Articles | Volume 17, issue 10
https://doi.org/10.5194/bg-17-2875-2020
© Author(s) 2020. 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-17-2875-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
29 May 2020
Research article |
| 29 May 2020
| 29 May 2020
Wind-driven stratification patterns and dissolved oxygen depletion off the Changjiang (Yangtze) Estuary
Taavi Liblik
State Key Laboratory of Marine Geology, Tongji University, Shanghai,
200092, China
Department of Marine Systems, Tallinn University of Technology,
Tallinn, 12618, Estonia
Yijing Wu
State Key Laboratory of Marine Geology, Tongji University, Shanghai,
200092, China
Daidu Fan
CORRESPONDING AUTHOR
State Key Laboratory of Marine Geology, Tongji University, Shanghai,
200092, China
Laboratory of Marine Geology, Qingdao National Laboratory for Marine
Science and Technology, 387P+WW Shinan, Qingdao, Shandong, China
Dinghui Shang
State Key Laboratory of Marine Geology, Tongji University, Shanghai,
200092, China
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Kai Salm, Germo Väli, Taavi Liblik, and Urmas Lips
EGUsphere, https://doi.org/10.5194/egusphere-2024-4082, https://doi.org/10.5194/egusphere-2024-4082, 2025
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We show that forcing-dependent presence of submesoscale processes is detected by glider observations and high-resolution numerical simulation. Peak of submesoscale variations was observed at the base of the upper mixed layer in spring and in the thermocline in summer. Coastal upwellings and topography-related instabilities of frontal currents were the likely drivers of submesoscale processes and subduction that transport surface waters and tracers below the thermocline.
Taavi Liblik, Daniel Rak, Enriko Siht, Germo Väli, Johannes Karstensen, Laura Tuomi, Louise C. Biddle, Madis-Jaak Lilover, Māris Skudra, Michael Naumann, Urmas Lips, and Volker Mohrholz
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Eight current meters were deployed to the seafloor across the Baltic to enhance knowledge about circulation and currents. The experiment was complemented by autonomous vehicles. Stable circulation patterns were observed at the sea when weather was steady. Strong and quite persistent currents were observed at the key passage for the deep-water renewal of the Northern Baltic Sea. Deep water renewal mostly occurs during spring and summer periods in the northern Baltic Sea.
Stella-Theresa Stoicescu, Jaan Laanemets, Taavi Liblik, Māris Skudra, Oliver Samlas, Inga Lips, and Urmas Lips
Biogeosciences, 19, 2903–2920, https://doi.org/10.5194/bg-19-2903-2022, https://doi.org/10.5194/bg-19-2903-2022, 2022
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Coastal basins with high input of nutrients often suffer from oxygen deficiency. In summer 2018, the extent of oxygen depletion was exceptional in the Gulf of Riga. We analyzed observational data and found that extensive oxygen deficiency appeared since the water layer close to the seabed, where oxygen is consumed, was separated from the surface layer. The problem worsens if similar conditions restricting vertical transport of oxygen occur more frequently in the future.
Taavi Liblik, Germo Väli, Kai Salm, Jaan Laanemets, Madis-Jaak Lilover, and Urmas Lips
Ocean Sci., 18, 857–879, https://doi.org/10.5194/os-18-857-2022, https://doi.org/10.5194/os-18-857-2022, 2022
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An extensive measurement campaign and numerical simulations were conducted in the central Baltic Sea. The persistent circulation patterns were detected in steady weather conditions. The patterns included various circulation features. A coastal boundary current was observed along the eastern coast. The deep layer current towards the north was detected as well. This current is an important deeper limb of the overturning circulation of the Baltic Sea. The circulation regime has an annual cycle.
Andreas Lehmann, Kai Myrberg, Piia Post, Irina Chubarenko, Inga Dailidiene, Hans-Harald Hinrichsen, Karin Hüssy, Taavi Liblik, H. E. Markus Meier, Urmas Lips, and Tatiana Bukanova
Earth Syst. Dynam., 13, 373–392, https://doi.org/10.5194/esd-13-373-2022, https://doi.org/10.5194/esd-13-373-2022, 2022
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The salinity in the Baltic Sea is not only an important topic for physical oceanography as such, but it also integrates the complete water and energy cycle. It is a primary external driver controlling ecosystem dynamics of the Baltic Sea. The long-term dynamics are controlled by river runoff, net precipitation, and the water mass exchange between the North Sea and Baltic Sea. On shorter timescales, the ephemeral atmospheric conditions drive a very complex and highly variable salinity regime.
