Articles | Volume 18, issue 2
https://doi.org/10.5194/bg-18-637-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-18-637-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
28 Jan 2021
Research article |
| 28 Jan 2021
| 28 Jan 2021
Nitrate assimilation and regeneration in the Barents Sea: insights from nitrate isotopes
Robyn E. Tuerena
CORRESPONDING AUTHOR
School of GeoSciences, University of Edinburgh, James Hutton Rd,
Edinburgh, EH9 3FE, UK
now at: Scottish Association for Marine Science, Oban, Argyll, PA37 1QA, UK
Joanne Hopkins
National Oceanography Centre, 6 Brownlow Street, Liverpool, L3 5DA,
UK
Raja S. Ganeshram
School of GeoSciences, University of Edinburgh, James Hutton Rd,
Edinburgh, EH9 3FE, UK
Louisa Norman
School of Environmental Sciences, University of Liverpool, 4 Brownlow
St, Liverpool, L69 3GP, UK
Camille de la Vega
School of Environmental Sciences, University of Liverpool, 4 Brownlow
St, Liverpool, L69 3GP, UK
Rachel Jeffreys
School of Environmental Sciences, University of Liverpool, 4 Brownlow
St, Liverpool, L69 3GP, UK
Claire Mahaffey
School of Environmental Sciences, University of Liverpool, 4 Brownlow
St, Liverpool, L69 3GP, UK
Related authors
Adam Francis, Raja S. Ganeshram, Robyn E. Tuerena, Robert G. M. Spencer, Robert M. Holmes, Jennifer A. Rogers, and Claire Mahaffey
Biogeosciences, 20, 365–382, https://doi.org/10.5194/bg-20-365-2023, https://doi.org/10.5194/bg-20-365-2023, 2023
Short summary
Short summary
Climate change is causing extensive permafrost degradation and nutrient releases into rivers with great ecological impacts on the Arctic Ocean. We focused on nitrogen (N) release from this degradation and associated cycling using N isotopes, an understudied area. Many N species are released at degradation sites with exchanges between species. N inputs from permafrost degradation and seasonal river N trends were identified using isotopes, helping to predict climate change impacts.
Marta Santos-Garcia, Raja S. Ganeshram, Robyn E. Tuerena, Margot C. F. Debyser, Katrine Husum, Philipp Assmy, and Haakon Hop
Biogeosciences, 19, 5973–6002, https://doi.org/10.5194/bg-19-5973-2022, https://doi.org/10.5194/bg-19-5973-2022, 2022
Short summary
Short summary
Terrestrial sources of nitrate are important contributors to the nutrient pool in the fjords of Kongsfjorden and Rijpfjorden in Svalbard during the summer, and they sustain most of the fjord primary productivity. Ongoing tidewater glacier retreat is postulated to favour light limitation and less dynamic circulation in fjords. This is suggested to encourage the export of nutrients to the middle and outer part of the fjord system, which may enhance primary production within and in offshore areas.
Margot C. F. Debyser, Laetitia Pichevin, Robyn E. Tuerena, Paul A. Dodd, Antonia Doncila, and Raja S. Ganeshram
Biogeosciences, 19, 5499–5520, https://doi.org/10.5194/bg-19-5499-2022, https://doi.org/10.5194/bg-19-5499-2022, 2022
Short summary
Short summary
We focus on the exchange of key nutrients for algae production between the Arctic and Atlantic oceans through the Fram Strait. We show that the export of dissolved silicon here is controlled by the availability of nitrate which is influenced by denitrification on Arctic shelves. We suggest that any future changes in the river inputs of silica and changes in denitrification due to climate change will impact the amount of silicon exported, with impacts on Atlantic algal productivity and ecology.
Charlotte Haugk, Loeka L. Jongejans, Kai Mangelsdorf, Matthias Fuchs, Olga Ogneva, Juri Palmtag, Gesine Mollenhauer, Paul J. Mann, P. Paul Overduin, Guido Grosse, Tina Sanders, Robyn E. Tuerena, Lutz Schirrmeister, Sebastian Wetterich, Alexander Kizyakov, Cornelia Karger, and Jens Strauss
Biogeosciences, 19, 2079–2094, https://doi.org/10.5194/bg-19-2079-2022, https://doi.org/10.5194/bg-19-2079-2022, 2022
Short summary
Short summary
Buried animal and plant remains (carbon) from the last ice age were freeze-locked in permafrost. At an extremely fast eroding permafrost cliff in the Lena Delta (Siberia), we found this formerly frozen carbon well preserved. Our results show that ongoing degradation releases substantial amounts of this carbon, making it available for future carbon emissions. This mobilisation at the studied cliff and also similarly eroding sites bear the potential to affect rivers and oceans negatively.
Maria-Theresia Verwega, Christopher J. Somes, Markus Schartau, Robyn Elizabeth Tuerena, Anne Lorrain, Andreas Oschlies, and Thomas Slawig
Earth Syst. Sci. Data, 13, 4861–4880, https://doi.org/10.5194/essd-13-4861-2021, https://doi.org/10.5194/essd-13-4861-2021, 2021
Short summary
Short summary
This work describes a ready-to-use collection of particulate organic carbon stable isotope ratio data sets. It covers the 1960s–2010s and all main oceans, providing meta-information and gridded data. The best coverage exists in Atlantic, Indian and Southern Ocean surface waters during the 1990s. It indicates no major difference between methods and shows decreasing values towards high latitudes, with the lowest in the Southern Ocean, and a long-term decline in all regions but the Southern Ocean.
Robyn E. Tuerena, Raja S. Ganeshram, Matthew P. Humphreys, Thomas J. Browning, Heather Bouman, and Alexander P. Piotrowski
Biogeosciences, 16, 3621–3635, https://doi.org/10.5194/bg-16-3621-2019, https://doi.org/10.5194/bg-16-3621-2019, 2019
Short summary
Short summary
The carbon isotopes in algae can be used to predict food sources and environmental change. We explore how dissolved carbon is taken up by algae in the South Atlantic Ocean and how this affects their carbon isotope signature. We find that cell size controls isotope fractionation. We use our results to investigate how climate change may impact the carbon isotopes in algae. We suggest a shift to smaller algae in this region would decrease the carbon isotope ratio at the base of the food web.
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
Short summary
Short summary
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.
Adam Francis, Raja S. Ganeshram, Robyn E. Tuerena, Robert G. M. Spencer, Robert M. Holmes, Jennifer A. Rogers, and Claire Mahaffey
Biogeosciences, 20, 365–382, https://doi.org/10.5194/bg-20-365-2023, https://doi.org/10.5194/bg-20-365-2023, 2023
Short summary
Short summary
Climate change is causing extensive permafrost degradation and nutrient releases into rivers with great ecological impacts on the Arctic Ocean. We focused on nitrogen (N) release from this degradation and associated cycling using N isotopes, an understudied area. Many N species are released at degradation sites with exchanges between species. N inputs from permafrost degradation and seasonal river N trends were identified using isotopes, helping to predict climate change impacts.
Marta Santos-Garcia, Raja S. Ganeshram, Robyn E. Tuerena, Margot C. F. Debyser, Katrine Husum, Philipp Assmy, and Haakon Hop
Biogeosciences, 19, 5973–6002, https://doi.org/10.5194/bg-19-5973-2022, https://doi.org/10.5194/bg-19-5973-2022, 2022
Short summary
Short summary
Terrestrial sources of nitrate are important contributors to the nutrient pool in the fjords of Kongsfjorden and Rijpfjorden in Svalbard during the summer, and they sustain most of the fjord primary productivity. Ongoing tidewater glacier retreat is postulated to favour light limitation and less dynamic circulation in fjords. This is suggested to encourage the export of nutrients to the middle and outer part of the fjord system, which may enhance primary production within and in offshore areas.
Margot C. F. Debyser, Laetitia Pichevin, Robyn E. Tuerena, Paul A. Dodd, Antonia Doncila, and Raja S. Ganeshram
Biogeosciences, 19, 5499–5520, https://doi.org/10.5194/bg-19-5499-2022, https://doi.org/10.5194/bg-19-5499-2022, 2022
Short summary
Short summary
We focus on the exchange of key nutrients for algae production between the Arctic and Atlantic oceans through the Fram Strait. We show that the export of dissolved silicon here is controlled by the availability of nitrate which is influenced by denitrification on Arctic shelves. We suggest that any future changes in the river inputs of silica and changes in denitrification due to climate change will impact the amount of silicon exported, with impacts on Atlantic algal productivity and ecology.
Charlotte Haugk, Loeka L. Jongejans, Kai Mangelsdorf, Matthias Fuchs, Olga Ogneva, Juri Palmtag, Gesine Mollenhauer, Paul J. Mann, P. Paul Overduin, Guido Grosse, Tina Sanders, Robyn E. Tuerena, Lutz Schirrmeister, Sebastian Wetterich, Alexander Kizyakov, Cornelia Karger, and Jens Strauss
Biogeosciences, 19, 2079–2094, https://doi.org/10.5194/bg-19-2079-2022, https://doi.org/10.5194/bg-19-2079-2022, 2022
Short summary
Short summary
Buried animal and plant remains (carbon) from the last ice age were freeze-locked in permafrost. At an extremely fast eroding permafrost cliff in the Lena Delta (Siberia), we found this formerly frozen carbon well preserved. Our results show that ongoing degradation releases substantial amounts of this carbon, making it available for future carbon emissions. This mobilisation at the studied cliff and also similarly eroding sites bear the potential to affect rivers and oceans negatively.
