagonian fjords comprise a world region where low-oxygen water and hypoxia conditions are observed. An in situ dataset was used to quantify the mechanism involved in the presence of these conditions in northern Patagonian fjords. Water mass analysis confirmed the contribution of Equatorial Subsurface Water in the advection of the low-oxygen water, and hypoxic conditions occurred when the community respiration rate exceeded the gross primary production.
Ting Wang, Buyun Du, Inke Forbrich, Jun Zhou, Joshua Polen, Elsie M. Sunderland, Prentiss H. Balcom, Celia Chen, and Daniel Obrist
Biogeosciences, 21, 1461–1476, https://doi.org/10.5194/bg-21-1461-2024, https://doi.org/10.5194/bg-21-1461-2024, 2024
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The strong seasonal increases of Hg in aboveground biomass during the growing season and the lack of changes observed after senescence in this salt marsh ecosystem suggest physiologically controlled Hg uptake pathways. The Hg sources found in marsh aboveground tissues originate from a mix of sources, unlike terrestrial ecosystems, where atmospheric GEM is the main source. Belowground plant tissues mostly take up Hg from soils. Overall, the salt marsh currently serves as a small net Hg sink.
Eleanor Simpson, Debby Ianson, Karen E. Kohfeld, Ana C. Franco, Paul A. Covert, Marty Davelaar, and Yves Perreault
Biogeosciences, 21, 1323–1353, https://doi.org/10.5194/bg-21-1323-2024, https://doi.org/10.5194/bg-21-1323-2024, 2024
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Shellfish aquaculture operates in nearshore areas where data on ocean acidification parameters are limited. We show daily and seasonal variability in pH and saturation states of calcium carbonate at nearshore aquaculture sites in British Columbia, Canada, and determine the contributing drivers of this variability. We find that nearshore locations have greater variability than open waters and that the uptake of carbon by phytoplankton is the major driver of pH and saturation state variability.
S. Alejandra Castillo Cieza, Rachel H. R. Stanley, Pierre Marrec, Diana N. Fontaine, E. Taylor Crockford, Dennis J. McGillicuddy Jr., Arshia Mehta, Susanne Menden-Deuer, Emily E. Peacock, Tatiana A. Rynearson, Zoe O. Sandwith, Weifeng Zhang, and Heidi M. Sosik
Biogeosciences, 21, 1235–1257, https://doi.org/10.5194/bg-21-1235-2024, https://doi.org/10.5194/bg-21-1235-2024, 2024
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The coastal ocean in the northeastern USA provides many services, including fisheries and habitats for threatened species. In summer 2019, a bloom occurred of a large unusual phytoplankton, the diatom Hemiaulus, with nitrogen-fixing symbionts. This led to vast changes in productivity and grazing rates in the ecosystem. This work shows that the emergence of one species can have profound effects on ecosystem function. Such changes may become more prevalent as the ocean warms due to climate change.
Claudine Hauri, Brita Irving, Sam Dupont, Rémi Pagés, Donna D. W. Hauser, and Seth L. Danielson
Biogeosciences, 21, 1135–1159, https://doi.org/10.5194/bg-21-1135-2024, https://doi.org/10.5194/bg-21-1135-2024, 2024
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Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. We present pH and pCO2 time series (2016–2020) from the Chukchi Ecosystem Observatory and analyze the drivers of the current conditions to get a better understanding of how climate change and ocean acidification could affect the ecological niches of organisms.
William Hiles, Lucy C. Miller, Craig Smeaton, and William E. N. Austin
Biogeosciences, 21, 929–948, https://doi.org/10.5194/bg-21-929-2024, https://doi.org/10.5194/bg-21-929-2024, 2024
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Saltmarsh soils may help to limit the rate of climate change by storing carbon. To understand their impacts, they must be accurately mapped. We use drone data to estimate the size of three saltmarshes in NE Scotland. We find that drone imagery, combined with tidal data, can reliably inform our understanding of saltmarsh size. When compared with previous work using vegetation communities, we find that our most reliable new estimates of stored carbon are 15–20 % smaller than previously estimated.
De'Marcus Robinson, Anh L. D. Pham, David J. Yousavich, Felix Janssen, Frank Wenzhöfer, Eleanor C. Arrington, Kelsey M. Gosselin, Marco Sandoval-Belmar, Matthew Mar, David L. Valentine, Daniele Bianchi, and Tina Treude
Biogeosciences, 21, 773–788, https://doi.org/10.5194/bg-21-773-2024, https://doi.org/10.5194/bg-21-773-2024, 2024
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The present study suggests that high release of ferrous iron from the seafloor of the oxygen-deficient Santa Barabara Basin (California) supports surface primary productivity, creating positive feedback on seafloor iron release by enhancing low-oxygen conditions in the basin.
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhöfer, Felix Janssen, Na Liu, Jonathan Tarn, Franklin Kinnaman, David L. Valentine, and Tina Treude
Biogeosciences, 21, 789–809, https://doi.org/10.5194/bg-21-789-2024, https://doi.org/10.5194/bg-21-789-2024, 2024
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Declining oxygen (O2) concentrations in coastal oceans can threaten people’s ways of life and food supplies. Here, we investigate how mats of bacteria that proliferate on the seafloor of the Santa Barbara Basin sustain and potentially worsen these O2 depletion events through their unique chemoautotrophic metabolism. Our study shows how changes in seafloor microbiology and geochemistry brought on by declining O2 concentrations can help these mats grow as well as how that growth affects the basin.
Krysten Rutherford, Katja Fennel, Lina Garcia Suarez, and Jasmin G. John
Biogeosciences, 21, 301–314, https://doi.org/10.5194/bg-21-301-2024, https://doi.org/10.5194/bg-21-301-2024, 2024
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We downscaled two mid-century (~2075) ocean model projections to a high-resolution regional ocean model of the northwest North Atlantic (NA) shelf. In one projection, the NA shelf break current practically disappears; in the other it remains almost unchanged. This leads to a wide range of possible future shelf properties. More accurate projections of coastal circulation features would narrow the range of possible outcomes of biogeochemical projections for shelf regions.
Lennart Thomas Bach
Biogeosciences, 21, 261–277, https://doi.org/10.5194/bg-21-261-2024, https://doi.org/10.5194/bg-21-261-2024, 2024
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Ocean alkalinity enhancement (OAE) is a widely considered marine carbon dioxide removal method. OAE aims to accelerate chemical rock weathering, which is a natural process that slowly sequesters atmospheric carbon dioxide. This study shows that the addition of anthropogenic alkalinity via OAE can reduce the natural release of alkalinity and, therefore, reduce the efficiency of OAE for climate mitigation. However, the additionality problem could be mitigated via a variety of activities.
Tsuneo Ono, Daisuke Muraoka, Masahiro Hayashi, Makiko Yorifuji, Akihiro Dazai, Shigeyuki Omoto, Takehiro Tanaka, Tomohiro Okamura, Goh Onitsuka, Kenji Sudo, Masahiko Fujii, Ryuji Hamanoue, and Masahide Wakita
Biogeosciences, 21, 177–199, https://doi.org/10.5194/bg-21-177-2024, https://doi.org/10.5194/bg-21-177-2024, 2024
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We carried out parallel year-round observations of pH and related parameters in five stations around the Japan coast. It was found that short-term acidified situations with Omega_ar less than 1.5 occurred at four of five stations. Most of such short-term acidified events were related to the short-term low salinity event, and the extent of short-term pH drawdown at high freshwater input was positively correlated with the nutrient concentration of the main rivers that flow into the coastal area.
Cited articles
Adelson, J. M., Helz, G. R., and Miller, C. V.: Reconstructing the rise of recent coastal anoxia; molybdenum in Chesapeake Bay sediments, Geochim. Cosmochim. Ac., 65, 237–252, https://doi.org/10.1016/S0016-7037(00)00539-1, 2001.