Taavi Liblik, Germo Väli, Inga Lips, Madis-Jaak Lilover, Villu Kikas, and Jaan Laanemets
Ocean Sci., 16, 1475–1490, https://doi.org/10.5194/os-16-1475-2020, https://doi.org/10.5194/os-16-1475-2020, 2020
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The upper mixed layer, shallower than the depth of the euphotic zone, is one of the preconditions for enhanced primary production in the ocean. In the Baltic Sea, the general understanding is that the upper mixed layer is much deeper in winter. In this study, we demonstrate that wintertime shallow stratification and an elevated phytoplankton biomass proxy, chlorophyll, are common in the Gulf of Finland. Stratification is invoked by the westward flow of riverine water forced by an easterly wind.
Sergey R. Chalov, Victor Ivanov, Danila Shkolnyi, Ekaterina Pavlyukevich, Michal Habel, Dmitry Botavin, Aleksandra Chalova, Pavel Golovlev, Arseny Kamyshev, Roman Kolesnikov, Uliana Koneva, Anna Kurakova, Nadezda Mikhailova, Elizaveta Tuzova, Kristina Prokopeva, Aleksandr Zavadsky, Rituparna Acharyya, Roman S. Chalov, Aleksandr Varenov, Leonid Turykin, Anna Tarbeeva, and Daidu Fan
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-150, https://doi.org/10.5194/essd-2025-150, 2025
Preprint under review for ESSD
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This study presents a unique multi-tool dataset on riverbank migration across Northern Eurasia, covering 140,000 km of river channels over a period of up to 70 years. Using satellite imagery and field observations, we identify key drivers of bank erosion in large spatial scale and highlight role of river discharge and permafrost. The dataset enhances understanding of river channel dynamics and supports the development of predictive models for river channel evolution and erosion risk assessment.
Kai Salm, Germo Väli, Taavi Liblik, and Urmas Lips
EGUsphere, https://doi.org/10.5194/egusphere-2024-4082, https://doi.org/10.5194/egusphere-2024-4082, 2025
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We show that forcing-dependent presence of submesoscale processes is detected by glider observations and high-resolution numerical simulation. Peak of submesoscale variations was observed at the base of the upper mixed layer in spring and in the thermocline in summer. Coastal upwellings and topography-related instabilities of frontal currents were the likely drivers of submesoscale processes and subduction that transport surface waters and tracers below the thermocline.
Taavi Liblik, Daniel Rak, Enriko Siht, Germo Väli, Johannes Karstensen, Laura Tuomi, Louise C. Biddle, Madis-Jaak Lilover, Māris Skudra, Michael Naumann, Urmas Lips, and Volker Mohrholz
EGUsphere, https://doi.org/10.5194/egusphere-2024-2272, https://doi.org/10.5194/egusphere-2024-2272, 2024
Preprint archived
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Eight current meters were deployed to the seafloor across the Baltic to enhance knowledge about circulation and currents. The experiment was complemented by autonomous vehicles. Stable circulation patterns were observed at the sea when weather was steady. Strong and quite persistent currents were observed at the key passage for the deep-water renewal of the Northern Baltic Sea. Deep water renewal mostly occurs during spring and summer periods in the northern Baltic Sea.
Stella-Theresa Stoicescu, Jaan Laanemets, Taavi Liblik, Māris Skudra, Oliver Samlas, Inga Lips, and Urmas Lips
Biogeosciences, 19, 2903–2920, https://doi.org/10.5194/bg-19-2903-2022, https://doi.org/10.5194/bg-19-2903-2022, 2022
Short summary
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Coastal basins with high input of nutrients often suffer from oxygen deficiency. In summer 2018, the extent of oxygen depletion was exceptional in the Gulf of Riga. We analyzed observational data and found that extensive oxygen deficiency appeared since the water layer close to the seabed, where oxygen is consumed, was separated from the surface layer. The problem worsens if similar conditions restricting vertical transport of oxygen occur more frequently in the future.
Taavi Liblik, Germo Väli, Kai Salm, Jaan Laanemets, Madis-Jaak Lilover, and Urmas Lips
Ocean Sci., 18, 857–879, https://doi.org/10.5194/os-18-857-2022, https://doi.org/10.5194/os-18-857-2022, 2022
Short summary
Short summary
An extensive measurement campaign and numerical simulations were conducted in the central Baltic Sea. The persistent circulation patterns were detected in steady weather conditions. The patterns included various circulation features. A coastal boundary current was observed along the eastern coast. The deep layer current towards the north was detected as well. This current is an important deeper limb of the overturning circulation of the Baltic Sea. The circulation regime has an annual cycle.