Maria-Theresia Verwega, Christopher J. Somes, Markus Schartau, Robyn Elizabeth Tuerena, Anne Lorrain, Andreas Oschlies, and Thomas Slawig
Earth Syst. Sci. Data, 13, 4861–4880, https://doi.org/10.5194/essd-13-4861-2021, https://doi.org/10.5194/essd-13-4861-2021, 2021
Short summary
Short summary
This work describes a ready-to-use collection of particulate organic carbon stable isotope ratio data sets. It covers the 1960s–2010s and all main oceans, providing meta-information and gridded data. The best coverage exists in Atlantic, Indian and Southern Ocean surface waters during the 1990s. It indicates no major difference between methods and shows decreasing values towards high latitudes, with the lowest in the Southern Ocean, and a long-term decline in all regions but the Southern Ocean.
Robyn E. Tuerena, Raja S. Ganeshram, Matthew P. Humphreys, Thomas J. Browning, Heather Bouman, and Alexander P. Piotrowski
Biogeosciences, 16, 3621–3635, https://doi.org/10.5194/bg-16-3621-2019, https://doi.org/10.5194/bg-16-3621-2019, 2019
Short summary
Short summary
The carbon isotopes in algae can be used to predict food sources and environmental change. We explore how dissolved carbon is taken up by algae in the South Atlantic Ocean and how this affects their carbon isotope signature. We find that cell size controls isotope fractionation. We use our results to investigate how climate change may impact the carbon isotopes in algae. We suggest a shift to smaller algae in this region would decrease the carbon isotope ratio at the base of the food web.
K. E. Larkin, A. J. Gooday, C. Woulds, R. M. Jeffreys, M. Schwartz, G. Cowie, C. Whitcraft, L. Levin, J. R. Dick, and D. W. Pond
Biogeosciences, 11, 3729–3738, https://doi.org/10.5194/bg-11-3729-2014, https://doi.org/10.5194/bg-11-3729-2014, 2014
Related subject area
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Sedimentary organic matter signature hints at the phytoplankton-driven biological carbon pump in the central Arabian Sea
Hydrological cycle amplification imposes spatial patterns on the climate change response of ocean pH and carbonate chemistry
Assessing the tropical Atlantic biogeochemical processes in the Norwegian Earth System Model
Evolution of oxygen and stratification and their relationship in the North Pacific Ocean in CMIP6 Earth system models
Evaluation of CMIP6 model performance in simulating historical biogeochemistry across the southern South China Sea
Drivers of decadal trends in the ocean carbon sink in the past, present, and future in Earth system models
Anthropogenic carbon storage and its decadal changes in the Atlantic between 1990–2020
Ocean alkalinity enhancement impacts: regrowth of marine microalgae in alkaline mineral concentrations simulating the initial concentrations after ship-based dispersions
Climatic controls on metabolic constraints in the ocean
Effects of grain size and seawater salinity on magnesium hydroxide dissolution and secondary calcium carbonate precipitation kinetics: implications for ocean alkalinity enhancement
Short-term response of Emiliania huxleyi growth and morphology to abrupt salinity stress
Assessing the impact of CO2-equilibrated ocean alkalinity enhancement on microbial metabolic rates in an oligotrophic system
Ocean Acidification trends and Carbonate System dynamics in the North Atlantic Subpolar Gyre during 2009–2019
Phosphomonoesterase and phosphodiesterase activities in the eastern Mediterranean in two contrasting seasonal situations
Net primary production annual maxima in the North Atlantic projected to shift in the 21st century
Testing the influence of light on nitrite cycling in the eastern tropical North Pacific
Loss of nitrogen via anaerobic ammonium oxidation (anammox) in the California Current system during the late Quaternary
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Linking northeastern North Pacific oxygen changes to upstream surface outcrop variations
Underestimation of multi-decadal global O2 loss due to an optimal interpolation method
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The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes
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Fossil coccolith morphological attributes as a new proxy for deep ocean carbonate chemistry
Reconstructing ocean carbon storage with CMIP6 Earth system models and synthetic Argo observations
Using machine learning and Biogeochemical-Argo (BGC-Argo) floats to assess biogeochemical models and optimize observing system design
The representation of alkalinity and the carbonate pump from CMIP5 to CMIP6 Earth system models and implications for the carbon cycle
Model estimates of metazoans' contributions to the biological carbon pump
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Nitrite cycling in the primary nitrite maxima of the eastern tropical North Pacific
Hotspots and drivers of compound marine heatwaves and low net primary production extremes
Ecosystem impacts of marine heat waves in the northeast Pacific
Tracing the role of Arctic shelf processes in Si and N cycling and export through the Fram Strait: insights from combined silicon and nitrate isotopes
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Observation-constrained estimates of the global ocean carbon sink from Earth system models
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We analysed sea surface temperature (SST) proxy and plankton biomarkers in sediments that accumulate sinking material signatures from surface waters in the central Arabian Sea (21°–11° N, 64° E), a tropical basin impacted by monsoons. We saw a north–south SST gradient, and the biological proxies showed more organic matter from larger algae in the north. Smaller algae and zooplankton were more numerous in the south. These trends were related to ocean–atmospheric processes and oxygen availability.
Allison Hogikyan and Laure Resplandy
Biogeosciences, 21, 4621–4636, https://doi.org/10.5194/bg-21-4621-2024, https://doi.org/10.5194/bg-21-4621-2024, 2024
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Rising atmospheric CO2 influences ocean carbon chemistry, leading to ocean acidification. Global warming introduces spatial patterns in the intensity of ocean acidification. We show that the most prominent spatial patterns are controlled by warming-driven changes in rainfall and evaporation, not by the direct effect of warming on carbon chemistry and pH. These evaporation and rainfall patterns oppose acidification in saltier parts of the ocean and enhance acidification in fresher regions.
Shunya Koseki, Lander R. Crespo, Jerry Tjiputra, Filippa Fransner, Noel S. Keenlyside, and David Rivas
Biogeosciences, 21, 4149–4168, https://doi.org/10.5194/bg-21-4149-2024, https://doi.org/10.5194/bg-21-4149-2024, 2024
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We investigated how the physical biases of an Earth system model influence the marine biogeochemical processes in the tropical Atlantic. With four different configurations of the model, we have shown that the versions with better SST reproduction tend to better represent the primary production and air–sea CO2 flux in terms of climatology, seasonal cycle, and response to climate variability.
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Biogeosciences, 21, 3985–4005, https://doi.org/10.5194/bg-21-3985-2024, https://doi.org/10.5194/bg-21-3985-2024, 2024
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Biogeosciences, 21, 4007–4035, https://doi.org/10.5194/bg-21-4007-2024, https://doi.org/10.5194/bg-21-4007-2024, 2024
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This study stands out for thoroughly examining CMIP6 ESMs' ability to simulate biogeochemical variables in the southern South China Sea, an economically important region. It assesses variables like chlorophyll, phytoplankton, nitrate, and oxygen on annual and seasonal scales. While global assessments exist, this study addresses a gap by objectively ranking 13 CMIP6 ocean biogeochemistry models' performance at a regional level, focusing on replicating specific observed biogeochemical variables.
Jens Terhaar
Biogeosciences, 21, 3903–3926, https://doi.org/10.5194/bg-21-3903-2024, https://doi.org/10.5194/bg-21-3903-2024, 2024
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Despite the ocean’s importance in the carbon cycle and hence the climate, observing the ocean carbon sink remains challenging. Here, I use an ensemble of 12 models to understand drivers of decadal trends of the past, present, and future ocean carbon sink. I show that 80 % of the decadal trends in the multi-model mean ocean carbon sink can be explained by changes in decadal trends in atmospheric CO2. The remaining 20 % are due to internal climate variability and ocean heat uptake.
Reiner Steinfeldt, Monika Rhein, and Dagmar Kieke
Biogeosciences, 21, 3839–3867, https://doi.org/10.5194/bg-21-3839-2024, https://doi.org/10.5194/bg-21-3839-2024, 2024
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We calculate the amount of anthropogenic carbon (Cant) in the Atlantic for the years 1990, 2000, 2010 and 2020. Cant is the carbon that is taken up by the ocean as a result of humanmade CO2 emissions. To determine the amount of Cant, we apply a technique that is based on the observations of other humanmade gases (e.g., chlorofluorocarbons). Regionally, changes in ocean ventilation have an impact on the storage of Cant. Overall, the increase in Cant is driven by the rising CO2 in the atmosphere.
Stephanie Delacroix, Tor Jensen Nystuen, August E. Dessen Tobiesen, Andrew L. King, and Erik Höglund
Biogeosciences, 21, 3677–3690, https://doi.org/10.5194/bg-21-3677-2024, https://doi.org/10.5194/bg-21-3677-2024, 2024
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The addition of alkaline minerals into the ocean might reduce excessive anthropogenic CO2 emissions. Magnesium hydroxide can be added in large amounts because of its low seawater solubility without reaching harmful pH levels. The toxicity effect results of magnesium hydroxide, by simulating the expected concentrations from a ship's dispersion scenario, demonstrated low impacts on both sensitive and local assemblages of marine microalgae when compared to calcium hydroxide.
Precious Mongwe, Matthew Long, Takamitsu Ito, Curtis Deutsch, and Yeray Santana-Falcón
Biogeosciences, 21, 3477–3490, https://doi.org/10.5194/bg-21-3477-2024, https://doi.org/10.5194/bg-21-3477-2024, 2024
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We use a collection of measurements that capture the physiological sensitivity of organisms to temperature and oxygen and a CESM1 large ensemble to investigate how natural climate variations and climate warming will impact the ability of marine heterotrophic marine organisms to support habitats in the future. We find that warming and dissolved oxygen loss over the next several decades will reduce the volume of ocean habitats and will increase organisms' vulnerability to extremes.