Aksnes, D. L., Aure, J., Johansen, P. O., Johnsen, G. H., and Salvanes, A. G. V.: Multi-decadal warming of Atlantic water and associated decline of dissolved oxygen in a deep fjord, Estuar. Coast. Shelf. S., 228, 106392, https://doi.org/10.1016/j.ecss.2019.106392, 2019.
Alessi, D. S., Lezama-Pacheco, J. S., Stubbs, J. E., Janousch, M., Bargar, J. R., Persson, P., and Bernier-Latmani, R.: The product of microbial uranium reduction includes multiple species with U(IV)-phosphate coordination, Geochim. Cosmochim. Ac., 131, 115–127, https://doi.org/10.1016/j.gca.2014.01.005, 2014.
Alessi, D. S., Uster, B., Veeramani, H., Suvorova, E. I., Lezama-Pacheco, J. S., Stubbs, J. E., Bargar, J. R., and Bernier-Latmani, R.: Quantitative separation of monomeric U(IV) from UO2 in products of U(VI) reduction, Environ. Sci. Technol., 46, 6150–6157, https://doi.org/10.1021/es204123z, 2012.
Algeo, T. J. and Li, C.: Redox classification and calibration of redox thresholds in sedimentary systems, Geochim. Cosmochim. Ac., 287, 8–26, https://doi.org/10.1016/j.gca.2020.01.055, 2020.
Algeo, T. J. and Lyons, T. W.: Mo-total organic carbon covariation in modern anoxic marine environments: Implications for analysis of paleoredox and paleohydrographic conditions, Paleoceanography, 21, PA1016, https://doi.org/10.1029/2004pa001112, 2006.
Algeo, T. J. and Maynard, J. B.: Trace-element behavior and redox facies in core shales of Upper Pennsylvanian Kansas-type cyclothems, Chem. Geol., 206, 289–318, https://doi.org/10.1016/j.chemgeo.2003.12.009, 2004.
Algeo, T. J. and Tribovillard, N.: Environmental analysis of paleoceanographic systems based on molybdenum–uranium covariation, Chem. Geol., 268, 211–225, https://doi.org/10.1016/j.chemgeo.2009.09.001, 2009.
Aller, R. C.: Bioturbation and Remineralization of Sedimentary Organic-Matter – Effects of Redox Oscillation, Chem. Geol., 114, 331–345, https://doi.org/10.1016/0009-2541(94)90062-0, 1994.
Anderson, R., LeHuray, A., Fleisher, M., and Murray, J.: Uranium deposition in saanich inlet sediments, vancouver island, Geochim. Cosmochim. Ac., 53, 2205–2213, https://doi.org/10.1016/0016-7037(89)90344-X, 1989.
Arneborg, L.: Turnover times for the water above sill level in Gullmar Fjord, Cont. Shelf Res., 24, 443–460, https://doi.org/10.1016/j.csr.2003.12.005, 2004.
Bachmaf, S. and Merkel, B. J.: Sorption of uranium(VI) at the clay mineral-water interface, Environ. Earth. Sci., 63, 925–934, https://doi.org/10.1007/s12665-010-0761-6, 2011.
Bargar, J. R., Bernier-Latmani, R., Giammar, D. E., and Tebo, B. M.: Biogenic Uraninite Nanoparticles and Their Importance for Uranium Remediation, Elements, 4, 407–412, https://doi.org/10.2113/gselements.4.6.407, 2008.
Bargar, J. R., Williams, K. H., Campbell, K. M., Long, P. E., Stubbs, J. E., Suvorova, E. I., Lezama-Pacheco, J. S., Alessi, D. S., Stylo, M., Webb, S. M., Davis, J. A., Giammar, D. E., Blue, L. Y., and Bernier-Latmani, R.: Uranium redox transition pathways in acetate-amended sediments, P. Natl. Acad. Sci. USA, 110, 4506–4511, https://doi.org/10.1073/pnas.1219198110, 2013.
Barnes, C. E. and Cochran, J. K.: Geochemistry of uranium in Black Sea sediments, Deep-Sea Res. Pt. A, 38, S1237–S1254, https://doi.org/10.1016/s0198-0149(10)80032-9, 1991.
Bennett, W. W. and Canfield, D. E.: Redox-sensitive trace metals as paleoredox proxies: A review and analysis of data from modern sediments, Earth Sci. Rev., 204, 103175, https://doi.org/10.1016/j.earscirev.2020.103175, 2020.
Berner, R. A.: Early diagenesis: a theoretical approach, 1, Princeton University Press, https://doi.org/10.2307/j.ctvx8b6p2, 1980.
Bernier-Latmani, R., Veeramani, H., Vecchia, E. D., Junier, P., Lezama-Pacheco, J. S., Suvorova, E. I., Sharp, J. O., Wigginton, N. S., and Bargar, J. R.: Non-uraninite Products of Microbial U(VI) Reduction, Environ. Sci. Technol., 44, 9456–9462, https://doi.org/10.1021/es101675a, 2010.
Berrang, P. and Grill, E.: The effect of manganese oxide scavenging on molybdenum in Saanich Inlet, British Columbia, Mar. Chem., 2, 125–148, https://doi.org/10.1016/0304-4203(74)90033-4, 1974.
Bertine, K. K. and Turekian, K. K.: Molybdenum in Marine Deposits, Geochim. Cosmochim. Ac., 37, 1415–1434, https://doi.org/10.1016/0016-7037(73)90080-X, 1973.
Bhattacharyya, A., Campbell, K. M., Kelly, S. D., Roebbert, Y., Weyer, S., Bernier-Latmani, R., and Borch, T.: Biogenic non-crystalline U((IV)) revealed as major component in uranium ore deposits, Nat. Commun., 8, 15538, https://doi.org/10.1038/ncomms15538, 2017.
Bi, Y. Q. and Hayes, K. F.: Nano-FeS Inhibits UO2 Reoxidation under Varied Oxic Conditions, Environ. Sci. Technol., 48, 632–640, https://doi.org/10.1021/es4043353, 2014.
Bianchi, T. S., Arndt, S., Austin, W. E. N., Benn, D. I., Bertrand, S., Cui, X. Q., Faust, J. C., Koziorowska-Makuch, K., Moy, C. M., Savage, C., Smeaton, C., Smith, R. W., and Syvitski, J.: Fjords as Aquatic Critical Zones (ACZs), Earth Sci. Rev., 203, 103145, https://doi.org/10.1016/j.earscirev.2020.103145, 2020.
Björk, G. and Nordberg, K.: Upwelling along the Swedish west coast during the 20th century, Cont. Shelf Res., 23, 1143–1159, https://doi.org/10.1016/S0278-4343(03)00081-5, 2003.
Björk, G., Liungman, O., and Rydberg, L.: Net circulation and salinity variations in an open-ended Swedish Fjord System, Estuaries, 23, 367–380, https://doi.org/10.2307/1353329, 2000.
Boesen, C. and Postma, D.: Pyrite Formation in Anoxic Environments of the Baltic, Am. J. Sci., 288, 575–603, https://doi.org/10.2475/ajs.288.6.575, 1988.
Bonatti, E., Fisher, D., Joensuu, O., and Rydell, H.: Postdepositional mobility of some transition elements, phosphorus, uranium and thorium in deep sea sediments, Geochim. Cosmochim. Ac., 35, 189–201, https://doi.org/10.1016/0016-7037(71)90057-3, 1971.
Bone, S. E., Dynes, J. J., Cliff, J., and Bargar, J. R.: Uranium(IV) adsorption by natural organic matter in anoxic sediments, Proc. Natl. Acad. Sci. USA, 114, 711–716, https://doi.org/10.1073/pnas.1611918114, 2017.
Boone, W., Rysgaard, S., Carlson, D. F., Meire, L., Kirillov, S., Mortensen, J., Dmitrenko, I., Vergeynst, L., and Sejr, M. K.: Coastal Freshening Prevents Fjord Bottom Water Renewal in Northeast Greenland: A Mooring Study From 2003 to 2015, Geophys. Res. Lett., 45, 2726–2733, https://doi.org/10.1002/2017gl076591, 2018.
