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.
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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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.
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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.
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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.
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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
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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The additionality problem of ocean alkalinity enhancement
Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings
Revisiting the applicability and constraints of molybdenum- and uranium-based paleo redox proxies: comparing two contrasting sill fjords
Influence of a small submarine canyon on biogenic matter export flux in the lower St. Lawrence Estuary, eastern Canada
Single-celled bioturbators: benthic foraminifera mediate oxygen penetration and prokaryotic diversity in intertidal sediment
Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan
Unusual Hemiaulus Bloom Influences Ocean Productivity in Northeast U.S. Shelf Waters
Multiple nitrogen sources for primary production inferred from δ13C and δ15N in the southern Sea of Japan
Influence of manganese cycling on alkalinity in the redox stratified water column of Chesapeake Bay
UAV approaches for improved mapping of vegetation cover and estimation of carbon storage of small saltmarshes: examples from Loch Fleet, northeast Scotland
Estuarine flocculation dynamics of organic carbon and metals from boreal acid sulfate soils
Drivers of particle sinking velocities in the Peruvian upwelling system
Marine anoxia initiates giant sulfur-bacteria mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland
Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia
Considerations for hypothetical carbon dioxide removal via alkalinity addition in the Amazon River watershed
Above- and Belowground Plant Mercury Dynamics in a Salt Marsh Estuary in Massachusetts, USA
High metabolism and periodic hypoxia associated with drifting macrophyte detritus in the shallow subtidal Baltic Sea
Oceanographic Processes Favoring Deoxygenation Inside Patagonian Fjords
Production and accumulation of reef framework by calcifying corals and macroalgae on a remote Indian Ocean cay
Zooplankton community succession and trophic links during a mesocosm experiment in the coastal upwelling off Callao Bay (Peru)
Temporal and spatial evolution of bottom-water hypoxia in the St Lawrence estuarine system
Significant nutrient consumption in the dark subsurface layer during a diatom bloom: a case study on Funka Bay, Hokkaido, Japan
Contrasts in dissolved, particulate, and sedimentary organic carbon from the Kolyma River to the East Siberian Shelf
Sediment quality assessment in an industrialized Greek coastal marine area (western Saronikos Gulf)
Limits and CO2 equilibration of near-coast alkalinity enhancement
Role of phosphorus in the seasonal deoxygenation of the East China Sea shelf
Interannual variability of the initiation of the phytoplankton growing period in two French coastal ecosystems
Iron “Ore” Nothing: Benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
Spatio-temporal distribution, photoreactivity and environmental control of dissolved organic matter in the sea-surface microlayer of the eastern marginal seas of China
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Dewi Langlet, Florian Mermillod-Blondin, Noémie Deldicq, Arthur Bauville, Gwendoline Duong, Lara Konecny, Mylène Hugoni, Lionel Denis, and Vincent M. P. Bouchet
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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.
S. Alejandra Castillo Cieza, Rachel H. R. Stanley, Pierre Marrec, Diana N. Fontaine, E. Taylor Crockford, Dennis J. McGillicuddy, Arshia Mehta, Susanne Menden-Deuer, Emily E. Peacock, Tatiana A. Rynearson, Zoe O. Sandwith, Weifeng Zhang, and Heidi M. Sosik
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-153, https://doi.org/10.5194/bg-2023-153, 2023
Revised manuscript accepted for BG
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The coastal ocean in northeastern USA provides many services, including fisheries and habitat for threatened species. In summer 2019, a bloom occurred of an unusual large 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 maybe become more prevalent as the ocean warms due to climate change.
Taketoshi Kodama, Atsushi Nishimoto, Ken-ichi Nakamura, Misato Nakae, Naoki Iguchi, Yosuke Igeta, and Yoichi Kogure
Biogeosciences, 20, 3667–3682, https://doi.org/10.5194/bg-20-3667-2023, https://doi.org/10.5194/bg-20-3667-2023, 2023
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Carbon and nitrogen are essential elements for organisms; their stable isotope ratios (13C : 12C, 15N : 14N) are useful tools for understanding turnover and movement in the ocean. In the Sea of Japan, the environment is rapidly being altered by human activities. The 13C : 12C of small organic particles is increased by active carbon fixation, and phytoplankton growth increases the values. The 15N : 14N variations suggest that nitrates from many sources contribute to organic production.