Andreas Lehmann, Kai Myrberg, Piia Post, Irina Chubarenko, Inga Dailidiene, Hans-Harald Hinrichsen, Karin Hüssy, Taavi Liblik, H. E. Markus Meier, Urmas Lips, and Tatiana Bukanova
Earth Syst. Dynam., 13, 373–392, https://doi.org/10.5194/esd-13-373-2022, https://doi.org/10.5194/esd-13-373-2022, 2022
Short summary
Short summary
The salinity in the Baltic Sea is not only an important topic for physical oceanography as such, but it also integrates the complete water and energy cycle. It is a primary external driver controlling ecosystem dynamics of the Baltic Sea. The long-term dynamics are controlled by river runoff, net precipitation, and the water mass exchange between the North Sea and Baltic Sea. On shorter timescales, the ephemeral atmospheric conditions drive a very complex and highly variable salinity regime.
Taavi Liblik, Germo Väli, Inga Lips, Madis-Jaak Lilover, Villu Kikas, and Jaan Laanemets
Ocean Sci., 16, 1475–1490, https://doi.org/10.5194/os-16-1475-2020, https://doi.org/10.5194/os-16-1475-2020, 2020
Short summary
Short summary
The upper mixed layer, shallower than the depth of the euphotic zone, is one of the preconditions for enhanced primary production in the ocean. In the Baltic Sea, the general understanding is that the upper mixed layer is much deeper in winter. In this study, we demonstrate that wintertime shallow stratification and an elevated phytoplankton biomass proxy, chlorophyll, are common in the Gulf of Finland. Stratification is invoked by the westward flow of riverine water forced by an easterly wind.
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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.
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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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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.
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.
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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.
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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.
Vlad A. Macovei, Louise C. V. Rewrie, Rüdiger Röttgers, and Yoana G. Voynova
EGUsphere, https://doi.org/10.5194/egusphere-2024-2643, https://doi.org/10.5194/egusphere-2024-2643, 2024
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A commercial vessel equipped with scientific instruments regularly travelled between two large macro-tidal estuaries. We found that biogeochemical variability in the outer estuaries is driven by the 14-day spring-neap tidal cycle, with strong effects on dissolved inorganic and organic carbon concentrations and distribution. Since this land-sea interface effect increases the strength of the carbon source to the atmosphere by 74 % during spring tide, it should be accounted for in regional models.
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.
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
EGUsphere, https://doi.org/10.5194/egusphere-2024-1632, https://doi.org/10.5194/egusphere-2024-1632, 2024
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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 pore-water dataset 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.
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.
Darren Pilcher, Jessica Cross, Natalie Monacci, Linquan Mu, Kelly Kearney, Albert Hermann, and Wei Cheng
EGUsphere, https://doi.org/10.5194/egusphere-2024-1096, https://doi.org/10.5194/egusphere-2024-1096, 2024
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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.
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.
K. Mareike Paul, Martijn Hermans, Sami A. Jokinen, Inda Brinkmann, Helena L. Filipsson, and Tom Jilbert
Biogeosciences, 20, 5003–5028, https://doi.org/10.5194/bg-20-5003-2023, https://doi.org/10.5194/bg-20-5003-2023, 2023
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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.
Hannah Sharpe, Michel Gosselin, Catherine Lalande, Alexandre Normandeau, Jean-Carlos Montero-Serrano, Khouloud Baccara, Daniel Bourgault, Owen Sherwood, and Audrey Limoges
Biogeosciences, 20, 4981–5001, https://doi.org/10.5194/bg-20-4981-2023, https://doi.org/10.5194/bg-20-4981-2023, 2023
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We studied the impact of submarine canyon processes within the Pointe-des-Monts system on biogenic matter export and phytoplankton assemblages. Using data from three oceanographic moorings, we show that the canyon experienced two low-amplitude sediment remobilization events in 2020–2021 that led to enhanced particle fluxes in the deep-water column layer > 2.6 km offshore. Sinking phytoplankton fluxes were lower near the canyon compared to background values from the lower St. Lawrence Estuary.
Dewi Langlet, Florian Mermillod-Blondin, Noémie Deldicq, Arthur Bauville, Gwendoline Duong, Lara Konecny, Mylène Hugoni, Lionel Denis, and Vincent M. P. Bouchet
Biogeosciences, 20, 4875–4891, https://doi.org/10.5194/bg-20-4875-2023, https://doi.org/10.5194/bg-20-4875-2023, 2023
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Benthic foraminifera are single-cell marine organisms which can move in the sediment column. They were previously reported to horizontally and vertically transport sediment particles, yet the impact of their motion on the dissolved fluxes remains unknown. Using microprofiling, we show here that foraminiferal burrow formation increases the oxygen penetration depth in the sediment, leading to a change in the structure of the prokaryotic community.