Bordovskiy, O. K.: Sources of organic matter in marine basins, Mar. Geol., 3, 5–31, https://doi.org/10.1016/0025-3227(65)90003-4, 1965.
Boudreau, B. P.: Diagenetic models and their implementation, Springer, Berlin Heidelberg, ISBN-13: 978-3-642-64399-6, 1997.
Boyanov, M. I., Fletcher, K. E., Kwon, M. J., Rui, X., O'Loughlin, E. J., Loffler, F. E., and Kemner, K. M.: Solution and Microbial Controls on the Formation of Reduced U(IV) Species, Environ. Sci. Technol., 45, 8336–8344, https://doi.org/10.1021/es2014049, 2011.
Boyd, P. W. and Ellwood, M. J.: The biogeochemical cycle of iron in the ocean, Nat. Geosci., 3, 675–682, https://doi.org/10.1038/ngeo964, 2010.
Breitburg, D., Levin, L. A., Oschlies, A., Gregoire, M., Chavez, F. P., Conley, D. J., Garcon, V., Gilbert, D., Gutierrez, D., Isensee, K., Jacinto, G. S., Limburg, K. E., Montes, I., Naqvi, S. W. A., Pitcher, G. C., Rabalais, N. N., Roman, M. R., Rose, K. A., Seibel, B. A., Telszewski, M., Yasuhara, M., and Zhang, J.: Declining oxygen in the global ocean and coastal waters, Science, 359, eaam7240, https://doi.org/10.1126/science.aam7240, 2018.
Brennecka, G. A., Wasylenki, L. E., Bargar, J. R., Weyer, S., and Anbar, A. D.: Uranium Isotope Fractionation during Adsorption to Mn-Oxyhydroxides, Environ. Sci. Technol., 45, 1370–1375, https://doi.org/10.1021/es103061v, 2011.
Brewer, P. G. and Spencer, D. W.: Colorimetric Determination of Manganese in Anoxic Waters, Limnol. Oceanogr., 16, 107–110, https://doi.org/10.4319/lo.1971.16.1.0107, 1971.
Brinkmann, I., Barras, C., Jilbert, T., Næraa, T., Paul, K. M., Schweizer, M., and Filipsson, H. L.: Drought recorded by Ba/Ca in coastal benthic foraminifera, Biogeosciences, 19, 2523–2535, https://doi.org/10.5194/bg-19-2523-2022, 2022.
Brinkmann, I., Schweizer, M., Singer, D., Quinchard, S., Barras, C., Bernhard, J. M., and Filipsson, H. L.: Through the eDNA looking glass: Responses of fjord benthic foraminiferal communities to contrasting environmental conditions, J. Eukaryot. Microbiol., 70, e12975, https://doi.org/10.1111/jeu.12975, 2023a.
Brinkmann, I., Barras, C., Jilbert, T., Paul, K. M., Somogyi, A., Ni, S., Schweizer, M., Bernhard, J. M., and Filipsson, H. L.: Benthic Foraminiferal
Brumsack, H.-J.: The trace metal content of recent organic carbon-rich sediments: Implications for Cretaceous black shale formation, Palaeogeogr. Palaeocl., 232, 344–361, https://doi.org/10.1016/j.palaeo.2005.05.011, 2006.
Burdige, D. J.: The Biogeochemistry of Manganese and Iron Reduction in Marine-Sediments, Earth Sci. Rev., 35, 249–284, https://doi.org/10.1016/0012-8252(93)90040-E, 1993.
Burdige, D. J.: Geochemistry of Marine Sediments, Princeton University Press, https://doi.org/10.2307/j.ctv131bw7s, 2006.
Burton, E. D., Sullivan, L. A., Bush, R. T., Johnston, S. G., and Keene, A. F.: A simple and inexpensive chromium-reducible sulfur method for acid-sulfate soils, Appl. Geochem., 23, 2759–2766, https://doi.org/10.1016/j.apgeochem.2008.07.007, 2008.
Calvert, S. E. and Pedersen, T. F.: Sedimentary geochemistry of manganese: Implications for the environment of formation of manganiferous black shales, Econ. Geol. Bull. Soc., 91, 36–47, https://doi.org/10.2113/gsecongeo.91.1.36, 1996.
Calvert, S. E., Piper, D. Z., Thunell, R. C., and Astor, Y.: Elemental settling and burial fluxes in the Cariaco Basin, Mar. Chem., 177, 607–629, https://doi.org/10.1016/j.marchem.2015.10.001, 2015.
Canfield, D. E., Thamdrup, B., and Hansen, J. W.: The anaerobic degradation of organic matter in Danish coastal sediments: Iron reduction, manganese reduction, and sulfate reduction, Geochim. Cosmochim. Ac., 57, 3867–3883, https://doi.org/10.1016/0016-7037(93)90340-3, 1993.
Carman, R. and Rahm, L.: Early diagenesis and chemical characteristics of interstitial water and sediments in the deep deposition bottoms of the Baltic proper, J. Sea Res., 37, 25–47, https://doi.org/10.1016/S1385-1101(96)00003-2, 1997.
Chappaz, A., Lyons, T. W., Gregory, D. D., Reinhard, C. T., Gill, B. C., Li, C., and Large, R. R.: Does pyrite act as an important host for molybdenum in modern and ancient euxinic sediments?, Geochim. Cosmochim. Ac., 126, 112–122, https://doi.org/10.1016/j.gca.2013.10.028, 2014.
Chen, D. L. and Hellstrom, C.: The influence of the North Atlantic Oscillation on the regional temperature variability in Sweden: spatial and temporal variations, Tellus A, 51, 505–516, https://doi.org/10.1034/j.1600-0870.1999.t01-4-00004.x, 1999.
Choppin, G. R. and Jensen, M. P.: Actinides in Solution: Complexation and Kinetics, in: The Chemistry of the Actinide and Transactinide Elements, edited by: Morss, L. R., Edelstein, N. M., and Fuger, J., Springer Netherlands, Dordrecht, 2524–2621, https://doi.org/10.1007/1-4020-3598-5_23, 2006.
Claff, S. R., Sullivan, L. A., Burton, E. D., and Bush, R. T.: A sequential extraction procedure for acid sulfate soils: partitioning of iron, Geoderma, 155, 224–230, https://doi.org/10.1016/j.geoderma.2009.12.002, 2010.
Cochran, J. K., Carey, A. E., Sholkovitz, E. R., and Surprenant, L. D.: The Geochemistry of Uranium and Thorium in Coastal Marine-Sediments and Sediment Pore Waters, Geochim. Cosmochim. Ac., 50, 663–680, https://doi.org/10.1016/0016-7037(86)90344-3, 1986.
Conley, D. J., Carstensen, J., Aigars, J., Axe, P., Bonsdorff, E., Eremina, T., Haahti, B. M., Humborg, C., Jonsson, P., Kotta, J., Lannegren, C., Larsson, U., Maximov, A., Medina, M. R., Lysiak-Pastuszak, E., Remeikaite-Nikiene, N., Walve, J., Wilhelms, S., and Zillen, L.: Hypoxia is increasing in the coastal zone of the Baltic Sea, Environ. Sci. Technol., 45, 6777–6783, https://doi.org/10.1021/es201212r, 2011.
Cornwell, J. C. and Morse, J. W.: The characterization of iron sulfide minerals in anoxic marine sediments, Mar. Chem., 22, 193–206, https://doi.org/10.1016/0304-4203(87)90008-9, 1987.
Crusius, J., Calvert, S., Pedersen, T., and Sage, D.: Rhenium and molybdenum enrichments in sediments as indicators of oxic, suboxic and sulfidic conditions of deposition, Earth Planet. Sc. Lett., 145, 65–78, https://doi.org/10.1016/S0012-821x(96)00204-X, 1996.
Cumberland, S. A., Evans, K., Douglas, G., de Jonge, M., Fisher, L., Howard, D., and Moreau, J. W.: Characterisation of uranium-pyrite associations within organic-rich Eocene sediments using EM, XFM-µXANES and µXRD, Ore. Geol. Rev., 133, 104051, https://doi.org/10.1016/j.oregeorev.2021.104051, 2021.