Aubin Thibault de Chanvalon, George W. Luther, Emily R. Estes, Jennifer Necker, Bradley M. Tebo, Jianzhong Su, and Wei-Jun Cai
Biogeosciences, 20, 3053–3071, https://doi.org/10.5194/bg-20-3053-2023, https://doi.org/10.5194/bg-20-3053-2023, 2023
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The intensity of the oceanic trap of CO2 released by anthropogenic activities depends on the alkalinity brought by continental weathering. Between ocean and continent, coastal water and estuaries can limit or favour the alkalinity transfer. This study investigate new interactions between dissolved metals and alkalinity in the oxygen-depleted zone of estuaries.
William Hiles, Lucy Catherine Miller, Craig Smeaton, and William Edward Newns Austin
EGUsphere, https://doi.org/10.5194/egusphere-2023-1185, https://doi.org/10.5194/egusphere-2023-1185, 2023
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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.
Joonas J. Virtasalo, Peter Österholm, and Eero Asmala
Biogeosciences, 20, 2883–2901, https://doi.org/10.5194/bg-20-2883-2023, https://doi.org/10.5194/bg-20-2883-2023, 2023
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We mixed acidic metal-rich river water from acid sulfate soils and seawater in the laboratory to study the flocculation of dissolved metals and organic matter in estuaries. Al and Fe flocculated already at a salinity of 0–2 to large organic flocs (>80 µm size). Precipitation of Al and Fe hydroxide flocculi (median size 11 µm) began when pH exceeded ca. 5.5. Mn transferred weakly to Mn hydroxides and Co to the flocs. Up to 50 % of Cu was associated with the flocs, irrespective of seawater mixing.
Moritz Baumann, Allanah Joy Paul, Jan Taucher, Lennart Thomas Bach, Silvan Goldenberg, Paul Stange, Fabrizio Minutolo, and Ulf Riebesell
Biogeosciences, 20, 2595–2612, https://doi.org/10.5194/bg-20-2595-2023, https://doi.org/10.5194/bg-20-2595-2023, 2023
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The sinking velocity of marine particles affects how much atmospheric CO2 is stored inside our oceans. We measured particle sinking velocities in the Peruvian upwelling system and assessed their physical and biochemical drivers. We found that sinking velocity was mainly influenced by particle size and porosity, while ballasting minerals played only a minor role. Our findings help us to better understand the particle sinking dynamics in this highly productive marine system.
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhoefer, Felix Janßen, Na Liu, Jonathan Tarn, Frank Kinnaman, David L. Valentine, and Tina Treude
EGUsphere, https://doi.org/10.5194/egusphere-2023-1198, https://doi.org/10.5194/egusphere-2023-1198, 2023
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Declining oxygen 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 oxygen depletion events through their unique chemoautotrophic metabolism. Our study shows how changes in seafloor microbiology and geochemistry brought on by declining oxygen concentrations can help these mats grow, and how that growth affects the basin.
Kyle E. Hinson, Marjorie A. M. Friedrichs, Raymond G. Najjar, Maria Herrmann, Zihao Bian, Gopal Bhatt, Pierre St-Laurent, Hanqin Tian, and Gary Shenk
Biogeosciences, 20, 1937–1961, https://doi.org/10.5194/bg-20-1937-2023, https://doi.org/10.5194/bg-20-1937-2023, 2023
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Climate impacts are essential for environmental managers to consider when implementing nutrient reduction plans designed to reduce hypoxia. This work highlights relative sources of uncertainty in modeling regional climate impacts on the Chesapeake Bay watershed and consequent declines in bay oxygen levels. The results demonstrate that planned water quality improvement goals are capable of reducing hypoxia levels by half, offsetting climate-driven impacts on terrestrial runoff.
Linquan Mu, Jaime B. Palter, and Hongjie Wang
Biogeosciences, 20, 1963–1977, https://doi.org/10.5194/bg-20-1963-2023, https://doi.org/10.5194/bg-20-1963-2023, 2023
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Enhancing ocean alkalinity accelerates carbon dioxide removal from the atmosphere. We hypothetically added alkalinity to the Amazon River and examined the increment of the carbon uptake by the Amazon plume. We also investigated the minimum alkalinity addition in which this perturbation at the river mouth could be detected above the natural variability.