Masahiko Fujii, Ryuji Hamanoue, Lawrence Patrick Cases Bernardo, Tsuneo Ono, Akihiro Dazai, Shigeyuki Oomoto, Masahide Wakita, and Takehiro Tanaka
Biogeosciences, 20, 4527–4549, https://doi.org/10.5194/bg-20-4527-2023, https://doi.org/10.5194/bg-20-4527-2023, 2023
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This is the first study of the current and future impacts of climate change on Pacific oyster farming in Japan. Future coastal warming and acidification may affect oyster larvae as a result of longer exposure to lower-pH waters. A prolonged spawning period may harm oyster processing by shortening the shipping period and reducing oyster quality. To minimize impacts on Pacific oyster farming, in addition to mitigation measures, local adaptation measures may be required.
Cited articles
Altieri, A. H. and Gedan, K. B.: Climate change and dead zones, Glob. Change
Biol., 21, 1395–1406, https://doi.org/10.1111/gcb.12754, 2015.
Association for the Physical Sciences of the Sea: The international
thermodynamic equation of seawater-2010: Calculation and use of
thermodynamic properties Intergovernmental Oceanographic Commission, Manuals and Guides No.
56, UNESCO, 196 pp., 2010.
Bailey, K., Steinberg, C., Davies, C., Galibert, G., Hidas, M., McManus, M.
A., Murphy, T., Newton, J., Roughan, M., and Schaeffer, A.: Coastal Mooring
Observing Networks and Their Data Products: Recommendations for the Next
Decade, Front. Mar. Sci., 6, 180, https://doi.org/10.3389/fmars.2019.00180, 2019.
Beardsley, R. C., Limeburner, R., Yu, H., and Cannon, G. A.: Discharge of the
Changjiang (Yangtze River) into the East China Sea, Cont. Shelf Res.,
4, 57–76, https://doi.org/10.1016/0278-4343(85)90022-6, 1985.
Chang, D., Zhang, F., and Edwards, C. R.: Real-time guidance of underwater
gliders assisted by predictive ocean models, J. Atmos. Ocean. Tech.,
32, 562–578, https://doi.org/10.1175/JTECH-D-14-00098.1, 2015.
Chen, J., Pan, D., Liu, M., Mao, Z., Zhu, Q., Chen, N., Zhang, X., and Tao,
B.: Relationships Between Long-Term Trend of Satellite-Derived Chlorophyll-a
and Hypoxia Off the Changjiang Estuary, Estuar. Coast., 40,
1055–1065, https://doi.org/10.1007/s12237-016-0203-0, 2017.
Chen, Y.-L. L., Chen, H.-Y., Gong, G.-C., Lin, Y.-H., Jan, S., and Takahashi,
M.: Phytoplankton production during a summer coastal upwelling in the East
China Sea, Cont. Shelf Res., 24, 1321–1338, https://doi.org/10.1016/j.csr.2004.04.002,
2004.
Chu, P., Yuchun, C., and Kuninaka, A.: Seasonal variability of the Yellow
Sea/East China Sea surface fluxes and thermohaline structure, Adv. Atmos.
Sci., 22, 1–20, https://doi.org/10.1007/BF02930865, 2005.
Conley, D. J., Björck, S., Bonsdorff, E., Carstensen, J.,
Destouni, G., Gustafsson, B. G., Hietanen, S., Kortekaas, M., Kuosa, H.,
Markus Meier, H. E., Müller-Karulis, B., Nordberg, K.,
Norkko, A., Nürnberg, G., Pitkänen,
H., Rabalais, N. N., Rosenberg, R., Savchuk, O. P., Slomp, C. P., Voss, M.,
Wulff, F., and Zillén, L.: Hypoxia-Related Processes in the Baltic Sea,
Environ. Sci. Technol., 43, 3412–3420, https://doi.org/10.1021/es802762a, 2009.
Csanady, G. T.: Circulation in the Coastal Ocean, Adv. Geophys., 23,
101–183, https://doi.org/10.1016/S0065-2687(08)60331-3, 1981.
Cui, Y., Wu, J., Ren, J., and Xu, J.: Physical dynamics structures and oxygen
budget of summer hypoxia in the Pearl River Estuary, Limnol. Oceanogr.,
64, 131–148, https://doi.org/10.1002/lno.11025, 2019.
Diaz, R. J. and Rosenberg, R.: Spreading dead zones and consequences for
marine ecosystems, Science, 321, 926–929, https://doi.org/10.1126/science.1156401,
2008.
Fofonoff, N. P. and Millard Jr., R. C.: Algorithms for the computation of
fundamental properties of seawater, UNESCO, available at: https://www.oceanbestpractices.net/handle/11329/109 (last access: 30 August 2019), 1983.