Cumberland, S. A., Etschmann, B., Brugger, J., Douglas, G., Evans, K., Fisher, L., Kappen, P., and Moreau, J. W.: Characterization of uranium redox state in organic-rich Eocene sediments, Chemosphere, 194, 602–613, https://doi.org/10.1016/j.chemosphere.2017.12.012, 2018.
Dahl, T. W., Chappaz, A., Hoek, J., McKenzie, C. J., Svane, S., and Canfield, D. E.: Evidence of molybdenum association with particulate organic matter under sulfidic conditions, Geobiology, 15, 311–323, https://doi.org/10.1111/gbi.12220, 2017.
Dang, D. H., Novotnik, B., Wang, W., Georg, R. B., and Evans, R. D.: Uranium Isotope Fractionation during Adsorption, (Co)precipitation, and Biotic Reduction, Environ. Sci. Technol., 50, 12695–12704, https://doi.org/10.1021/acs.est.6b01459, 2016.
Darelius, E.: On the effect of climate trends in coastal density on deep water renewal frequency in sill fjords-A statistical approach, Estuar. Coast. Shelf. S., 243, 106904, https://doi.org/10.1016/j.ecss.2020.106904, 2020.
Dellwig, O., Wegwerth, A., and Arz, H. W.: Anatomy of the Major Baltic Inflow in 2014: Impact of manganese and iron shuttling on phosphorus and trace metals in the Gotland Basin, Baltic Sea, Cont. Shelf Res., 223, 104449, https://doi.org/10.1016/j.csr.2021.104449, 2021.
Dellwig, O., Schnetger, B., Meyer, D., Pollehne, F., Häusler, K., and Arz, H. W.: Impact of the Major Baltic Inflow in 2014 on Manganese Cycling in the Gotland Deep (Baltic Sea), Front. Mar. Sci., 5, 248, https://doi.org/10.3389/fmars.2018.00248, 2018.
Egger, M., Lenstra, W., Jong, D., Meysman, F. J., Sapart, C. J., van der Veen, C., Rockmann, T., Gonzalez, S., and Slomp, C. P.: Rapid Sediment Accumulation Results in High Methane Effluxes from Coastal Sediments, PLoS One, 11, e0161609, https://doi.org/10.1371/journal.pone.0161609, 2016.
Engström, P., Dalsgaard, T., Hulth, S., and Aller, R. C.: Anaerobic ammonium oxidation by nitrite (anammox): Implications for N-2 production in coastal marine sediments, Geochim. Cosmochim. Ac., 69, 2057–2065, https://doi.org/10.1016/j.gca.2004.09.032, 2005.
Erickson, B. E. and Helz, G. R.: Molybdenum(VI) speciation in sulfidic waters: Stability and lability of thiomolybdates, Geochim. Cosmochim. Ac., 64, 1149–1158, https://doi.org/10.1016/S0016-7037(99)00423-8, 2000.
Faust, J. C. and Knies, J.: Organic Matter Sources in North Atlantic Fjord Sediments, Geochem. Geophy. Geosy., 20, 2872–2885, https://doi.org/10.1029/2019gc008382, 2019.
Filipsson, H. L. and Nordberg, K.: A 200-year environmental record of a low-oxygen fjord, Sweden, elucidated by benthic foraminifera, sediment characteristics and hydrographic data, J. Foramin. Res., 34, 277–293, https://doi.org/10.2113/34.4.277, 2004a.
Filipsson, H. L. and Nordberg, K.: Climate variations, an overlooked factor influencing the recent marine environment. An example from Gullmar Fjord, Sweden, illustrated by benthic foraminifera and hydrographic data, Estuaries, 27, 867–881, https://doi.org/10.1007/Bf02912048, 2004b.
Filipsson, H. L., Bjork, G., Harland, R., McQuoid, M. R., and Nordberg, K.: A major change in the phytoplankton of a Swedish sill fjord – A consequence of engineering work?, Estuar. Coast. Shelf. S., 63, 551–560, https://doi.org/10.1016/j.ecss.2005.01.001, 2005.
Fletcher, K. E., Boyanov, M. I., Thomas, S. H., Wu, Q. Z., Kemner, K. M., and Loffler, F. E.: U(VI) Reduction to Mononuclear U(IV) by Desulfitobacterium Species, Environ. Sci. Technol., 44, 4705–4709, https://doi.org/10.1021/es903636c, 2010.
Fredrickson, J. K., Zachara, J. M., Kennedy, D. W., Duff, M. C., Gorby, Y. A., Li, S. M. W., and Krupka, K. M.: Reduction of U(VI) in goethite (alpha-FeOOH) suspensions by a dissimilatory metal-reducing bacterium, Geochim. Cosmochim. Ac., 64, 3085–3098, https://doi.org/10.1016/S0016-7037(00)00397-5, 2000.
Fu, H. Y., Zhang, H., Sui, Y., Hu, N., Ding, D. X., Ye, Y. J., Li, G. Y., Wang, Y. D., and Dai, Z. R.: Transformation of uranium species in soil during redox oscillations, Chemosphere, 208, 846–853, https://doi.org/10.1016/j.chemosphere.2018.06.059, 2018.
Fuller, A. J., Leary, P., Gray, N. D., Davies, H. S., Mosselmans, J. F. W., Cox, F., Robinson, C. H., Pittman, J. K., McCann, C. M., Muir, M., Graham, M. C., Utsunomiya, S., Bower, W. R., Morris, K., Shaw, S., Bots, P., Livens, F. R., and Law, G. T. W.: Organic complexation of U(VI) in reducing soils at a natural analogue site: Implications for uranium transport, Chemosphere, 254, 126859, https://doi.org/10.1016/j.chemosphere.2020.126859, 2020.
Ginder-Vogel, M. and Fendorf, S.: Biogeochemical Uranium Redox Transformations: Potential Oxidants of Uraninite, in: Developments in Earth and Environmental Sciences, edited by: Barnett, M. O. and Kent, D. B., Elsevier, 293–319, https://doi.org/10.1016/S1571-9197(07)07011-5, 2008.
Ginder-Vogel, M., Criddle, C. S., and Fendorf, S.: Thermodynamic constraints on the oxidation of biogenic UO2 by Fe(III) (hydr) oxides, Environ. Sci. Technol., 40, 3544–3550, https://doi.org/10.1021/es052305p, 2006.
Glud, R. N., Gundersen, J. K., Roy, H., and Jorgensen, B. B.: Seasonal dynamics of benthic O2 uptake in a semienclosed bay: Importance of diffusion and faunal activity, Limnol. Oceanogr., 48, 1265–1276, https://doi.org/10.4319/lo.2003.48.3.1265, 2003.
Goldberg, T., Archer, C., Vance, D., Thamdrup, B., McAnena, A., and Poulton, S. W.: Controls on Mo isotope fractionations in a Mn-rich anoxic marine sediment, Gullmar Fjord, Sweden, Chem. Geol., 296, 73–82, https://doi.org/10.1016/j.chemgeo.2011.12.020, 2012.
Goñi, M. A., Teixeira, M. J., and Perkey, D. W.: Sources and distribution of organic matter in a river-dominated estuary (Winyah Bay, SC, USA), Estuar. Coast. Shelf. S., 57, 1023–1048, https://doi.org/10.1016/S0272-7714(03)00008-8, 2003.
Gustafsson, M. and Nordberg, K.: Benthic foraminifera and their response to hydrography, periodic hypoxic conditions and primary production in the Koljo fjord on the Swedish west coast, J. Sea Res., 41, 163–178, https://doi.org/10.1016/S1385-1101(99)00002-7, 1999.
Harland, R., Nordberg, K., and Filipsson, H. L.: The seasonal occurrence of dinoflagellate cysts in surface sediments from Koljö Fjord, west coast of Sweden – a note, Rev. Palaeobot. Palyno., 128, 107–117, https://doi.org/10.1016/S0034-6667(03)00115-5, 2004.