Charly A. Moras, Tyler Cyronak, Lennart T. Bach, Renaud Joannes-Boyau, and Kai G. Schulz
Biogeosciences, 21, 3463–3475, https://doi.org/10.5194/bg-21-3463-2024, https://doi.org/10.5194/bg-21-3463-2024, 2024
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We investigate the effects of mineral grain size and seawater salinity on magnesium hydroxide dissolution and calcium carbonate precipitation kinetics for ocean alkalinity enhancement. Salinity did not affect the dissolution, but calcium carbonate formed earlier at lower salinities due to the lower magnesium and dissolved organic carbon concentrations. Smaller grain sizes dissolved faster but calcium carbonate precipitated earlier, suggesting that medium grain sizes are optimal for kinetics.
Rosie M. Sheward, Christina Gebühr, Jörg Bollmann, and Jens O. Herrle
Biogeosciences, 21, 3121–3141, https://doi.org/10.5194/bg-21-3121-2024, https://doi.org/10.5194/bg-21-3121-2024, 2024
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How quickly do marine microorganisms respond to salinity stress? Our experiments with the calcifying marine plankton Emiliania huxleyi show that growth and cell morphology responded to salinity stress within as little as 24–48 hours, demonstrating that morphology and calcification are sensitive to salinity over a range of timescales. Our results have implications for understanding the short-term role of E. huxleyi in biogeochemical cycles and in size-based paleoproxies for salinity.
Laura Marín-Samper, Javier Arístegui, Nauzet Hernández-Hernández, Joaquín Ortiz, Stephen D. Archer, Andrea Ludwig, and Ulf Riebesell
Biogeosciences, 21, 2859–2876, https://doi.org/10.5194/bg-21-2859-2024, https://doi.org/10.5194/bg-21-2859-2024, 2024
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Our planet is facing a climate crisis. Scientists are working on innovative solutions that will aid in capturing the hard to abate emissions before it is too late. Exciting research reveals that ocean alkalinity enhancement, a key climate change mitigation strategy, does not harm phytoplankton, the cornerstone of marine ecosystems. Through meticulous study, we may have uncovered a positive relationship: up to a specific limit, enhancing ocean alkalinity boosts photosynthesis by certain species.
David Curbelo-Hernández, Fiz F. Pérez, Melchor González-Dávila, Sergey V. Gladyshev, Aridane G. González, David González-Santana, Antón Velo, Alexey Sokov, and J. Magdalena Santana-Casiano
EGUsphere, https://doi.org/10.5194/egusphere-2024-1388, https://doi.org/10.5194/egusphere-2024-1388, 2024
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The study evaluated CO2-carbonate system dynamics in the North Atlantic Subpolar Gyre from 2009 to 2019. Significant ocean acidification, largely due to rising anthropogenic CO2 levels, was found. Cooling, freshening, and enhanced convective processes intensified this trend, affecting calcite and aragonite saturation. The findings contribute to a deeper understanding of Ocean Acidification and improve our knowledge about its impact on marine ecosystems.
France Van Wambeke, Pascal Conan, Mireille Pujo-Pay, Vincent Taillandier, Olivier Crispi, Alexandra Pavlidou, Sandra Nunige, Morgane Didry, Christophe Salmeron, and Elvira Pulido-Villena
Biogeosciences, 21, 2621–2640, https://doi.org/10.5194/bg-21-2621-2024, https://doi.org/10.5194/bg-21-2621-2024, 2024
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Phosphomonoesterase (PME) and phosphodiesterase (PDE) activities over the epipelagic zone are described in the eastern Mediterranean Sea in winter and autumn. The types of concentration kinetics obtained for PDE (saturation at 50 µM, high Km, high turnover times) compared to those of PME (saturation at 1 µM, low Km, low turnover times) are discussed in regard to the possible inequal distribution of PDE and PME in the size continuum of organic material and accessibility to phosphodiesters.
Jenny Hieronymus, Magnus Hieronymus, Matthias Gröger, Jörg Schwinger, Raffaele Bernadello, Etienne Tourigny, Valentina Sicardi, Itzel Ruvalcaba Baroni, and Klaus Wyser
Biogeosciences, 21, 2189–2206, https://doi.org/10.5194/bg-21-2189-2024, https://doi.org/10.5194/bg-21-2189-2024, 2024
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The timing of the net primary production annual maxima in the North Atlantic in the period 1750–2100 is investigated using two Earth system models and the high-emissions scenario SSP5-8.5. It is found that, for most of the region, the annual maxima occur progressively earlier, with the most change occurring after the year 2000. Shifts in the seasonality of the primary production may impact the entire ecosystem, which highlights the need for long-term monitoring campaigns in this area.
Nicole M. Travis, Colette L. Kelly, and Karen L. Casciotti
Biogeosciences, 21, 1985–2004, https://doi.org/10.5194/bg-21-1985-2024, https://doi.org/10.5194/bg-21-1985-2024, 2024
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We conducted experimental manipulations of light level on microbial communities from the primary nitrite maximum. Overall, while individual microbial processes have different directions and magnitudes in their response to increasing light, the net community response is a decline in nitrite production with increasing light. We conclude that while increased light may decrease net nitrite production, high-light conditions alone do not exclude nitrification from occurring in the surface ocean.
Zoë Rebecca van Kemenade, Zeynep Erdem, Ellen Christine Hopmans, Jaap Smede Sinninghe Damsté, and Darci Rush
Biogeosciences, 21, 1517–1532, https://doi.org/10.5194/bg-21-1517-2024, https://doi.org/10.5194/bg-21-1517-2024, 2024
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The California Current system (CCS) hosts the eastern subtropical North Pacific oxygen minimum zone (ESTNP OMZ). This study shows anaerobic ammonium oxidizing (anammox) bacteria cause a loss of bioavailable nitrogen (N) in the ESTNP OMZ throughout the late Quaternary. Anammox occurred during both glacial and interglacial periods and was driven by the supply of organic matter and changes in ocean currents. These findings may have important consequences for biogeochemical models of the CCS.
Cathy Wimart-Rousseau, Tobias Steinhoff, Birgit Klein, Henry Bittig, and Arne Körtzinger
Biogeosciences, 21, 1191–1211, https://doi.org/10.5194/bg-21-1191-2024, https://doi.org/10.5194/bg-21-1191-2024, 2024
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The marine CO2 system can be measured independently and continuously by BGC-Argo floats since numerous pH sensors have been developed to suit these autonomous measurements platforms. By applying the Argo correction routines to float pH data acquired in the subpolar North Atlantic Ocean, we report the uncertainty and lack of objective criteria associated with the choice of the reference method as well the reference depth for the pH correction.
Sabine Mecking and Kyla Drushka
Biogeosciences, 21, 1117–1133, https://doi.org/10.5194/bg-21-1117-2024, https://doi.org/10.5194/bg-21-1117-2024, 2024
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This study investigates whether northeastern North Pacific oxygen changes may be caused by surface density changes in the northwest as water moves along density horizons from the surface into the subsurface ocean. A correlation is found with a lag that about matches the travel time of water from the northwest to the northeast. Salinity is the main driver causing decadal changes in surface density, whereas salinity and temperature contribute about equally to long-term declining density trends.
Takamitsu Ito, Hernan E. Garcia, Zhankun Wang, Shoshiro Minobe, Matthew C. Long, Just Cebrian, James Reagan, Tim Boyer, Christopher Paver, Courtney Bouchard, Yohei Takano, Seth Bushinsky, Ahron Cervania, and Curtis A. Deutsch
Biogeosciences, 21, 747–759, https://doi.org/10.5194/bg-21-747-2024, https://doi.org/10.5194/bg-21-747-2024, 2024
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This study aims to estimate how much oceanic oxygen has been lost and its uncertainties. One major source of uncertainty comes from the statistical gap-filling methods. Outputs from Earth system models are used to generate synthetic observations where oxygen data are extracted from the model output at the location and time of historical oceanographic cruises. Reconstructed oxygen trend is approximately two-thirds of the true trend.
Robert W. Izett, Katja Fennel, Adam C. Stoer, and David P. Nicholson
Biogeosciences, 21, 13–47, https://doi.org/10.5194/bg-21-13-2024, https://doi.org/10.5194/bg-21-13-2024, 2024
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This paper provides an overview of the capacity to expand the global coverage of marine primary production estimates using autonomous ocean-going instruments, called Biogeochemical-Argo floats. We review existing approaches to quantifying primary production using floats, provide examples of the current implementation of the methods, and offer insights into how they can be better exploited. This paper is timely, given the ongoing expansion of the Biogeochemical-Argo array.
Qian Liu, Yingjie Liu, and Xiaofeng Li
Biogeosciences, 20, 4857–4874, https://doi.org/10.5194/bg-20-4857-2023, https://doi.org/10.5194/bg-20-4857-2023, 2023
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In the Southern Ocean, abundant eddies behave opposite to our expectations. That is, anticyclonic (cyclonic) eddies are cold (warm). By investigating the variations of physical and biochemical parameters in eddies, we find that abnormal eddies have unique and significant effects on modulating the parameters. This study fills a gap in understanding the effects of abnormal eddies on physical and biochemical parameters in the Southern Ocean.