Fong, D. A. and Geyer, W. R.: The Alongshore Transport of Freshwater in a
Surface-Trapped River Plume*, J. Phys. Oceanogr., 32, 957–972,
https://doi.org/10.1175/1520-0485(2002)032<0957:TATOFI>2.0.CO;2,
2002.
Große, F., Fennel, K., Zhang, H., and Laurent, A.: Quantifying the contributions of riverine vs. oceanic nitrogen to hypoxia in the East China Sea, Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-342, in review, 2019.
Guo, Y., Rong, Z., Li, B., Xu, Z., Li, P., and Li, X.: Physical processes
causing the formation of hypoxia off the Changjiang estuary after Typhoon
Chan-hom, 2015, J. Oceanol. Limnol., 37, 1–17,
https://doi.org/10.1007/s00343-019-7336-5, 2019.
Horner-Devine, A. R.: The bulge circulation in the Columbia River plume,
Cont. Shelf Res., 29, 234–251, https://doi.org/10.1016/j.csr.2007.12.012, 2009.
Hu, J. and Wang, X. H.: Progress on upwelling studies in the China seas,
Rev. Geophys., 54, 653–673, https://doi.org/10.1002/2015RG000505, 2016.
Hung, C.-C., Chung, C.-C., Gong, G.-C., Jan, S., Tsai, Y., Chen, K.-S.,
Chou, W. C., Lee, M.-A., Chang, Y., Chen, M.-H., Yang, W.-R., Tseng, C.-J.,
and Gawarkiewicz, G.: Nutrient supply in the Southern East China Sea after
Typhoon Morakot, J. Mar. Res., 71, 133–149,
https://doi.org/10.1357/002224013807343425, 2013.
Kang, Y., Pan, D., Bai, Y., He, X., Chen, X., Chen, C.-T. A., and Wang, D.:
Areas of the global major river plumes, Acta Oceanol. Sin., 32, 79–88,
https://doi.org/10.1007/s13131-013-0269-5, 2013.
Large, W. G. and Pond, S.: Open Ocean Momentum Flux Measurements in Moderate
to Strong Winds, J. Phys. Oceanogr., 11, 324–336,
https://doi.org/10.1175/1520-0485(1981)011<0324:OOMFMI>2.0.CO;2,
1981.
Lentz, S. J. and Helfrich, K. R.: Buoyant gravity currents along a sloping
bottom in a rotating fluid, J. Fluid Mech, 464, 251–278,
https://doi.org/10.1017/S0022112002008868, 2002.
Li, D., Jing, Z., Daji, H., Ying, W., and Jun, L.: Oxygen depletion off the
Changjiang (Yangtze River) Estuary, Sci. China Ser. D, 45, 1137–1146, https://doi.org/10.1360/02yd9110, 2002.
Li, L., He, Z., Xia, Y., and Dou, X.: Dynamics of sediment transport and
stratification in Changjiang River Estuary, China, Estuar. Coast. Shelf
S., 213, 1–17, https://doi.org/10.1016/J.ECSS.2018.08.002, 2018.
Li, M. and Chen, Z.: An Assessment of Saltwater Intrusion in the Changjiang
(Yangtze) River Estuary, China, Coasts and Estuaries, 31–43,
https://doi.org/10.1016/B978-0-12-814003-1.00002-2, 2019.
Li, M. and Rong, Z.: Effects of tides on freshwater and volume transports in
the Changjiang River plume, J. Geophys. Res., 117, 6027,
https://doi.org/10.1029/2011JC007716, 2012.
Li, Y. L.: Seasonal Hypoxia and its Affecting Factors in the Yangtze River
Estuary, Ocean University of China, Qingdao, 2015 (in Chinese).
Li, Z., Song, S., Li, C., and Yu, Z.: The sinking of the phytoplankton
community and its contribution to seasonal hypoxia in the Changjiang
(Yangtze River) estuary and its adjacent waters, Estuar. Coast. Shelf S.,
208, 170–179, https://doi.org/10.1016/J.ECSS.2018.05.007, 2018.
Liblik, T., Karstensen, J., Testor, P., Alenius, P., Hayes, D., Ruiz, S.,
Heywood, K. J., Pouliquen, S., Mortier, L., and Mauri, E.: Potential for an
underwater glider component as part of the Global Ocean Observing System,
Methods Oceanogr., 17, 50–82, https://doi.org/10.1016/j.mio.2016.05.001, 2016.
Lie, H.-J. and Cho, C.-H.: Recent advances in understanding the circulation
and hydrography of the East China Sea, Fish. Oceanogr., 11, 318–328,
https://doi.org/10.1046/j.1365-2419.2002.00215.x, 2002.