Harland, R., Nordberg, K., and Filipsson, H. L.: Dinoflagellate cysts and hydrographical change in Gullmar Fjord, west coast of Sweden, Sci. Total. Environ., 355, 204–231, https://doi.org/10.1016/j.scitotenv.2005.02.030, 2006.
Hassellöv, M., Lyven, B., Bengtsson, H., Jansen, R., Turner, D. R., and Beckett, R.: Particle size distributions of clay-rich sediments and pure clay minerals: A comparison of grain size analysis with sedimentation field-flow fractionation, Aquat. Geochem., 7, 155–171, https://doi.org/10.1023/A:1017905822612, 2001.
Helz, G., Miller, C., Charnock, J., Mosselmans, J., Pattrick, R., Garner, C., and Vaughan, D.: Mechanism of molybdenum removal from the sea and its concentration in black shales: EXAFS evidence, Geochim. Cosmochim. Ac., 60, 3631–3642, https://doi.org/10.1016/0016-7037(96)00195-0, 1996.
Helz, G. R.: Dissolved molybdenum asymptotes in sulfidic waters, Geochem. Perspect. Lett., 19, 23–26, https://doi.org/10.7185/geochemlet.2129, 2021.
Helz, G. R. and Vorlicek, T. P.: Precipitation of molybdenum from euxinic waters and the role of organic matter, Chem. Geol., 509, 178–193, https://doi.org/10.1016/j.chemgeo.2019.02.001, 2019.
Hermans, M., Pascual, M. A., Behrends, T., Lenstra, W. K., Conley, D. J., and Slomp, C. P.: Coupled dynamics of iron, manganese, and phosphorus in brackish coastal sediments populated by cable bacteria, Limnol. Oceanogr., 66, 2611–2631, https://doi.org/10.1002/lno.11776, 2021.
Hermans, M., Lenstra, W. K., Hidalgo-Martinez, S., van Helmond, N. A. G. M., Witbaard, R., Meysman, F. J. R., Gonzalez, S., and Slomp, C. P.: Abundance and Biogeochemical Impact of Cable Bacteria in Baltic Sea Sediments, Environ. Sci. Technol., 53, 7494–7503, https://doi.org/10.1021/acs.est.9b01665, 2019a.
Hermans, M., Lenstra, W. K., van Helmond, N. A. G. M., Behrends, T., Egger, M., Séguret, M. J. M., Gustafsson, E., Gustafsson, B. G., and Slomp, C. P.: Impact of natural re-oxygenation on the sediment dynamics of manganese, iron and phosphorus in a euxinic Baltic Sea basin, Geochim. Cosmochim. Ac., 246, 174–196, https://doi.org/10.1016/j.gca.2018.11.033, 2019b.
Hirose, K. and Sugimura, Y.: Chemical Speciation of Particulate Uranium in Seawater, J. Radioanal. Nucl. Chem., 149, 83–96, https://doi.org/10.1007/Bf02053716, 1991.
Hjorth, T.: Effects of freeze-drying on partitioning patterns of major elements and trace metals in lake sediments, Anal. Chim. Acta., 526, 95–102, https://doi.org/10.1016/j.aca.2004.08.007, 2004.
Howe, J. A., Austin, W. E. N., Forwick, M., Paetzel, M., Harland, R., and Cage, A. G.: Fjord systems and archives: a review, Geol. Soc. Lond. Spec. Publ., 344, 5–15, https://doi.org/10.1144/sp344.2, 2010.
Huang, G. X., Chen, Z. Y., Sun, J. C., Liu, F., Wang, J., and Zhang, Y.: Effect of sample pretreatment on the fractionation of arsenic in anoxic soils, Environ. Sci. Pollut. R., 22, 8367–8374, https://doi.org/10.1007/s11356-014-3958-5, 2015.
Huckriede, H. and Meischner, D.: Origin and environment of manganese-rich sediments within black-shale basins, Geochim. Cosmochim. Ac., 60, 1399–1413, https://doi.org/10.1016/0016-7037(96)00008-7, 1996.
Huerta-Diaz, M. A. and Morse, J. W.: Pyritization of Trace-Metals in Anoxic Marine-Sediments, Geochim. Cosmochim. Ac., 56, 2681–2702, https://doi.org/10.1016/0016-7037(92)90353-K, 1992.
Hurrell, J. W.: Decadal Trends in the North-Atlantic Oscillation - Regional Temperatures and Precipitation, Science, 269, 676–679, https://doi.org/10.1126/science.269.5224.676, 1995.
Jilbert, T. and Slomp, C. P.: Iron and manganese shuttles control the formation of authigenic phosphorus minerals in the euxinic basins of the Baltic Sea, Geochim. Cosmochim. Ac., 107, 155–169, https://doi.org/10.1016/j.gca.2013.01.005, 2013.
Jilbert, T., Asmala, E., Schröder, C., Tiihonen, R., Myllykangas, J.-P., Virtasalo, J. J., Kotilainen, A., Peltola, P., Ekholm, P., and Hietanen, S.: Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments, Biogeosciences, 15, 1243–1271, https://doi.org/10.5194/bg-15-1243-2018, 2018.
Jokinen, S. A., Jilbert, T., Tiihonen-Filppula, R., and Koho, K.: Terrestrial organic matter input drives sedimentary trace metal sequestration in a human-impacted boreal estuary, Sci. Total Environ., 717, 137047, https://doi.org/10.1016/j.scitotenv.2020.137047, 2020a.
Jokinen, S. A., Koho, K., Virtasalo, J. J., and Jilbert, T.: Depth and intensity of the sulfate-methane transition zone control sedimentary molybdenum and uranium sequestration in a eutrophic low-salinity setting, Appl. Geochem., 122, 104767, https://doi.org/10.1016/j.apgeochem.2020.104767, 2020b.
Kersten, M. and Förstner, U.: Chemical Fractionation of Heavy-Metals in Anoxic Estuarine and Coastal Sediments, Water. Sci. Technol., 18, 121–130, https://doi.org/10.2166/wst.1986.0187, 1986.
Klinkhammer, G. P. and Palmer, M. R.: Uranium in the Oceans - Where It Goes and Why, Geochim. Cosmochim. Ac., 55, 1799–1806, https://doi.org/10.1016/0016-7037(91)90024-Y, 1991.
Kotov, S. and Paelike, H.: QAnalySeries-a cross-platform time series tuning and analysis tool, AGU Fall Meeting Abstracts, PP53D-1230, https://doi.org/10.1002/essoar.10500226.1, 2018.
Kraal, P., Slomp, C. P., Forster, A., Kuypers, M. M. M., and Sluijs, A.: Pyrite oxidation during sample storage determines phosphorus fractionation in carbonate-poor anoxic sediments, Geochim. Cosmochim. Ac., 73, 3277–3290, https://doi.org/10.1016/j.gca.2009.02.026, 2009.
Lalonde, K., Mucci, A., Ouellet, A., and Gélinas, Y.: Preservation of organic matter in sediments promoted by iron, Nature, 483, 198–200, https://doi.org/10.1038/nature10855, 2012.
Lamb, A. L., Wilson, G. P., and Leng, M. J.: A review of coastal palaeoclimate and relative sea-level reconstructions using delta C-13 and C/N ratios in organic material, Earth Sci. Rev., 75, 29–57, https://doi.org/10.1016/j.earscirev.2005.10.003, 2006.
Langmuir, D.: Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits, Geochim. Cosmochim. Ac., 42, 547–569, 1978.
Lee, S. Y., Baik, M. H., and Choi, J. W.: Biogenic Formation and Growth of Uraninite (UO2), Environ. Sci. Technol., 44, 8409–8414, https://doi.org/10.1021/es101905m, 2010.
Lenstra, W., Klomp, R., Molema, F., Behrends, T., and Slomp, C.: A sequential extraction procedure for particulate manganese and its application to coastal marine sediments, Chem. Geol., 584, 120538, https://doi.org/10.1016/j.chemgeo.2021.120538, 2021a.