Ting Wang, Buyun Du, Inke Forbrich, Jun Zhou, Joshua Polen, Elsie M. Sunderland, Prentiss H. Balcom, Celia Y. Chen, and Daniel Obrist
EGUsphere, https://doi.org/10.5194/egusphere-2023-720, https://doi.org/10.5194/egusphere-2023-720, 2023
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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. While belowground plant tissues mostly take up Hg from soils. Overall, the salt marsh currently serves as a small net Hg sink.
Karl M. Attard, Anna Lyssenko, and Iván F. Rodil
Biogeosciences, 20, 1713–1724, https://doi.org/10.5194/bg-20-1713-2023, https://doi.org/10.5194/bg-20-1713-2023, 2023
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Aquatic plants produce a large amount of organic matter through photosynthesis that, following erosion, is deposited on the seafloor. In this study, we show that plant detritus can trigger low-oxygen conditions (hypoxia) in shallow coastal waters, making conditions challenging for most marine animals. We propose that the occurrence of hypoxia may be underestimated because measurements typically do not consider the region closest to the seafloor, where detritus accumulates.
Pamela Linford, Iván Pérez-Santos, Paulina Montero, Patricio 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
EGUsphere, https://doi.org/10.5194/egusphere-2023-706, https://doi.org/10.5194/egusphere-2023-706, 2023
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The Patagonian fjord is one world region where low-oxygen water and hypoxia conditions is observed. An in-situ data set was used to quantify the mechanism involved in the presence of low-oxygen water and hypoxic 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.
M. James McLaughlin, Cindy Bessey, Gary A. Kendrick, John Keesing, and Ylva S. Olsen
Biogeosciences, 20, 1011–1026, https://doi.org/10.5194/bg-20-1011-2023, https://doi.org/10.5194/bg-20-1011-2023, 2023
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Coral reefs face increasing pressures from environmental change at present. The coral reef framework is produced by corals and calcifying algae. The Kimberley region of Western Australia has escaped land-based anthropogenic impacts. Specimens of the dominant coral and algae were collected from Browse Island's reef platform and incubated in mesocosms to measure calcification and production patterns of oxygen. This study provides important data on reef building and climate-driven effects.
Patricia Ayón Dejo, Elda Luz Pinedo Arteaga, Anna Schukat, Jan Taucher, Rainer Kiko, Helena Hauss, Sabrina Dorschner, Wilhelm Hagen, Mariona Segura-Noguera, and Silke Lischka
Biogeosciences, 20, 945–969, https://doi.org/10.5194/bg-20-945-2023, https://doi.org/10.5194/bg-20-945-2023, 2023
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Ocean upwelling regions are highly productive. With ocean warming, severe changes in upwelling frequency and/or intensity and expansion of accompanying oxygen minimum zones are projected. In a field experiment off Peru, we investigated how different upwelling intensities affect the pelagic food web and found failed reproduction of dominant zooplankton. The changes projected could severely impact the reproductive success of zooplankton communities and the pelagic food web in upwelling regions.
Mathilde Jutras, Alfonso Mucci, Gwenaëlle Chaillou, William A. Nesbitt, and Douglas W. R. Wallace
Biogeosciences, 20, 839–849, https://doi.org/10.5194/bg-20-839-2023, https://doi.org/10.5194/bg-20-839-2023, 2023
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The deep waters of the lower St Lawrence Estuary and gulf have, in the last decades, experienced a strong decline in their oxygen concentration. Below 65 µmol L-1, the waters are said to be hypoxic, with dire consequences for marine life. We show that the extent of the hypoxic zone shows a seven-fold increase in the last 20 years, reaching 9400 km2 in 2021. After a stable period at ~ 65 µmol L⁻¹ from 1984 to 2019, the oxygen level also suddenly decreased to ~ 35 µmol L-1 in 2020.
Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, and Atsushi Ooki
Biogeosciences, 20, 421–438, https://doi.org/10.5194/bg-20-421-2023, https://doi.org/10.5194/bg-20-421-2023, 2023
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We conducted repetitive observations in Funka Bay, Japan, during the spring bloom 2019. We found nutrient concentration decreases in the dark subsurface layer during the bloom. Incubation experiments confirmed that diatoms could consume nutrients at a substantial rate, even in darkness. We concluded that the nutrient reduction was mainly caused by nutrient consumption by diatoms in the dark.