Lie, H.-J. and Cho, C.-H.: Seasonal circulation patterns of the Yellow and
East China Seas derived from satellite-tracked drifter trajectories and
hydrographic observations, Prog. Oceanogr., 146, 121–141,
https://doi.org/10.1016/J.POCEAN.2016.06.004, 2016.
Lips, U., Kikas, V., Liblik, T., and Lips, I.: Multi-sensor in situ observations to resolve the sub-mesoscale features in the stratified Gulf of Finland, Baltic Sea, Ocean Sci., 12, 715–732, https://doi.org/10.5194/os-12-715-2016, 2016.
Liu, W., Song, J., Huamao, Y., Li, N., Xuegang, L. I., and Liqin, D.:
Dissolved barium as a tracer of Kuroshio incursion in the Kuroshio region
east of Taiwan Island and the adjacent East China Sea, Sci. China Earth
Sci., 60, 1356–1367, https://doi.org/10.1007/s11430-016-9039-7, 2017.
Meissner, T., Wentz, F. J., and Manaster, A.: Remote Sensing Systems SMAP
Ocean Surface Salinities [Level 2C, Level 3 Running 8-day, Level 3 Monthly],
Version 3.0 validated release, Remote Sensing Systems, Santa Rosa, CA, USA, https://doi.org/10.5067/SMP3A-3SPCS, 2018.
Moon, J.-H., Kim, T., Son, Y. B., Hong, J.-S., Lee, J.-H., Chang, P.-H., and
Kim, S.-K.: Contribution of low-salinity water to sea surface warming of the
East China Sea in the summer of 2016, Prog. Oceanogr., 175, 68–80,
https://doi.org/10.1016/j.pocean.2019.03.012, 2019.
Ni, X., Huang, D., Zeng, D., Zhang, T., Li, H., and Chen, J.: The impact of
wind mixing on the variation of bottom dissolved oxygen off the Changjiang
Estuary during summer, J. Marine Syst., 154, 122–130,
https://doi.org/10.1016/j.jmarsys.2014.11.010, 2016.
Ning, X., Lin, C., Su, J., Liu, C., Hao, Q., and Le, F.: Long-term changes of
dissolved oxygen, hypoxia, and the responses of the ecosystems in the East
China Sea from 1975 to 1995, J. Oceanogr., 67, 59–75,
https://doi.org/10.1007/s10872-011-0006-7, 2011.
Obenour, D. R., Scavia, D., Rabalais, N. N., Turner, R. E., and Michalak, A.
M.: Retrospective Analysis of Midsummer Hypoxic Area and Volume in the
Northern Gulf of Mexico, 1985–2011, Environ. Sci. Technol., 47,
9808–9815, https://doi.org/10.1021/es400983g, 2013.
Peng, L., Benwei, S., Yaping, W., Weihua, Q., Yangang, L., and Jian, C.:
Analysis of the characteristics of offshore currents in the Changjiang
(Yangtze River) estuarine waters based on buoy observations, Acta Oceanol.
Sin., 36, 13–20, https://doi.org/10.1007/s13131-017-0973-7, 2017.
Qian, W., Dai, M., Xu, M., Kao, S. ji, Du, C., Liu, J., Wang, H., Guo, L.,
and Wang, L.: Non-local drivers of the summer hypoxia in the East China Sea
off the Changjiang Estuary, Estuar. Coast. Shelf S., 198, 393–399,
https://doi.org/10.1016/j.ecss.2016.08.032, 2017.
Ren, F., Fan, D., Wu, Y., and Zhao, Q.: The evolution of hypoxia off the
Changjiang Estuary in the last 3000 years: Evidence from benthic
foraminifera and elemental geochemistry, Mar. Geol., 417, 106039,
https://doi.org/10.1016/J.MARGEO.2019.106039, 2019.
Rudnick, D. L.: Ocean Research Enabled by Underwater Gliders, Annu. Rev. Mar.
Sci., 8, 519–541, https://doi.org/10.1146/annurev-marine-122414-033913, 2016.
Sun, H., Yang, Q., Zhao, W., Liang, X., and Tian, J.: Temporal variability of
diapycnal mixing in the northern South China Sea, J. Geophys. Res.-Ocean.,
121, 8840–8848, https://doi.org/10.1002/2016JC012044, 2016.
Testa, J. M. and Kemp, W. M.: Spatial and Temporal Patterns of
Winter–Spring Oxygen Depletion in Chesapeake Bay Bottom Water, Estuaries
and Coasts, 37, 1432–1448, https://doi.org/10.1007/s12237-014-9775-8, 2014.