Lenstra, W. K., Hermans, M., Seguret, M. J. M., Witbaard, R., Severmann, S., Behrends, T., and Slomp, C. P.: Coastal hypoxia and eutrophication as key controls on benthic release and water column dynamics of iron and manganese, Limnol. Oceanogr., 66, 807–826, https://doi.org/10.1002/lno.11644, 2021b.
Lenstra, W. K., Seguret, M. J. M., Behrends, T., Groeneveld, R. K., Hermans, M., Witbaard, R., and Slomp, C. P.: Controls on the shuttling of manganese over the northwestern Black Sea shelf and its fate in the euxinic deep basin, Geochim. Cosmochim. Ac., 273, 177–204, https://doi.org/10.1016/j.gca.2020.01.031, 2020.
Lenstra, W. K., Hermans, M., Séguret, M. J. M., Witbaard, R., Behrends, T., Dijkstra, N., van Helmond, N. A. G. M., Kraal, P., Laan, P., Rijkenberg, M. J. A., Severmann, S., Teaca, A., and Slomp, C. P.: The shelf-to-basin iron shuttle in the Black Sea revisited, Chem. Geol., 511, 314–341, https://doi.org/10.1016/j.chemgeo.2018.10.024, 2019.
Lenz, C., Jilbert, T., Conley, D. J., and Slomp, C. P.: Hypoxia-driven variations in iron and manganese shuttling in the Baltic Sea over the past 8 kyr, Geochem. Geophy. Geosy., 16, 3754–3766, https://doi.org/10.1002/2015gc005960, 2015a.
Lenz, C., Jilbert, T., Conley, D. J., Wolthers, M., and Slomp, C. P.: Are recent changes in sediment manganese sequestration in the euxinic basins of the Baltic Sea linked to the expansion of hypoxia?, Biogeosciences, 12, 4875–4894, https://doi.org/10.5194/bg-12-4875-2015, 2015b.
Li, Y. H. and Gregory, S.: Diffusion of Ions in Sea-Water and in Deep-Sea Sediments, Geochim. Cosmochim. Ac., 38, 703–714, https://doi.org/10.1016/0016-7037(74)90145-8, 1974.
Lindahl, O. and Hernroth, L.: Large-Scale and Long-Term Variations in the Zooplankton Community of the Gullmar Fjord, Sweden, in Relation to Advective Processes, Mar. Ecol. Prog. Ser., 43, 161–171, https://doi.org/10.3354/meps043161, 1988.
Liu, J. and Algeo, T. J.: Beyond redox: Control of trace-metal enrichment in anoxic marine facies by watermass chemistry and sedimentation rate, Geochim. Cosmochim. Ac., 287, 296–317, https://doi.org/10.1016/j.gca.2020.02.037, 2020.
Lohan, M. C. and Bruland, K. W.: Elevated Fe(II) and dissolved Fe in hypoxic shelf waters off Oregon and Washington: An enhanced source of iron to coastal upwelling regimes, Environ. Sci. Technol., 42, 6462–6468, https://doi.org/10.1021/es800144j, 2008.
Lovley, D. R., Phillips, E. J. P., Gorby, Y. A., and Landa, E. R.: Microbial Reduction of Uranium, Nature, 350, 413–416, https://doi.org/10.1038/350413a0, 1991.
Lovley, D. R., Roden, E. E., Phillips, E. J. P., and Woodward, J. C.: Enzymatic Iron and Uranium Reduction by Sulfate-Reducing Bacteria, Mar. Geol., 113, 41–53, https://doi.org/10.1016/0025-3227(93)90148-O, 1993.
Lyons, T. W., Werne, J. P., Hollander, D. J., and Murray, R. W.: Contrasting sulfur geochemistry and Fe/Al and Mo/Al ratios across the last oxic-to-anoxic transition in the Cariaco Basin, Venezuela, Chem. Geol., 195, 131–157, https://doi.org/10.1016/s0009-2541(02)00392-3, 2003.
Madison, A. S., Tebo, B. M., Mucci, A., Sundby, B., and Luther, G. W.: Abundant Porewater Mn(III) Is a Major Component of the Sedimentary Redox System, Science, 341, 875–878, https://doi.org/10.1126/science.1241396, 2013.
McKee, B. A., Demaster, D. J., and Nittrouer, C. A.: Uranium Geochemistry on the Amazon Shelf – Evidence for Uranium Release from Bottom Sediments, Geochim. Cosmochim. Ac., 51, 2779–2786, https://doi.org/10.1016/0016-7037(87)90157-8, 1987.
McManus, J., Berelson, W. M., Klinkhammer, G. P., Hammond, D. E., and Holm, C.: Authigenic uranium: Relationship to oxygen penetration depth and organic carbon rain, Geochim. Cosmochim. Ac., 69, 95–108, https://doi.org/10.1016/j.gca.2004.06.023, 2005.
McQuoid, M. R. and Nordberg, K.: Environmental influence on the diatom and silicoflagellate assemblages in Koljo Fjord (Sweden) over the last two centuries, Estuaries, 26, 927–937, https://doi.org/10.1007/Bf02803351, 2003.
Mei, H. Y., Aoyagi, N., Saito, T., Kozai, N., Sugiura, Y., and Tachi, Y.: Uranium (VI) sorption on illite under varying carbonate concentrations: Batch experiments, modeling, and cryogenic time-resolved laser fluorescence spectroscopy study, Appl. Geochem., 136, 105178, https://doi.org/10.1016/j.apgeochem.2021.105178, 2022.
Meier, H. E. M., Kniebusch, M., Dieterich, C., Groger, M., Zorita, E., Elmgren, R., Myrberg, K., Ahola, M. P., Bartosova, A., Bonsdorff, E., Borgel, F., Capell, R., Carlen, I., Carlund, T., Carstensen, J., Christensen, O. B., Dierschke, V., Frauen, C., Frederiksen, M., Gaget, E., Galatius, A., Haapala, J. J., Halkka, A., Hugelius, G., Hunicke, B., Jaagus, J., Jussi, M., Kayhko, J., Kirchner, N., Kjellstrom, E., Kulinski, K., Lehmann, A., Lindstrom, G., May, W., Miller, P. A., Mohrholz, V., Muller-Karulis, B., Pavon-Jordan, D., Quante, M., Reckermann, M., Rutgersson, A., Savchuk, O. P., Stendel, M., Tuomi, L., Viitasalo, M., Weisse, R., and Zhang, W. Y.: Climate change in the Baltic Sea region: a summary, Earth. Syst. Dynam., 13, 457–593, https://doi.org/10.5194/esd-13-457-2022, 2022.
Meyers, P. A.: Preservation of Elemental and Isotopic Source Identification of Sedimentary Organic-Matter, Chem. Geol., 114, 289–302, https://doi.org/10.1016/0009-2541(94)90059-0, 1994.
Morford, J. L., Martin, W. R., and Carney, C. M.: Uranium diagenesis in sediments underlying bottom waters with high oxygen content, Geochim. Cosmochim. Ac., 73, 2920–2937, https://doi.org/10.1016/j.gca.2009.02.014, 2009.
Morford, J. L., Martin, W. R., Kalnejais, L. H., Francois, R., Bothner, M., and Karle, I. M.: Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA, Geochim. Cosmochim. Ac., 71, 895–917, https://doi.org/10.1016/j.gca.2006.10.016, 2007.
Morin, G., Mangeret, A., Othmane, G., Stetten, L., Seder-Colomina, M., Brest, J., Ona-Nguema, G., Bassot, S., Courbet, C., Guillevic, J., Thouvenot, A., Mathon, O., Proux, O., and Bargar, J. R.: Mononuclear U(IV) complexes and ningyoite as major uranium species in lake sediments, Geochem. Perspect. Lett., 2, 95–105, https://doi.org/10.7185/geochemlet.1610, 2016.