Caroline Ulses, Claude Estournel, Patrick Marsaleix, Karline Soetaert, Marine Fourrier, Laurent Coppola, Dominique Lefèvre, Franck Touratier, Catherine Goyet, Véronique Guglielmi, Fayçal Kessouri, Pierre Testor, and Xavier Durrieu de Madron
Biogeosciences, 20, 4683–4710, https://doi.org/10.5194/bg-20-4683-2023, https://doi.org/10.5194/bg-20-4683-2023, 2023
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Deep convection plays a key role in the circulation, thermodynamics, and biogeochemical cycles in the Mediterranean Sea, considered to be a hotspot of biodiversity and climate change. In this study, we investigate the seasonal and annual budget of dissolved inorganic carbon in the deep-convection area of the northwestern Mediterranean Sea.
Daniela König and Alessandro Tagliabue
Biogeosciences, 20, 4197–4212, https://doi.org/10.5194/bg-20-4197-2023, https://doi.org/10.5194/bg-20-4197-2023, 2023
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Using model simulations, we show that natural and anthropogenic changes in the global climate leave a distinct fingerprint in the isotopic signatures of iron in the surface ocean. We find that these climate effects on iron isotopes are often caused by the redistribution of iron from different external sources to the ocean, due to changes in ocean currents, and by changes in algal growth, which take up iron. Thus, isotopes may help detect climate-induced changes in iron supply and algal uptake.
Chloé Baumas, Robin Fuchs, Marc Garel, Jean-Christophe Poggiale, Laurent Memery, Frédéric A. C. Le Moigne, and Christian Tamburini
Biogeosciences, 20, 4165–4182, https://doi.org/10.5194/bg-20-4165-2023, https://doi.org/10.5194/bg-20-4165-2023, 2023
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Through the sink of particles in the ocean, carbon (C) is exported and sequestered when reaching 1000 m. Attempts to quantify C exported vs. C consumed by heterotrophs have increased. Yet most of the conducted estimations have led to C demands several times higher than C export. The choice of parameters greatly impacts the results. As theses parameters are overlooked, non-accurate values are often used. In this study we show that C budgets can be well balanced when using appropriate values.
Anna Belcher, Sian F. Henley, Katharine Hendry, Marianne Wootton, Lisa Friberg, Ursula Dallman, Tong Wang, Christopher Coath, and Clara Manno
Biogeosciences, 20, 3573–3591, https://doi.org/10.5194/bg-20-3573-2023, https://doi.org/10.5194/bg-20-3573-2023, 2023
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The oceans play a crucial role in the uptake of atmospheric carbon dioxide, particularly the Southern Ocean. The biological pumping of carbon from the surface to the deep ocean is key to this. Using sediment trap samples from the Scotia Sea, we examine biogeochemical fluxes of carbon, nitrogen, and biogenic silica and their stable isotope compositions. We find phytoplankton community structure and physically mediated processes are important controls on particulate fluxes to the deep ocean.
Asmita Singh, Susanne Fietz, Sandy J. Thomalla, Nicolas Sanchez, Murat V. Ardelan, Sébastien Moreau, Hanna M. Kauko, Agneta Fransson, Melissa Chierici, Saumik Samanta, Thato N. Mtshali, Alakendra N. Roychoudhury, and Thomas J. Ryan-Keogh
Biogeosciences, 20, 3073–3091, https://doi.org/10.5194/bg-20-3073-2023, https://doi.org/10.5194/bg-20-3073-2023, 2023
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Despite the scarcity of iron in the Southern Ocean, seasonal blooms occur due to changes in nutrient and light availability. Surprisingly, during an autumn bloom in the Antarctic sea-ice zone, the results from incubation experiments showed no significant photophysiological response of phytoplankton to iron addition. This suggests that ambient iron concentrations were sufficient, challenging the notion of iron deficiency in the Southern Ocean through extended iron-replete post-bloom conditions.
Benoît Pasquier, Mark Holzer, Matthew A. Chamberlain, Richard J. Matear, Nathaniel L. Bindoff, and François W. Primeau
Biogeosciences, 20, 2985–3009, https://doi.org/10.5194/bg-20-2985-2023, https://doi.org/10.5194/bg-20-2985-2023, 2023
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Modeling the ocean's carbon and oxygen cycles accurately is challenging. Parameter optimization improves the fit to observed tracers but can introduce artifacts in the biological pump. Organic-matter production and subsurface remineralization rates adjust to compensate for circulation biases, changing the pathways and timescales with which nutrients return to the surface. Circulation biases can thus strongly alter the system’s response to ecological change, even when parameters are optimized.
Priyanka Banerjee
Biogeosciences, 20, 2613–2643, https://doi.org/10.5194/bg-20-2613-2023, https://doi.org/10.5194/bg-20-2613-2023, 2023
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This study shows that atmospheric deposition is the most important source of iron to the upper northern Indian Ocean for phytoplankton growth. This is followed by iron from continental-shelf sediment. Phytoplankton increase following iron addition is possible only with high background levels of nitrate. Vertical mixing is the most important physical process supplying iron to the upper ocean in this region throughout the year. The importance of ocean currents in supplying iron varies seasonally.
Iris Kriest, Julia Getzlaff, Angela Landolfi, Volkmar Sauerland, Markus Schartau, and Andreas Oschlies
Biogeosciences, 20, 2645–2669, https://doi.org/10.5194/bg-20-2645-2023, https://doi.org/10.5194/bg-20-2645-2023, 2023
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Global biogeochemical ocean models are often subjectively assessed and tuned against observations. We applied different strategies to calibrate a global model against observations. Although the calibrated models show similar tracer distributions at the surface, they differ in global biogeochemical fluxes, especially in global particle flux. Simulated global volume of oxygen minimum zones varies strongly with calibration strategy and over time, rendering its temporal extrapolation difficult.
John C. Tracey, Andrew R. Babbin, Elizabeth Wallace, Xin Sun, Katherine L. DuRussel, Claudia Frey, Donald E. Martocello III, Tyler Tamasi, Sergey Oleynik, and Bess B. Ward
Biogeosciences, 20, 2499–2523, https://doi.org/10.5194/bg-20-2499-2023, https://doi.org/10.5194/bg-20-2499-2023, 2023
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Nitrogen (N) is essential for life; thus, its availability plays a key role in determining marine productivity. Using incubations of seawater spiked with a rare form of N measurable on a mass spectrometer, we quantified microbial pathways that determine marine N availability. The results show that pathways that recycle N have higher rates than those that result in its loss from biomass and present new evidence for anaerobic nitrite oxidation, a process long thought to be strictly aerobic.
Amanda Gerotto, Hongrui Zhang, Renata Hanae Nagai, Heather M. Stoll, Rubens César Lopes Figueira, Chuanlian Liu, and Iván Hernández-Almeida
Biogeosciences, 20, 1725–1739, https://doi.org/10.5194/bg-20-1725-2023, https://doi.org/10.5194/bg-20-1725-2023, 2023
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Based on the analysis of the response of coccolithophores’ morphological attributes in a laboratory dissolution experiment and surface sediment samples from the South China Sea, we proposed that the thickness shape (ks) factor of fossil coccoliths together with the normalized ks variation, which is the ratio of the standard deviation of ks (σ) over the mean ks (σ/ks), is a robust and novel proxy to reconstruct past changes in deep ocean carbon chemistry.
Katherine E. Turner, Doug M. Smith, Anna Katavouta, and Richard G. Williams
Biogeosciences, 20, 1671–1690, https://doi.org/10.5194/bg-20-1671-2023, https://doi.org/10.5194/bg-20-1671-2023, 2023
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We present a new method for reconstructing ocean carbon using climate models and temperature and salinity observations. To test this method, we reconstruct modelled carbon using synthetic observations consistent with current sampling programmes. Sensitivity tests show skill in reconstructing carbon trends and variability within the upper 2000 m. Our results indicate that this method can be used for a new global estimate for ocean carbon content.
Alexandre Mignot, Hervé Claustre, Gianpiero Cossarini, Fabrizio D'Ortenzio, Elodie Gutknecht, Julien Lamouroux, Paolo Lazzari, Coralie Perruche, Stefano Salon, Raphaëlle Sauzède, Vincent Taillandier, and Anna Teruzzi
Biogeosciences, 20, 1405–1422, https://doi.org/10.5194/bg-20-1405-2023, https://doi.org/10.5194/bg-20-1405-2023, 2023
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Numerical models of ocean biogeochemistry are becoming a major tool to detect and predict the impact of climate change on marine resources and monitor ocean health. Here, we demonstrate the use of the global array of BGC-Argo floats for the assessment of biogeochemical models. We first detail the handling of the BGC-Argo data set for model assessment purposes. We then present 23 assessment metrics to quantify the consistency of BGC model simulations with respect to BGC-Argo data.
Alban Planchat, Lester Kwiatkowski, Laurent Bopp, Olivier Torres, James R. Christian, Momme Butenschön, Tomas Lovato, Roland Séférian, Matthew A. Chamberlain, Olivier Aumont, Michio Watanabe, Akitomo Yamamoto, Andrew Yool, Tatiana Ilyina, Hiroyuki Tsujino, Kristen M. Krumhardt, Jörg Schwinger, Jerry Tjiputra, John P. Dunne, and Charles Stock
Biogeosciences, 20, 1195–1257, https://doi.org/10.5194/bg-20-1195-2023, https://doi.org/10.5194/bg-20-1195-2023, 2023
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Ocean alkalinity is critical to the uptake of atmospheric carbon and acidification in surface waters. We review the representation of alkalinity and the associated calcium carbonate cycle in Earth system models. While many parameterizations remain present in the latest generation of models, there is a general improvement in the simulated alkalinity distribution. This improvement is related to an increase in the export of biotic calcium carbonate, which closer resembles observations.