Tseng, Y.-F., Lin, J., Dai, M., and Kao, S.-J.: Joint effect of freshwater plume and coastal upwelling on phytoplankton growth off the Changjiang River, Biogeosciences, 11, 409–423, https://doi.org/10.5194/bg-11-409-2014, 2014.
Vaquer-Sunyer, R. and Duarte, C. M.: Thresholds of hypoxia for marine
biodiversity, P. Natl. Acad. Sci. USA, 105, 15452–15457,
https://doi.org/10.1073/pnas.0803833105, 2008.
Venkatesan, R., Lix, J. K., Phanindra Reddy, A., Arul Muthiah, M., and
Atmanand, M. A.: Two decades of operating the Indian moored buoy network:
significance and impact, J. Oper. Oceanogr., 9, 45–54,
https://doi.org/10.1080/1755876X.2016.1182792, 2016.
Wang, B. and Wang, X.: Chemical hydrography of coastal upwelling in the East
China Sea, Chin. J. Oceanol. Limn., 25, 16–26,
https://doi.org/10.1007/s00343-007-0016-x, 2007.
Wang, B., Wei, Q., Chen, J., and Xie, L.: Annual cycle of hypoxia off the
Changjiang (Yangtze River) Estuary, Mar. Environ. Res., 77, 1–5,
https://doi.org/10.1016/j.marenvres.2011.12.007, 2012.
Wang, B., Chen, J., Jin, H., Li, H., Huang, D., and Cai, W.-J.: Diatom
bloom-derived bottom water hypoxia off the Changjiang estuary, with and
without typhoon influence, Limnol. Oceanogr., 62, 1552–1569,
https://doi.org/10.1002/lno.10517, 2017.
Wang, H., Dai, M., Liu, J., Kao, S.-J., Zhang, C., Cai, W.-J., Wang, G.,
Qian, W., Zhao, M., and Sun, Z.: Eutrophication-Driven Hypoxia in the East
China Sea off the Changjiang Estuary, Environ. Sci. Technol., 50,
2255–2263, https://doi.org/10.1021/acs.est.5b06211, 2016.
Wei, Q., Wang, B., Yu, Z., Chen, J., and Xue, L.: Mechanisms leading to the
frequent occurrences of hypoxia and a preliminary analysis of the associated
acidification off the Changjiang estuary in summer, Sci. China Earth Sci.,
60, 360–381, https://doi.org/10.1007/s11430-015-5542-8, 2017a.
Wei, Q., Yu, Z., Wang, B., Wu, H., Sun, J., Zhang, X., Fu, M., Xia, C., and
Wang, H.: Offshore detachment of the Changjiang River plume and its
ecological impacts in summer, J. Oceanogr., 73, 277–294,
https://doi.org/10.1007/s10872-016-0402-0, 2017b.
Weiss, R. F.: The solubility of nitrogen, oxygen and argon in water and
seawater, Deep-Sea Res. Oceanogr. Abstr., 17, 721–735,
https://doi.org/10.1016/0011-7471(70)90037-9, 1970.
Wu, H., Deng, B., Yuan, R., Hu, J., Gu, J., Shen, F., Zhu, J., and Zhang, J.:
Detiding Measurement on Transport of the Changjiang-Derived Buoyant Coastal
Current, J. Phys. Oceanogr., 43, 2388–2399,
https://doi.org/10.1175/JPO-D-12-0158.1, 2013.
Wu, Y., Fan, D., Wang, D., and Yin, P.: Increasing hypoxia in the Changjiang
Estuary during the last three decades deciphered from sedimentary
redox-sensitive elements, Mar. Geol., 419, 106044,
https://doi.org/10.1016/J.MARGEO.2019.106044, 2019.
Xu, Q., Zhang, S., Cheng, Y., and Zuo, J.: Interannual Feature of Summer
Upwelling around the Zhoushan Islands in the East China Sea, J. Coastal Res.,
331, 125–134, https://doi.org/10.2112/JCOASTRES-D-15-00197.1, 2017.
Xu, Z., Ma, J., Wang, H., Hu, Y., Yang, G., Deng, W., Xu, Z., Ma, J., Wang,
H., Hu, Y., Yang, G., and Deng, W.: River Discharge and Saltwater Intrusion
Level Study of Yangtze River Estuary, China, Water, 10, 683,
https://doi.org/10.3390/w10060683, 2018.