Nordberg, K., Gustafsson, M., and Krantz, A. L.: Decreasing oxygen concentrations in the Gullmar Fjord, Sweden, as confirmed by benthic foraminifera, and the possible association with NAO, J. Marine. Syst., 23, 303–316, https://doi.org/10.1016/S0924-7963(99)00067-6, 2000.
Nordberg, K., Filipsson, H. L., Gustafsson, M., Harland, R., and Roos, P.: Climate, hydrographic variations and marine benthic hypoxia in Koljö Fjord, Sweden, J. Sea Res., 46, 187–200, https://doi.org/10.1016/S1385-1101(01)00084-3, 2001.
Ortiz-Bernad, I., Anderson, R. T., Vrionis, H. A., and Lovley, D. R.: Resistance of solid-phase U(VI) to microbial reduction during in situ bioremediation of uranium-contaminated groundwater, Appl. Environ. Microb., 70, 7558–7560, https://doi.org/10.1128/Aem.70.12.7558-7560.2004, 2004.
Paillard, D., Labeyrie, L., and Yiou, P.: AnalySeries 1.0: a Macintosh software for the analysis of geophysical time-series, Eos, 77, 379, https://doi.org/10.1029/96EO00259, 1996.
Paul, K. M.: Dataset for Paul et al., “Revisiting the applicability and constraints of molybdenum and uranium-based paleo redox proxies: comparing two contrasting sill fjords”, Biogeosciences, 2023, Zenodo [data set], https://doi.org/10.5281/zenodo.8399270, 2023.
Paul, K. M., van Helmond, N. A. G. M., Slomp, C. P., Jokinen, S. A., Virtasalo, J. J., Filipsson, H. L., and Jilbert, T.: Sedimentary molybdenum and uranium: Improving proxies for deoxygenation in coastal depositional environments, Chem. Geol., 615, 121203, https://doi.org/10.1016/j.chemgeo.2022.121203, 2023.
Pickard, G. L. and Stanton, B. R.: Pacific Fjords – A Review of Their Water Characteristics, in: Fjord Oceanography, edited by: Freeland, H. J., Farmer, D. M., and Levings, C. D., Springer US, Boston, MA, 1–51, https://doi.org/10.1007/978-1-4613-3105-6_1, 1980.
Polovodova Asteman, I., Filipsson, H. L., and Nordberg, K.: Tracing winter temperatures over the last two millennia using a north-east Atlantic coastal record, Clim. Past, 14, 1097–1118, https://doi.org/10.5194/cp-14-1097-2018, 2018.
Poulton, S. W. and Canfield, D. E.: Development of a sequential extraction procedure for iron: implications for iron partitioning in continentally derived particulates, Chem. Geol., 214, 209–221, 2005.
Prebble, J. G., Hinojosa, J. L., and Moy, C. M.: Palynofacies assemblages reflect sources of organic matter in New Zealand fjords, Cont. Shelf Res., 154, 19–25, https://doi.org/10.1016/j.csr.2017.12.009, 2018.
Raiswell, R. and Canfield, D. E.: The iron biogeochemical cycle past and present, Geochem. Perspect., 1, 1–220, https://doi.org/10.7185/geochempersp.1.1, 2012.
Rolison, J. M., Stirling, C. H., Middag, R., and Rijkenberg, M. J. A.: Uranium stable isotope fractionation in the Black Sea: Modern calibration of the 238U/235U paleo-redox proxy, Geochim. Cosmochim. Ac., 203, 69–88, https://doi.org/10.1016/j.gca.2016.12.014, 2017.
Rosenberg, R.: Negative Oxygen Trends in Swedish Coastal Bottom Waters, Mar. Pollut. Bull., 21, 335–339, https://doi.org/10.1016/0025-326x(90)90794-9, 1990.
Rudnick, R. L. and Gao, S.: Composition of the Continental Crust, Treat. Geochem., 4, 1–51, https://doi.org/10.1016/b978-0-08-095975-7.00301-6, 2014.
Russell, A. D. and Morford, J. L.: The behavior of redox-sensitive metals across a laminated-massive-laminated transition in Saanich Inlet, British Columbia, Mar. Geol., 174, 341–354, https://doi.org/10.1016/S0025-3227(00)00159-6, 2001.
Ruttenberg, K. C.: Development of a sequential extraction method for different forms of phosphorus in marine sediments, Limnol. Oceanogr., 37, 1460–1482, https://doi.org/10.4319/lo.1992.37.7.1460, 1992.
Scholz, F., McManus, J., and Sommer, S.: The manganese and iron shuttle in a modern euxinic basin and implications for molybdenum cycling at euxinic ocean margins, Chem. Geol., 355, 56–68, https://doi.org/10.1016/j.chemgeo.2013.07.006, 2013.
Scholz, F., Siebert, C., Dale, A. W., and Frank, M.: Intense molybdenum accumulation in sediments underneath a nitrogenous water column and implications for the reconstruction of paleo-redox conditions based on molybdenum isotopes, Geochim. Cosmochim. Ac., 213, 400–417, https://doi.org/10.1016/j.gca.2017.06.048, 2017.
Scholz, F., Baum, M., Siebert, C., Eroglu, S., Dale, A. W., Naumann, M., and Sommer, S.: Sedimentary molybdenum cycling in the aftermath of seawater inflow to the intermittently euxinic Gotland Deep, Central Baltic Sea, Chem. Geol., 491, 27–38, https://doi.org/10.1016/j.chemgeo.2018.04.031, 2018.
Scholz, F., Schmidt, M., Hensen, C., Eroglu, S., Geilert, S., Gutjahr, M., and Liebetrau, V.: Shelf-to-basin iron shuttle in the Guaymas Basin, Gulf of California, Geochim. Cosmochim. Ac., 261, 76–92, https://doi.org/10.1016/j.gca.2019.07.006, 2019.
Sharp, J. O., Schofield, E. J., Veeramani, H., Suvorova, E. I., Kennedy, D. W., Marshall, M. J., Mehta, A., Bargar, J. R., and Bernier-Latmani, R.: Structural Similarities between Biogenic Uraninites Produced by Phylogenetically and Metabolically Diverse Bacteria, Environ. Sci. Technol., 43, 8295–8301, https://doi.org/10.1021/es901281e, 2009.
Sharp, J. O., Lezama-Pacheco, J. S., Schofield, E. J., Junier, P., Ulrich, K.-U., Chinni, S., Veeramani, H., Margot-Roquier, C., Webb, S. M., Tebo, B. M., Giammar, D. E., Bargar, J. R., and Bernier-Latmani, R.: Uranium speciation and stability after reductive immobilization in aquifer sediments, Geochim. Cosmochim. Ac., 75, 6497–6510, https://doi.org/10.1016/j.gca.2011.08.022, 2011.
Sholkovitz, E. R.: The flocculation of dissolved Fe, Mn, Al, Cu, NI, Co and Cd during estuarine mixing, Earth Planet. Sci. Lett., 41, 77–86, https://doi.org/10.1016/0012-821X(78)90043-2, 1978.
Singh, A., Catalano, J. G., Ulrich, K. U., and Giammar, D. E.: Molecular-Scale Structure of Uranium(VI) Immobilized with Goethite and Phosphate, Environ. Sci. Technol., 46, 6594–6603, https://doi.org/10.1021/es300494x, 2012.
Slomp, C. P., Mort, H. P., Jilbert, T., Reed, D. C., Gustafsson, B. G., and Wolthers, M.: Coupled Dynamics of Iron and Phosphorus in Sediments of an Oligotrophic Coastal Basin and the Impact of Anaerobic Oxidation of Methane, Plos One, 8, e62386, https://doi.org/10.1371/journal.pone.0062386, 2013.
SMHI (Swedish Meteorological and Hydrological Institute): Svenskt HavsARKivs (SHARK) database: Water chemistry data 1950–2018, https://sharkweb.smhi.se/hamta-data/, last access: 3 September 2022.
Smith, R. W., Bianchi, T. S., Allison, M., Savage, C., and Galy, V.: High rates of organic carbon burial in fjord sediments globally, Nat. Geosci., 8, 450–453, https://doi.org/10.1038/Ngeo2421, 2015.