Dirk Jong, Lisa Bröder, Tommaso Tesi, Kirsi H. Keskitalo, Nikita Zimov, Anna Davydova, Philip Pika, Negar Haghipour, Timothy I. Eglinton, and Jorien E. Vonk
Biogeosciences, 20, 271–294, https://doi.org/10.5194/bg-20-271-2023, https://doi.org/10.5194/bg-20-271-2023, 2023
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With this study, we want to highlight the importance of studying both land and ocean together, and water and sediment together, as these systems function as a continuum, and determine how organic carbon derived from permafrost is broken down and its effect on global warming. Although on the one hand it appears that organic carbon is removed from sediments along the pathway of transport from river to ocean, it also appears to remain relatively ‘fresh’, despite this removal and its very old age.
Georgia Filippi, Manos Dassenakis, Vasiliki Paraskevopoulou, and Konstantinos Lazogiannis
Biogeosciences, 20, 163–189, https://doi.org/10.5194/bg-20-163-2023, https://doi.org/10.5194/bg-20-163-2023, 2023
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The pollution of the western Saronikos Gulf from heavy metals has been examined through the study of marine sediment cores. It is a deep gulf (maximum depth 440 m) near Athens affected by industrial and volcanic activity. Eight cores were received from various stations and depths and analysed for their heavy metal content and geochemical characteristics. The results were evaluated by using statistical methods, environmental indicators and comparisons with old data.
Jing He and Michael D. Tyka
Biogeosciences, 20, 27–43, https://doi.org/10.5194/bg-20-27-2023, https://doi.org/10.5194/bg-20-27-2023, 2023
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Recently, ocean alkalinity enhancement (OAE) has gained interest as a scalable way to address the urgent need for negative CO2 emissions. In this paper we examine the capacity of different coastlines to tolerate alkalinity enhancement and the time scale of CO2 uptake following the addition of a given quantity of alkalinity. The results suggest that OAE has significant potential and identify specific favorable and unfavorable coastlines for its deployment.
Arnaud Laurent, Haiyan Zhang, and Katja Fennel
Biogeosciences, 19, 5893–5910, https://doi.org/10.5194/bg-19-5893-2022, https://doi.org/10.5194/bg-19-5893-2022, 2022
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The Changjiang is the main terrestrial source of nutrients to the East China Sea (ECS). Nutrient delivery to the ECS has been increasing since the 1960s, resulting in low oxygen (hypoxia) during phytoplankton decomposition in summer. River phosphorus (P) has increased less than nitrogen, and therefore, despite the large nutrient delivery, phytoplankton growth can be limited by the lack of P. Here, we investigate this link between P limitation, phytoplankton production/decomposition, and hypoxia.
Coline Poppeschi, Guillaume Charria, Anne Daniel, Romaric Verney, Peggy Rimmelin-Maury, Michaël Retho, Eric Goberville, Emilie Grossteffan, and Martin Plus
Biogeosciences, 19, 5667–5687, https://doi.org/10.5194/bg-19-5667-2022, https://doi.org/10.5194/bg-19-5667-2022, 2022
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This paper aims to understand interannual changes in the initiation of the phytoplankton growing period (IPGP) in the current context of global climate changes over the last 20 years. An important variability in the timing of the IPGP is observed with a trend towards a later IPGP during this last decade. The role and the impact of extreme events (cold spells, floods, and wind burst) on the IPGP is also detailed.
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 Discuss., https://doi.org/10.5194/bg-2022-237, https://doi.org/10.5194/bg-2022-237, 2022
Revised manuscript accepted for BG
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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.
Lin Yang, Jing Zhang, Anja Engel, and Gui-Peng Yang
Biogeosciences, 19, 5251–5268, https://doi.org/10.5194/bg-19-5251-2022, https://doi.org/10.5194/bg-19-5251-2022, 2022
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Enrichment factors of dissolved organic matter (DOM) in the eastern marginal seas of China exhibited a significant spatio-temporal variation. Photochemical and enrichment processes co-regulated DOM enrichment in the sea-surface microlayer (SML). Autochthonous DOM was more frequently enriched in the SML than terrestrial DOM. DOM in the sub-surface water exhibited higher aromaticity than that in the SML.