Jérôme Pinti, Tim DeVries, Tommy Norin, Camila Serra-Pompei, Roland Proud, David A. Siegel, Thomas Kiørboe, Colleen M. Petrik, Ken H. Andersen, Andrew S. Brierley, and André W. Visser
Biogeosciences, 20, 997–1009, https://doi.org/10.5194/bg-20-997-2023, https://doi.org/10.5194/bg-20-997-2023, 2023
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Large numbers of marine organisms such as zooplankton and fish perform daily vertical migration between the surface (at night) and the depths (in the daytime). This fascinating migration is important for the carbon cycle, as these organisms actively bring carbon to depths where it is stored away from the atmosphere for a long time. Here, we quantify the contributions of different animals to this carbon drawdown and storage and show that fish are important to the biological carbon pump.
Alastair J. M. Lough, Alessandro Tagliabue, Clément Demasy, Joseph A. Resing, Travis Mellett, Neil J. Wyatt, and Maeve C. Lohan
Biogeosciences, 20, 405–420, https://doi.org/10.5194/bg-20-405-2023, https://doi.org/10.5194/bg-20-405-2023, 2023
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Iron is a key nutrient for ocean primary productivity. Hydrothermal vents are a source of iron to the oceans, but the size of this source is poorly understood. This study examines the variability in iron inputs between hydrothermal vents in different geological settings. The vents studied release different amounts of Fe, resulting in plumes with similar dissolved iron concentrations but different particulate concentrations. This will help to refine modelling of iron-limited ocean productivity.
Nicole M. Travis, Colette L. Kelly, Margaret R. Mulholland, and Karen L. Casciotti
Biogeosciences, 20, 325–347, https://doi.org/10.5194/bg-20-325-2023, https://doi.org/10.5194/bg-20-325-2023, 2023
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The primary nitrite maximum is a ubiquitous upper ocean feature where nitrite accumulates, but we still do not understand its formation and the co-occurring microbial processes involved. Using correlative methods and rates measurements, we found strong spatial patterns between environmental conditions and depths of the nitrite maxima, but not the maximum concentrations. Nitrification was the dominant source of nitrite, with occasional high nitrite production from phytoplankton near the coast.
Natacha Le Grix, Jakob Zscheischler, Keith B. Rodgers, Ryohei Yamaguchi, and Thomas L. Frölicher
Biogeosciences, 19, 5807–5835, https://doi.org/10.5194/bg-19-5807-2022, https://doi.org/10.5194/bg-19-5807-2022, 2022
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Compound events threaten marine ecosystems. Here, we investigate the potentially harmful combination of marine heatwaves with low phytoplankton productivity. Using satellite-based observations, we show that these compound events are frequent in the low latitudes. We then investigate the drivers of these compound events using Earth system models. The models share similar drivers in the low latitudes but disagree in the high latitudes due to divergent factors limiting phytoplankton production.
Abigale M. Wyatt, Laure Resplandy, and Adrian Marchetti
Biogeosciences, 19, 5689–5705, https://doi.org/10.5194/bg-19-5689-2022, https://doi.org/10.5194/bg-19-5689-2022, 2022
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Marine heat waves (MHWs) are a frequent event in the northeast Pacific, with a large impact on the region's ecosystems. Large phytoplankton in the North Pacific Transition Zone are greatly affected by decreased nutrients, with less of an impact in the Alaskan Gyre. For small phytoplankton, MHWs increase the spring small phytoplankton population in both regions thanks to reduced light limitation. In both zones, this results in a significant decrease in the ratio of large to small phytoplankton.
Margot C. F. Debyser, Laetitia Pichevin, Robyn E. Tuerena, Paul A. Dodd, Antonia Doncila, and Raja S. Ganeshram
Biogeosciences, 19, 5499–5520, https://doi.org/10.5194/bg-19-5499-2022, https://doi.org/10.5194/bg-19-5499-2022, 2022
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We focus on the exchange of key nutrients for algae production between the Arctic and Atlantic oceans through the Fram Strait. We show that the export of dissolved silicon here is controlled by the availability of nitrate which is influenced by denitrification on Arctic shelves. We suggest that any future changes in the river inputs of silica and changes in denitrification due to climate change will impact the amount of silicon exported, with impacts on Atlantic algal productivity and ecology.
Emily J. Zakem, Barbara Bayer, Wei Qin, Alyson E. Santoro, Yao Zhang, and Naomi M. Levine
Biogeosciences, 19, 5401–5418, https://doi.org/10.5194/bg-19-5401-2022, https://doi.org/10.5194/bg-19-5401-2022, 2022
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We use a microbial ecosystem model to quantitatively explain the mechanisms controlling observed relative abundances and nitrification rates of ammonia- and nitrite-oxidizing microorganisms in the ocean. We also estimate how much global carbon fixation can be associated with chemoautotrophic nitrification. Our results improve our understanding of the controls on nitrification, laying the groundwork for more accurate predictions in global climate models.
Zuozhu Wen, Thomas J. Browning, Rongbo Dai, Wenwei Wu, Weiying Li, Xiaohua Hu, Wenfang Lin, Lifang Wang, Xin Liu, Zhimian Cao, Haizheng Hong, and Dalin Shi
Biogeosciences, 19, 5237–5250, https://doi.org/10.5194/bg-19-5237-2022, https://doi.org/10.5194/bg-19-5237-2022, 2022
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Fe and P are key factors controlling the biogeography and activity of marine N2-fixing microorganisms. We found lower abundance and activity of N2 fixers in the northern South China Sea than around the western boundary of the North Pacific, and N2 fixation rates switched from Fe–P co-limitation to P limitation. We hypothesize the Fe supply rates and Fe utilization strategies of each N2 fixer are important in regulating spatial variability in community structure across the study area.
Claudia Eisenring, Sophy E. Oliver, Samar Khatiwala, and Gregory F. de Souza
Biogeosciences, 19, 5079–5106, https://doi.org/10.5194/bg-19-5079-2022, https://doi.org/10.5194/bg-19-5079-2022, 2022
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Given the sparsity of observational constraints on micronutrients such as zinc (Zn), we assess the sensitivities of a framework for objective parameter optimisation in an oceanic Zn cycling model. Our ensemble of optimisations towards synthetic data with varying kinds of uncertainty shows that deficiencies related to model complexity and the choice of the misfit function generally have a greater impact on the retrieval of model Zn uptake behaviour than does the limitation of data coverage.
Yoshikazu Sasai, Sherwood Lan Smith, Eko Siswanto, Hideharu Sasaki, and Masami Nonaka
Biogeosciences, 19, 4865–4882, https://doi.org/10.5194/bg-19-4865-2022, https://doi.org/10.5194/bg-19-4865-2022, 2022
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We have investigated the adaptive response of phytoplankton growth to changing light, nutrients, and temperature over the North Pacific using two physical-biological models. We compare modeled chlorophyll and primary production from an inflexible control model (InFlexPFT), which assumes fixed carbon (C):nitrogen (N):chlorophyll (Chl) ratios, to a recently developed flexible phytoplankton functional type model (FlexPFT), which incorporates photoacclimation and variable C:N:Chl ratios.
Jens Terhaar, Thomas L. Frölicher, and Fortunat Joos
Biogeosciences, 19, 4431–4457, https://doi.org/10.5194/bg-19-4431-2022, https://doi.org/10.5194/bg-19-4431-2022, 2022
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Estimates of the ocean sink of anthropogenic carbon vary across various approaches. We show that the global ocean carbon sink can be estimated by three parameters, two of which approximate the ocean ventilation in the Southern Ocean and the North Atlantic, and one of which approximates the chemical capacity of the ocean to take up carbon. With observations of these parameters, we estimate that the global ocean carbon sink is 10 % larger than previously assumed, and we cut uncertainties in half.
Natasha René van Horsten, Hélène Planquette, Géraldine Sarthou, Thomas James Ryan-Keogh, Nolwenn Lemaitre, Thato Nicholas Mtshali, Alakendra Roychoudhury, and Eva Bucciarelli
Biogeosciences, 19, 3209–3224, https://doi.org/10.5194/bg-19-3209-2022, https://doi.org/10.5194/bg-19-3209-2022, 2022
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The remineralisation proxy, barite, was measured along 30°E in the southern Indian Ocean during early austral winter. To our knowledge this is the first reported Southern Ocean winter study. Concentrations throughout the water column were comparable to observations during spring to autumn. By linking satellite primary production to this proxy a possible annual timescale is proposed. These findings also suggest possible carbon remineralisation from satellite data on a basin scale.
Zhibo Shao and Ya-Wei Luo
Biogeosciences, 19, 2939–2952, https://doi.org/10.5194/bg-19-2939-2022, https://doi.org/10.5194/bg-19-2939-2022, 2022
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Non-cyanobacterial diazotrophs (NCDs) may be an important player in fixing N2 in the ocean. By conducting meta-analyses, we found that a representative marine NCD phylotype, Gamma A, tends to inhabit ocean environments with high productivity, low iron concentration and high light intensity. It also appears to be more abundant inside cyclonic eddies. Our study suggests a niche differentiation of NCDs from cyanobacterial diazotrophs as the latter prefers low-productivity and high-iron oceans.