Soetaert, K., Petzoldt, T., and Meysman, F.: Marelac: Tools for Aquatic Sciences, R Package Version 2.1.10, https://cran.r-project.org/package=marelac, last access: 30 November 2022, 2010.
Suess, E.: Mineral Phases Formed in Anoxic Sediments by Microbial Decomposition of Organic-Matter, Geochim. Cosmochim. Ac., 43, 339–341, 343–352, https://doi.org/10.1016/0016-7037(79)90199-6, 1979.
Sulu-Gambari, F., Roepert, A., Jilbert, T., Hagens, M., Meysman, F. J. R., and Slomp, C. P.: Molybdenum dynamics in sediments of a seasonally-hypoxic coastal marine basin, Chem. Geol., 466, 627–640, https://doi.org/10.1016/j.chemgeo.2017.07.015, 2017.
Sundby, B., Martinez, P., and Gobeil, C.: Comparative geochemistry of cadmium, rhenium, uranium, and molybdenum in continental margin sediments, Geochim. Cosmochim. Ac., 68, 2485–2493, https://doi.org/10.1016/j.gca.2003.08.011, 2004.
Svansson, A.: Hydrography of the Gullmar fjord, Meddelande från Havsfiskelaboratoriet, Lysekil, 297, Institute of Hydrographic Research, Göteborg, 1–21, http://hdl.handle.net/2077/48767, last access: 11 December 2023, 1984.
Sverdrup, H. U., Johnson, M. W., and Fleming, R. H.: The Oceans: Their physics, chemistry, and general biology, Prentice-Hall, New York, 1087 pp., http://ark.cdlib.org/ark:/13030/kt167nb66r/, last access: 11 December 2023, 1942.
Syvitski, J. P. M. and Shaw, J.: Chapter 5 Sedimentology and Geomorphology of Fjords, in: Developments in Sedimentology, edited by: Perillo, G. M. E., Elsevier, 113–178, https://doi.org/10.1016/S0070-4571(05)80025-1, 1995.
Tessier, A., Campbell, P. G., and Bisson, M.: Sequential extraction procedure for the speciation of particulate trace metals, Anal. Chem., 51, 844–851, https://doi.org/10.1021/ac50043a017, 1979.
Thornton, S. F. and Mcmanus, J.: Application of Organic-Carbon and Nitrogen Stable-Isotope and C/N Ratios as Source Indicators of Organic-Matter Provenance in Estuarine Systems – Evidence from the Tay Estuary, Scotland, Estuar. Coast. Shelf. S., 38, 219–233, https://doi.org/10.1006/ecss.1994.1015, 1994.
Tribovillard, N., Algeo, T. J., Baudin, F., and Riboulleau, A.: Analysis of marine environmental conditions based onmolybdenum–uranium covariation – Applications to Mesozoic paleoceanography, Chem. Geol., 324/325, 46–58, https://doi.org/10.1016/j.chemgeo.2011.09.009, 2012.
Tribovillard, N., Algeo, T. J., Lyons, T., and Riboulleau, A.: Trace metals as paleoredox and paleoproductivity proxies: An update, Chem. Geol., 232, 12–32, https://doi.org/10.1016/j.chemgeo.2006.02.012, 2006.
Van der Weijden, C. H.: Pitfalls of normalization of marine geochemical data using a common divisor, Mar. Geol., 184, 167–187, https://doi.org/10.1016/S0025-3227(01)00297-3, 2002.
van Helmond, N. A. G. M., Jilbert, T., and Slomp, C. P.: Hypoxia in the Holocene Baltic Sea: Comparing modern versus past intervals using sedimentary trace metals, Chem. Geol., 493, 478–490, https://doi.org/10.1016/j.chemgeo.2018.06.028, 2018.
Van Mooy, B. A. S., Keil, R. G., and Devol, A. H.: Impact of suboxia on sinking particulate organic carbon: Enhanced carbon flux and preferential degradation of amino acids via denitrification, Geochim. Cosmochim. Ac., 66, 457–465, https://doi.org/10.1016/S0016-7037(01)00787-6, 2002.
Van Santvoort, P. J. M., De Lange, G. J., Thomson, J., Colley, S., Meysman, F. J. R., and Slomp, C. P.: Oxidation and origin of organic matter in surficial Eastern Mediterranean hemipelagic sediments, Aquat. Geochem., 8, 153–175, https://doi.org/10.1023/A:1024271706896, 2002.
Veeh, H. H.: Deposition of uranium from the ocean, Earth Planet. Sc. Lett., 3, 145–150, 1967.
Vorlicek, T. P., Helz, G. R., Chappaz, A., Vue, P., Vezina, A., and Hunter, W.: Molybdenum Burial Mechanism in Sulfidic Sediments: Iron-Sulfide Pathway, ACS Earth Space Chem., 2, 565–576, https://doi.org/10.1021/acsearthspacechem.8b00016, 2018.
Wagner, M., Chappaz, A., and Lyons, T. W.: Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS, Geochim. Cosmochim. Ac., 206, 18–29, https://doi.org/10.1016/j.gca.2017.02.018, 2017.
Wang, Y., Frutschi, M., Suvorova, E., Phrommavanh, V., Descostes, M., Osman, A. A., Geipel, G., and Bernier-Latmani, R.: Mobile uranium(IV)-bearing colloids in a mining-impacted wetland, Nat. Commun., 4, 2942, https://doi.org/10.1038/ncomms3942, 2013.
Wang, Y. F. and VanCappellen, P.: A multicomponent reactive transport model of early diagenesis: Application to redox cycling in coastal marine sediments, Geochim. Cosmochim. Ac., 60, 2993–3014, https://doi.org/10.1016/0016-7037(96)00140-8, 1996.
Wehrmann, L. M., Formolo, M. J., Owens, J. D., Raiswell, R., Ferdelman, T. G., Riedinger, N., and Lyons, T. W.: Iron and manganese speciation and cycling in glacially influenced high-latitude fjord sediments (West Spitsbergen, Svalbard): Evidence for a benthic recycling-transport mechanism, Geochim. Cosmochim. Ac., 141, 628–655, https://doi.org/10.1016/j.gca.2014.06.007, 2014.
Wittkop, C., Swanner, E. D., Grengs, A., Lambrecht, N., Fakhraee, M., Myrbo, A., Bray, A. W., Poulton, S. W., and Katsev, S.: Evaluating a primary carbonate pathway for manganese enrichments in reducing environments, Earth Planet. Sc. Lett., 538, 116201, https://doi.org/10.1016/j.epsl.2020.116201, 2020.
Yano, M., Yasukawa, K., Nakamura, K., Ikehara, M., and Kato, Y.: Geochemical Features of Redox-Sensitive Trace Metals in Sediments under Oxygen-Depleted Marine Environments, Minerals, 10, 1021, https://doi.org/10.3390/min10111021, 2020.
Zheng, Y., Anderson, R. F., Van Geen, A., and Fleisher, M. Q.: Remobilization of authigenic uranium in marine sediments by bioturbation, Geochim. Cosmochim. Ac., 66, 1759–1772, https://doi.org/10.1016/S0016-7037(01)00886-9, 2002a.
Zheng, Y., Anderson, R. F., Van Geen, A., and Fleisher, M. Q.: Preservation of particulate non-lithogenic uranium in marine sediments, Geochim. Cosmochim. Ac., 66, 3085–3092, https://doi.org/10.1016/S0016-7037(01)00632-9, 2002b.
Short summary
Seawater naturally contains trace metals such as Mo and U, which accumulate under low oxygen conditions on the seafloor. Previous studies have used sediment Mo and U contents as an archive of changing oxygen concentrations in coastal waters. Here we show that in fjords the use of Mo and U for this purpose may be impaired by additional processes. Our findings have implications for the reliable use of Mo and U to reconstruct oxygen changes in fjords.
Seawater naturally contains trace metals such as Mo and U, which accumulate under low oxygen...
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