Xuan, J.-L., Huang, D., Zhou, F., Zhu, X.-H., and Fan, X.: The role of wind
on the detachment of low salinity water in the Changjiang Estuary in summer,
J. Geophys. Res.-Oceans, 117, C10004, https://doi.org/10.1029/2012JC008121, 2012.
Yang, L., Chen, Z., Sun, Z., and Hu, J.: Sectional characteristics of
temperature, salinity and density off the central Zhejiang coast in the
spring of 2016, Acta Oceanol. Sin., 38, 175–182,
https://doi.org/10.1007/s13131-019-1421-7, 2019.
Ye, W., Zhang, G., Zhu, Z., Han, Y., Wang, L., and Sun, M.: Methane
distribution and sea-to-air flux in the East China Sea during the summer of
2013: Impact of hypoxia, Deep-Sea Res. Pt. II, 124,
74–83, https://doi.org/10.1016/J.DSR2.2015.01.008, 2016.
Zhang, J., Liu, S. M., Ren, J. L., Wu, Y., and Zhang, G. L.: Nutrient
gradients from the eutrophic Changjiang (Yangtze River) Estuary to the
oligotrophic Kuroshio waters and re-evaluation of budgets for the East China
Sea Shelf, Prog. Oceanogr., 74, 449–478,
https://doi.org/10.1016/j.pocean.2007.04.019, 2007.
Zhang, L., Liu, Z., Zhang, J., Hong, G. H., Park, Y., and Zhang, H. F.:
Reevaluation of mixing among multiple water masses in the shelf: An example
from the East China Sea, Cont. Shelf Res., 27, 1969–1979,
https://doi.org/10.1016/J.CSR.2007.04.002, 2007.
Zhang, W., Wu, H., and Zhu, Z.: Transient Hypoxia Extent Off Changjiang River
Estuary due to Mobile Changjiang River Plume, J. Geophys. Res.-Oceans,
123, 9196–9211, https://doi.org/10.1029/2018JC014596, 2018.
Zhang, W., Wu, H., Hetland, R. D., and Zhu, Z.: On Mechanisms Controlling the
Seasonal Hypoxia Hot Spots off the Changjiang River Estuary, J. Geophys.
Res.-Oceans, 124, 8683–8700, https://doi.org/10.1029/2019JC015322, 2019.
Zheng, J., Gao, S., Liu, G., Wang, H., and Zhu, X.: Modeling the impact of river discharge and wind on the hypoxia off Yangtze Estuary, Nat. Hazards Earth Syst. Sci., 16, 2559–2576, https://doi.org/10.5194/nhess-16-2559-2016, 2016.
Zhou, Z., Yu, R., Sun, C., Feng, M., and Zhou, M.: Impacts of Changjiang
River Discharge and Kuroshio Intrusion on the Diatom and Dinoflagellate
Blooms in the East China Sea, J. Geophys. Res.-Oceans, 124, 5244–5257,
https://doi.org/10.1029/2019JC015158, 2019.
Zhu, J., Zhu, Z., Lin, J., Wu, H., and Zhang, J.: Distribution of hypoxia and
pycnocline off the Changjiang Estuary, China, J. Marine Syst., 154, 28–40,
https://doi.org/10.1016/j.jmarsys.2015.05.002, 2016.
Zhu, Z.-Y., Zhang, J., Wu, Y., Zhang, Y.-Y., Lin, J., and Liu, S.-M.: Hypoxia
off the Changjiang (Yangtze River) Estuary: Oxygen depletion and organic
matter decomposition, Mar. Chem., 125, 108–116,
https://doi.org/10.1016/J.MARCHEM.2011.03.005, 2011.
Zhu, Z. Y., Wu, H., Liu, S. M., Wu, Y., Huang, D. J., Zhang, J., and Zhang,
G. Sen: Hypoxia off the Changjiang (Yangtze River) estuary and in the
adjacent East China Sea: Quantitative approaches to estimating the tidal
impact and nutrient regeneration, Mar. Pollut. Bull., 125, 103–114,
https://doi.org/10.1016/j.marpolbul.2017.07.029, 2017.
Zuo, J., Song, J., Yuan, H., Li, X., Li, N., and Duan, L.: Impact of Kuroshio
on the dissolved oxygen in the East China Sea region, J. Oceanol. Limnol.,
37, 513–524, https://doi.org/10.1007/s00343-019-7389-5, 2019.
Short summary
Multiple factors have been accused of triggering coastal hypoxia off the Changjiang Estuary. In situ observations, remote sensing and numerical simulation data were used to study dissolved oxygen depletion in the area. Oxygen distributions can be explained by wind forcing and river discharge, as well as concurrent features in surface and deep layer circulation. If summer monsoon prevails, hypoxia more likely occurs in the north while hypoxia in the south appears if the summer monsoon is weaker.
Multiple factors have been accused of triggering coastal hypoxia off the Changjiang Estuary. In...
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