Coraline Leseurre, Claire Lo Monaco, Gilles Reverdin, Nicolas Metzl, Jonathan Fin, Claude Mignon, and Léa Benito
Biogeosciences, 19, 2599–2625, https://doi.org/10.5194/bg-19-2599-2022, https://doi.org/10.5194/bg-19-2599-2022, 2022
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Decadal trends of fugacity of CO2 (fCO2), total alkalinity (AT), total carbon (CT) and pH in surface waters are investigated in different domains of the southern Indian Ocean (45°S–57°S) from ongoing and station observations regularly conducted in summer over the period 1998–2019. The fCO2 increase and pH decrease are mainly driven by anthropogenic CO2 estimated just below the summer mixed layer, as well as by a warming south of the polar front or in the fertilized waters near Kerguelen Island.
Priscilla Le Mézo, Jérôme Guiet, Kim Scherrer, Daniele Bianchi, and Eric Galbraith
Biogeosciences, 19, 2537–2555, https://doi.org/10.5194/bg-19-2537-2022, https://doi.org/10.5194/bg-19-2537-2022, 2022
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This study quantifies the role of commercially targeted fish biomass in the cycling of three important nutrients (N, P, and Fe), relative to nutrients otherwise available in water and to nutrients required by primary producers, and the impact of fishing. We use a model of commercially targeted fish biomass constrained by fish catch and stock assessment data to assess the contributions of fish at the global scale, at the time of the global peak catch and prior to industrial fishing.
Cited articles
Altabet, M. A. and Francois, R.: Sedimentary nitrogen isotopic ratio as a
recorder for surface ocean nitrate utilization, Global Biogeochem.
Cy., 8, 103–116, https://doi.org/10.1029/93gb03396, 1994.
Altieri, K. E., Fawcett, S. E., Peters, A. J., Sigman, D. M., and Hastings,
M. G.: Marine biogenic source of atmospheric organic nitrogen in the
subtropical North Atlantic, P. Natl. Acad. Sci. USA, 113, 925–930, https://doi.org/10.1073/pnas.1516847113,
2016.
Arrigo, K. R. and van Dijken, G. L.: Continued increases in Arctic Ocean
primary production, Prog. Oceanogr., 136, 60–70, https://doi.org/10.1016/j.pocean.2015.05.002, 2015.
Arthun, M., Ingvaldsen, R. B., Smedsrud, L. H., and Schrum, C.: Dense water
formation and circulation in the Barents Sea, Deep-Sea Res. Pt.
I, 58, 801–817, https://doi.org/10.1016/j.dsr.2011.06.001,
2011.
Arthun, M., Eldevik, T., Smedsrud, L. H., Skagseth, O., and Ingvaldsen, R.
B.: Quantifying the Influence of Atlantic Heat on Barents Sea Ice
Variability and Retreat, J. Climate, 25, 4736–4743, https://doi.org/10.1175/jcli-d-11-00466.1, 2012.
Barton, B. I., Lenn, Y. D., and Lique, C.: Observed Atlantification of the
Barents Sea Causes the Polar Front to Limit the Expansion of Winter Sea Ice,
J. Phys. Oceanogr., 48, 1849–1866, https://doi.org/10.1175/jpo-d-18-0003.1,
2018.
Brand, T., Norman, L., Henley, S. F., Mahaffey, C., and Tuerena, R.:
Dissolved nutrient samples collected in the Barents Sea as part
of the Changing Arctic Ocean programme for the Arctic PRIZE and ARISE
projects during cruise JR16006, British Oceanographic Data Centre, National Oceanography Centre, NERC, UK,
https://doi.org/10.5285/aed2abbb-9814-4a1be053-6c86abc04d55, 2020.
Brown, Z. W., Casciotti, K. L., Pickart, R. S., Swift, J. H., and Arrigo, K.
R.: Aspects of the marine nitrogen cycle of the Chukchi Sea shelf and Canada
Basin, Deep-Sea Res. Pt. II, 118,
73–87, https://doi.org/10.1016/j.dsr2.2015.02.009, 2015.
Buchwald, C., Santoro, A. E., McIlvin, M. R., and Casciotti, K. L.: Oxygen
isotopic composition of nitrate and nitrite produced by nitrifying
cocultures and natural marine assemblages, Limnol. Oceanogr., 57,
1361–1375, https://doi.org/10.4319/lo.2012.57.5.1361, 2012.
Casciotti, K. L., Sigman, D. M., Hastings, M. G., Bohlke, J. K., and
Hilkert, A.: Measurement of the oxygen isotopic composition of nitrate in
seawater and freshwater using the denitrifier method, Anal. Chem.,
74, 4905–4912, https://doi.org/10.1021/ac020113w, 2002.
Casciotti, K. L., Sigman, D. M., and Ward, B. B.: Linking diversity and
stable isotope fractionation in ammonia-oxidizing bacteria, Geomicrobiol.
J., 20, 335–353, https://doi.org/10.1080/01490450303895, 2003.
Chang, B. X. and Devol, A. H.: Seasonal and spatial patterns of sedimentary
denitrification rates in the Chukchi sea, Deep-Sea Res. Pt. II, 56, 1339–1350, https://doi.org/10.1016/j.dsr2.2008.10.024, 2009.
Christman, G. D., Cottrell, M. T., Popp, B. N., Gier, E., and Kirchman, D.
L.: Abundance, Diversity, and Activity of Ammonia-Oxidizing Prokaryotes in
the Coastal Arctic Ocean in Summer and Winter, Appl. Environ.
Microbiol., 77, 2026–2034, https://doi.org/10.1128/aem.01907-10, 2011.
Codispoti, L. A., Kelly, V., Thessen, A., Matrai, P., Suttles, S., Hill, V.,
Steele, M., and Light, B.: Synthesis of primary production in the Arctic
Ocean: III. Nitrate and phosphate based estimates of net community
production, Prog. Oceanogr., 110, 126–150, https://doi.org/10.1016/j.pocean.2012.11.006, 2013.
Coupel, P., Ruiz-Pino, D., Sicre, M. A., Chen, J. F., Lee, S. H.,
Schiffrine, N., Li, H. L., and Gascard, J. C.: The impact of freshening on
phytoplankton production in the Pacific Arctic Ocean, Prog.
Oceanogr., 131, 113–125, https://doi.org/10.1016/j.pocean.2014.12.003, 2015.
Dalpadado, P., Arrigo, K. R., Hjollo, S. S., Rey, F., Ingvaldsen, R. B.,
Sperfeld, E., van Dijken, G. L., Stige, L. C., Olsen, A., and Ottersen, G.:
Productivity in the Barents Sea – Response to Recent Climate Variability,
Plos One, 9, e95273,
https://doi.org/10.1371/journal.pone.0095273, 2014.
de la Vega, C., Mahaffey, C., Tuerena, R. E., Yurkowski, D. J., Ferguson, S.
H., Stenson, G. B., Nordoy, E. S., Haug, T., Biuw, M., Smout, S., Hopkins,
J. Tagliabue, A., and Jeffreys, R. M.: Arctic seals as tracers of
environmental and ecological change, Limnol. Oceanogr. Lett., https://doi.org/10.1002/lol2.10176, online first, 2020.
DiFiore, P. J., Sigman, D. M., Trull, T. W., Lourey, M. J., Karsh, K., Cane,
G., and Ho, R.: Nitrogen isotope constraints on subantarctic
biogeochemistry, J. Geophys. Res.-Oceans, 111, C08016,
https://doi.org/10.1029/2005jc003216, 2006.
DiFiore, P. J., Sigman, D. M., and Dunbar, R. B.: Upper ocean nitrogen
fluxes in the Polar Antarctic Zone: Constraints from the nitrogen and oxygen
isotopes of nitrate, Geochem. Geophys. Geosy., 10, Q11016,
https://doi.org/10.1029/2009gc002468, 2009.
DiFiore, P. J., Sigman, D. M., Karsh, K. L., Trull, T. W., Dunbar, R. B.,
and Robinson, R. S.: Poleward decrease in the isotope
effect of nitrate assimilation across the Southern Ocean, Geophys.
Res. Lett., 37, L17601,
https://doi.org/10.1029/2010gl044090, 2010.
Dumont, E., Brand, T., and Hopkins, J.: CTD data from NERC Changing Arctic Ocean Cruise
JR16006 on the RRS James Clark Ross, June–August 2017, British
Oceanographic Data Centre, National Oceanography Centre, NERC, UK, https://doi.org/10/c7f6, 2019.
Ellingsen, I., Slagstad, D., and Sundfjord, A.: Modification of water masses
in the Barents Sea and its coupling to ice dynamics: a model study, Ocean
Dyn., 59, 1095–1108, https://doi.org/10.1007/s10236-009-0230-5, 2009.
Fawcett, S. E., Lomas, M., Casey, J. R., Ward, B. B., and Sigman, D. M.:
Assimilation of upwelled nitrate by small eukaryotes in the
Sargasso Sea, Nat. Geosci., 4, 717–722, https://doi.org/10.1038/ngeo1265, 2011.
Fawcett, S. E., Lomas, M. W., Ward, B. B., and Sigman, D. M.: The
counterintuitive effect of summer-to-fall mixed layer deepening on
eukaryotic new production in the Sargasso Sea, Global Biogeochem. Cy.,
28, 86–102, https://doi.org/10.1002/2013gb004579, 2014.
Friedland, K. D. and Todd, C. D.: Changes in Northwest Atlantic Arctic and
Subarctic conditions and the growth response of Atlantic salmon, Polar
Biol., 35, 593–609, https://doi.org/10.1007/s00300-011-1105-z, 2012.
Fripiat, F., Declercq, M., Sapart, C. J., Anderson, L. G., Bruechert, V.,
Deman, F., Fonseca-Batista, D., Humborg, C., Roukaerts, A., Semiletov, I.
P., and Dehairs, F.: Influence of the bordering shelves on nutrient
distribution in the Arctic halocline inferred from water column nitrate
isotopes, Limnol. Oceanogr., 63, 2154–2170, https://doi.org/10.1002/lno.10930,
2018.
Granger, J. and Sigman, D. M.: Removal of nitrite with sulfamic acid for
nitrate N and O isotope analysis with the denitrifier method, Rapid
Commun. Mass Spectr., 23, 3753–3762, https://doi.org/10.1002/rcm.4307, 2009.
Granger, J., Sigman, D. M., Needoba, J. A., and Harrison, P. J.: Coupled
nitrogen and oxygen isotope fractionation of nitrate during assimilation by
cultures of marine phytoplankton, Limnol. Oceanogr., 49, 1763–1773,
2004.
Granger, J., Prokopenko, M. G., Sigman, D. M., Mordy, C. W., Morse, Z. M.,
Morales, L. V., Sambrotto, R. N., and Plessen, B.: Coupled
nitrification-denitrification in sediment of the eastern Bering Sea shelf
leads to N-15 enrichment of fixed N in shelf waters, J. Geophys.
Res.-Oceans, 116, C11006, https://doi.org/10.1029/2010jc006751, 2011.
Granger, J., Prokopenko, M. G., Mordy, C. W., and Sigman, D. M.: The
proportion of remineralized nitrate on the ice-covered eastern Bering Sea
shelf evidenced from the oxygen isotope ratio of nitrate, Global
Biogeochem. Cy., 27, 962–971, https://doi.org/10.1002/gbc.20075, 2013.
Granger, J., Sigman, D. M., Gagnon, J., Tremblay, J. E., and Mucci, A.: On
the Properties of the Arctic Halocline and Deep Water Masses of the Canada
Basin from Nitrate Isotope Ratios, J. Geophys. Res.-Oceans,
123, 5443–5458, https://doi.org/10.1029/2018jc014110, 2018.
Hatun, H., Azetsu-Scott, K., Somavilla, R., Rey, F., Johnson, C., Mathis,
M., Mikolajewicz, U., CoupeI, P., Tremblay, J. E., Hartman, S., Pacariz, S.
V., Salter, I., and Olafsson, J.: The subpolar gyre regulates silicate
concentrations in the North Atlantic, Sci. Rep., 7, 14576,
https://doi.org/10.1038/s41598-017-14837-4, 2017.
Henley, S. F., Porter, M., Hobbs, L., Braun, J., Guillaume-Castel, R.,
Venables, E. J., Dumont, E., and Cottier, F.: Nitrate supply
and uptake in the Atlantic Arctic sea ice zone: seasonal cycle, mechanisms
and drivers, Philos. T. Roy. Soc. A.,
378, 2181, https://doi.org/10.1098/rsta.2019.0361, 2020.
Henley, S. F., Tuerena, R. E., Annett, A. L., Fallick, A. E., Meredith, M.
P., Venables, H. J., Clarke, A., and Ganeshram, R. S.:
Macronutrient supply, uptake and recycling in the coastal ocean of the west
Antarctic Peninsula, Deep-Sea Res. Pt. II, 139, 58–76, https://doi.org/10.1016/j.dsr2.2016.10.003, 2017.
Huang, J. B., Zhang, X. D., Zhang, Q. Y., Lin, Y. L., Hao, M. J., Luo, Y.,
Zhao, Z. C., Yao, Y., Chen, X., Wang, L., Nie, S. P., Yin, Y. Z., Xu, Y.,
and Zhang, J. S.: Recently amplified arctic warming has contributed to a
continual global warming trend, Nat. Clim. Change, 7, 875–879,
https://doi.org/10.1038/s41558-017-0009-5, 2017.
Johnson, C., Inall, M., and Hakkinen, S.: Declining nutrient concentrations
in the northeast Atlantic as a result of a weakening Subpolar Gyre, Deep-Sea
Res. Pt. I, 82, 95–107, https://doi.org/10.1016/j.dsr.2013.08.007, 2013.
Kemeny, P. C., Weigand, M. A., Zhang, R., Carter, B. R., Karsh, K. L.,
Fawcett, S. E., and Sigman, D. M.: Enzyme-level interconversion of nitrate
and nitrite in the fall mixed layer of the Antarctic Ocean, Global
Biogeochem. Cy., 30, 1069–1085, https://doi.org/10.1002/2015gb005350, 2016.
Knapp, A. N., DiFiore, P. J., Deutsch, C., Sigman, D. M., and Lipschultz,
F.: Nitrate isotopic composition between Bermuda and Puerto Rico:
Implications for N(2) fixation in the Atlantic Ocean, Global Biogeochem.
Cy., 22, Gb3014, https://doi.org/10.1029/2007gb003107, 2008.
Knapp, A. N., Fawcett, S. E., Martínez-Garcia, A., Leblond, N., Moutin, T., and Bonnet, S.: Nitrogen isotopic evidence for a shift from nitrate- to diazotroph-fueled export production in the VAHINE mesocosm experiments, Biogeosciences, 13, 4645–4657, https://doi.org/10.5194/bg-13-4645-2016, 2016.
Lehmann, M. F., Sigman, D. M., McCorkle, D. C., Granger, J., Hoffmann, S.,
Cane, G., and Brunelle, B. G.: The distribution of nitrate N-15/N-14 in
marine sediments and the impact of benthic nitrogen loss on the isotopic
composition of oceanic nitrate, Geochim. Cosmochim. Ac., 71,
5384–5404, https://doi.org/10.1016/j.gca.2007.07.025, 2007.
Lewis, K. M., Van Dijken, G. L., and Arrigo, K. R.: Changes in phytoplankton
concentration now drive increased Arctic Ocean primary production, Science,
369,
198–202, https://doi.org/10.1126/science.aay8380, 2020.
Lind, S., Ingvaldsen, R. B., and Furevik, T.: Arctic layer salinity controls
heat loss from deep Atlantic layer in seasonally ice-covered areas of the
Barents Sea, Geophys. Res. Lett., 43, 5233–5242, https://doi.org/10.1002/2016gl068421, 2016.
Lind, S., Ingvaldsen, R. B., and Furevik, T.: Arctic warming hotspot in the
northern Barents Sea linked to declining sea-ice import, Nat. Clim.
Change, 8, 634–639, https://doi.org/10.1038/s41558-018-0205-y, 2018.
Marconi, D., Weigand, M. A., Rafter, P. A., McIlvin, M. R., Forbes, M.,
Casciotti, K. L., and Sigman, D. M.: Nitrate isotope distributions on the US
GEOTRACES North Atlantic cross-basin section: Signals of polar nitrate
sources and low latitude nitrogen cycling, Mar. Chem., 177, 143–156, https://doi.org/10.1016/j.marchem.2015.06.007, 2015.
Marconi, D., Sigman, D. M., Casciotti, K. L., Campbell, E. C., Weigand, M.
A., Fawcett, S. E., Knapp, A. N., Rafter, P. A., Ward, B. B., and Haug, G.
H.: Tropical Dominance of N-2 Fixation in the North Atlantic Ocean, Global
Biogeochem. Cy., 31, 1608–1623, https://doi.org/10.1002/2016gb005613, 2017.
Mariotti, A., Germon, J. C., Hubert, P., Kaiser, P., Letolle, R., Tardieux,
A., and Tardieux, P.: Experimental – determination of nitrogen kinetic
isotope fractionation – some principles – Illustration for the
denitrification and nitrification processes, Plant Soil, 62, 413–430, https://doi.org/10.1007/bf02374138, 1981.
Mills, M. M., Brown, Z. W., Laney, S. R., Ortega-Retuerta, E., Lowry, K. E.,
van Dijken, G. L., and Arrigo, K. R.: Nitrogen Limitation of the Summer
Phytoplankton and Heterotrophic Prokaryote Communities in the Chukchi Sea,
Front. Marine Sci., 5, 362, https://doi.org/10.3389/fmars.2018.00362, 2018.
Norman, L., de la Vega, C., Ball, J., and Mahaffey, C.: δ15N-PN, δ13C-PC, particulate organic nitrogen and particulate organic carbon
measurements from CTD niskin-collected water column profiles obtained in the
Barents Sea during NERC CAO cruise JR16006, July–August 2017, British
Oceanographic Data Centre, National Oceanography Centre, NERC, UK,
https://doi.org/10/fkg8, 2020.
Notz, D. and Stroeve, J.: Observed Arctic sea-ice loss directly follows
anthropogenic CO2 emission, Science, 354, 747–750, https://doi.org/10.1126/science.aag2345,
2016.
Onarheim, I. H. and Arthun, M.: Toward an ice-free Barents Sea, Geophys.
Res. Lett., 44, 8387–8395, https://doi.org/10.1002/2017gl074304, 2017.
Onarheim, I. H., Eldevik, T., Arthun, M., Ingvaldsen, R. B., and Smedsrud,
L. H.: Skillful prediction of Barents Sea ice cover, Geophys. Res.
Lett., 42, 5364–5371, https://doi.org/10.1002/2015gl064359, 2015.
Oziel, L., Sirven, J., and Gascard, J.-C.: The Barents Sea frontal zones and water masses variability (1980–2011), Ocean Sci., 12, 169–184, https://doi.org/10.5194/os-12-169-2016, 2016.
Oziel, L., Baudena, A., Ardyna, M., Massicotte, P., Randelhoff, A.,
Sallée, J. B., Ingvaldsen, R. B., Devred, E., and Babin, M.: Faster
Atlantic currents drive poleward expansion of temperate phytoplankton in the
Arctic Ocean, Nat. Commun., 11, 1705,
https://doi.org/10.1038/s41467-020-15485-5, 2020.
Peng, X. F., Fawcett, S. E., van Oostende, N., Wolf, M. J., Marconi, D.,
Sigman, D. M., and Ward, B. B.: Nitrogen uptake and nitrification in the
subarctic North Atlantic Ocean, Limnol. Oceanogr., 63, 1462–1487, https://doi.org/10.1002/lno.10784, 2018.
Porter, M., Henley, S. F., Orkney, A., Bouman, H. A., Hwang, B., Dumont, E.,
Venables, E. J., and Cottier, F.: A Polar Surface
Eddy Obscured by Thermal Stratification, Geophys. Res. Lett.,
47, e2019GL086281, https://doi.org/10.1029/2019gl086281, 2020.
Rafter, P. A., Sigman, D. M., Charles, C. D., Kaiser, J., and Haug, G. H.:
Subsurface tropical Pacific nitrogen isotopic composition of nitrate:
Biogeochemical signals and their transport, Global Biogeochem. Cy.,
26, GB1003,
https://doi.org/10.1029/2010gb003979, 2012.
Rafter, P. A., DiFiore, P. J., and Sigman, D. M.: Coupled nitrate nitrogen
and oxygen isotopes and organic matter remineralization in the Southern and
Pacific Oceans, J. Geophys. Res.-Oceans, 118, 4781–4794, https://doi.org/10.1002/jgrc.20316, 2013.
Randelhoff, A., Reigstad, M., Chierici, M., Sundfjord, A., Ivanov, V., Cape,
M., Vernet, M., Tremblay, J. E., Bratbak, G., and Kristiansen, S.
Seasonality of the Physical and Biogeochemical Hydrography in
the Inflow to the Arctic Ocean Through Fram Strait,
Front. Mar. Sci. 5, 224,
https://doi.org/10.3389/fmars.2018.00224, 2018.
Rey, F.: Declining silicate concentrations in the Norwegian and Barents
Seas, Ices Journal of Marine Science, 69, 208–212, https://doi.org/10.1093/icesjms/fss007,
2012.
Rudels, B., Anderson, L. G., and Jones, E. P.: Formation and evolution of
the surface mixed layer and halocline of the Arctic Ocean, J.
Geophys. Res.-Oceans, 101, 8807–8821, https://doi.org/10.1029/96jc00143, 1996.
Schauer, U., Muench, R. D., Rudels, B., and Timokhov, L.: Impact of eastern Arctic shelf waters on the Nansen Basin intermediate layers, J. Geophys. Res., 102, 3371–3382, https://doi.org/10.1029/96JC03366, 1997.
Serreze, M. C., Barrett, A. P., Stroeve, J. C., Kindig, D. N., and Holland, M. M.: The emergence of surface-based Arctic amplification, The Cryosphere, 3, 11–19, https://doi.org/10.5194/tc-3-11-2009, 2009.
Sigman, D. M., Altabet, M. A., McCorkle, D. C., Francois, R., and Fischer,
G.: The delta N-15 of nitrate in the Southern Ocean: Consumption of nitrate
in surface waters, Global Biogeochem. Cy., 13, 1149–1166, https://doi.org/10.1029/1999gb900038, 1999.
Sigman, D. M., Altabet, M. A., McCorkle, D. C., Francois, R., and Fischer,
G.: The delta N-15 of nitrate in the Southern Ocean: Nitrogen cycling and
circulation in the ocean interior, J. Geophys. Res.-Oceans,
105, 19599–19614, https://doi.org/10.1029/2000jc000265, 2000.
Sigman, D. M., Casciotti, K. L., Andreani, M., Barford, C., Galanter, M.,
and Bohlke, J. K.: A bacterial method for the nitrogen isotopic analysis of
nitrate in seawater and freshwater, Anal. Chem., 73, 4145–4153, https://doi.org/10.1021/ac010088e, 2001.
Sigman, D. M., Robinson, R., Knapp, A. N., van Geen, A., McCorkle, D. C.,
Brandes, J. A., and Thunell, R. C.: Distinguishing between water column and
sedimentary denitrification in the Santa Barbara Basin using the stable
isotopes of nitrate, Geochem. Geophy. Geosy., 4, 1040,
https://doi.org/10.1029/2002gc000384, 2003.
Sigman, D. M., DiFiore, P. J., Hain, M. P., Deutsch, C., and Karl, D. M.:
Sinking organic matter spreads the nitrogen isotope signal of pelagic
denitrification in the North Pacific, Geophys. Res. Lett., 36,
L08605, https://doi.org/10.1029/2008gl035784, 2009a.
Sigman, D. M., DiFiore, P. J., Hain, M. P., Deutsch, C., Wang, Y., Karl, D.
M., Knapp, A. N., Lehmann, M. F., and Pantoja, S.: The dual isotopes of deep
nitrate as a constraint on the cycle and budget of oceanic fixed nitrogen,
Deep-Sea Res. Pt. I, 56, 1419–1439, https://doi.org/10.1016/j.dsr.2009.04.007, 2009b.
Smedsrud, L. H., Esau, I., Ingvaldsen, R. B., Eldevik, T., Haugan, P. M.,
Li, C., Lien, V. S., Olsen, A., Omar, A. M., Ottera, O. H., Risebrobakken,
B., Sando, A. B., Semenov, V. A., and Sorokina, S. A.: The role of the
Barents Sea in the Arctic climate system, Rev. Geophys., 51,
415–449, https://doi.org/10.1002/rog.20017, 2013.
Sundfjord, A., Fer, I., Kasajima, Y., and Svendsen, H.: Observations of
turbulent mixing and hydrography in the marginal ice zone of the Barents
Sea, J. Geophys. Res.-Oceans, 112, C05008,
https://doi.org/10.1029/2006jc003524,
2007.
Thibodeau, B., Bauch, D., and Voss, M.: Nitrogen dynamic in Eurasian coastal
Arctic ecosystem: Insight from nitrogen isotope, Global Biogeochem.
Cy., 31, 836–849, https://doi.org/10.1002/2016gb005593, 2017.
Torres-Valdes, S., Tsubouchi, T., Bacon, S., Naveira-Garabato, A. C.,
Sanders, R., McLaughlin, F. A., Petrie, B., Kattner, G., Azetsu-Scott, K.,
and Whitledge, T. E.: Export of nutrients from the Arctic Ocean, J.
Geophys. Res.-Oceans, 118, 1625–1644, https://doi.org/10.1002/jgrc.20063, 2013.
Tuerena R. and Ganeshram R.: Nitrate isotope measurements from CTD niskin depth
profiles from Changing Arctic Ocean cruise JR16006 in the Barents Sea during
summer 2017, British Oceanographic Data Centre, National Oceanography
Centre, NERC, UK, https://doi.org/10/fg27, 2020.
Tuerena, R. E., Ganeshram, R. S., Geibert, W., Fallick, A. E., Dougans, J.,
Tait, A., Henley, S. F., and Woodward, E. M. S.: Nutrient cycling in the
Atlantic basin: The evolution of nitrate isotope signatures in water masses,
Global Biogeochem. Cy., 29, 1830–1844, https://doi.org/10.1002/2015gb005164, 2015.
Vage, S., Basedow, S. L., Tande, K. S., and Zhou, M.: Physical structure of
the Barents Sea Polar Front near Storbanken in August 2007, J.
Marine Syst., 130, 256–262, https://doi.org/10.1016/j.jmarsys.2011.11.019, 2014.
Van Oostende, N., Fawcett, S. E., Marconi, D., Lueders-Dumont, J., Sabadel,
A. J. M., Woodward, E. M. S., Jonsson, B. F., Sigman, D. M., and Ward, B.
B.: Variation of summer phytoplankton community composition and its
relationship to nitrate and regenerated nitrogen assimilation across the
North Atlantic Ocean, Deep-Sea Res. Pt. I, 121, 79–94, https://doi.org/10.1016/j.dsr.2016.12.012, 2017.
Weigand, M. A., Foriel, J., Barnett, B., Oleynik, S., and Sigman, D. M.:
Updates to instrumentation and protocols for isotopic analysis of nitrate by
the denitrifier method, Rapid Commun. Mass Spectrom., 30,
1365–1383, https://doi.org/10.1002/rcm.7570, 2016.
Woodgate, R. A.: Increases in the Pacific inflow to the Arctic from 1990 to
2015, and insights into seasonal trends and driving mechanisms from
year-round Bering Strait mooring data, Prog. Oceanogr., 160,
124–154, https://doi.org/10.1016/j.pocean.2017.12.007, 2018.
Short summary
The Barents Sea is a rapidly changing shallow sea within the Arctic. Here, nitrate, an essential nutrient, is fully consumed by algae in surface waters during summer months. Nitrate is efficiently regenerated in the Barents Sea, and there is no evidence for nitrogen loss from the sediments by denitrification, which is prevalent on other Arctic shelves. This suggests that nitrogen availability in the Barents Sea is largely determined by the supply of nutrients in water masses from the Atlantic.
The Barents Sea is a rapidly changing shallow sea within the Arctic. Here, nitrate, an...
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