Mona Norbisrath, Johannes Pätsch, Kirstin Dähnke, Tina Sanders, Gesa Schulz, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 19, 5151–5165, https://doi.org/10.5194/bg-19-5151-2022, https://doi.org/10.5194/bg-19-5151-2022, 2022
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Total alkalinity (TA) regulates the oceanic storage capacity of atmospheric CO2. TA is also metabolically generated in estuaries and influences coastal carbon storage through its inflows. We used water samples and identified the Hamburg port area as the one with highest TA generation. Of the overall riverine TA load, 14 % is generated within the estuary. Using a biogeochemical model, we estimated potential effects on the coastal carbon storage under possible anthropogenic and climate changes.
Le Zhang and Z. George Xue
Biogeosciences, 19, 4589–4618, https://doi.org/10.5194/bg-19-4589-2022, https://doi.org/10.5194/bg-19-4589-2022, 2022
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We adopt a high-resolution carbon model for the Gulf of Mexico (GoM) and calculate the decadal trends of important carbon system variables in the GoM from 2001 to 2019. The GoM surface CO2 values experienced a steady increase over the past 2 decades, and the ocean surface pH is declining. Although carbonate saturation rates remain supersaturated with aragonite, they show a slightly decreasing trend. The northern GoM is a stronger carbon sink than we thought.
Michael M. Whitney
Biogeosciences, 19, 4479–4497, https://doi.org/10.5194/bg-19-4479-2022, https://doi.org/10.5194/bg-19-4479-2022, 2022
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Coastal hypoxia is a major environmental problem of increasing severity. The 21st-century projections analyzed indicate global coastal waters will warm and experience rapid declines in oxygen. The forecasted median coastal trends for increasing sea surface temperature and decreasing oxygen capacity are 48 % and 18 % faster than the rates observed over the last 4 decades. Existing hypoxic areas are expected to worsen, and new hypoxic areas likely will emerge under these warming-related pressures.
Bryce Van Dam, Nele Lehmann, Mary A. Zeller, Andreas Neumann, Daniel Pröfrock, Marko Lipka, Helmuth Thomas, and Michael Ernst Böttcher
Biogeosciences, 19, 3775–3789, https://doi.org/10.5194/bg-19-3775-2022, https://doi.org/10.5194/bg-19-3775-2022, 2022
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We quantified sediment–water exchange at shallow sites in the North and Baltic seas. We found that porewater irrigation rates in the former were approximately twice as high as previously estimated, likely driven by relatively high bioirrigative activity. In contrast, we found small net fluxes of alkalinity, ranging from −35 µmol m−2 h−1 (uptake) to 53 µmol m−2 h−1 (release). We attribute this to low net denitrification, carbonate mineral (re-)precipitation, and sulfide (re-)oxidation.
Jiaying Abby Guo, Robert Strzepek, Anusuya Willis, Aaron Ferderer, and Lennart Thomas Bach
Biogeosciences, 19, 3683–3697, https://doi.org/10.5194/bg-19-3683-2022, https://doi.org/10.5194/bg-19-3683-2022, 2022
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Ocean alkalinity enhancement is a CO2 removal method with significant potential, but it can lead to a perturbation of the ocean with trace metals such as nickel. This study tested the effect of increasing nickel concentrations on phytoplankton growth and photosynthesis. We found that the response to nickel varied across the 11 phytoplankton species tested here, but the majority were rather insensitive. We note, however, that responses may be different under other experimental conditions.
Malcolm E. Scully, W. Rockwell Geyer, David Borkman, Tracy L. Pugh, Amy Costa, and Owen C. Nichols
Biogeosciences, 19, 3523–3536, https://doi.org/10.5194/bg-19-3523-2022, https://doi.org/10.5194/bg-19-3523-2022, 2022
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For two consecutive summers, the bottom waters in southern Cape Cod Bay became severely depleted of dissolved oxygen. Low oxygen levels in bottom waters have never been reported in this area before, and this unprecedented occurrence is likely the result of a new algae species that recently began blooming during the late-summer months. We present data suggesting that blooms of this new species are the result of regional climate change including warmer waters and changes in summer winds.
Zheng Chen, Bin Wang, Chuang Xu, Zhongren Zhang, Shiyu Li, and Jiatang Hu
Biogeosciences, 19, 3469–3490, https://doi.org/10.5194/bg-19-3469-2022, https://doi.org/10.5194/bg-19-3469-2022, 2022
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Deterioration of low-oxygen conditions in the coastal waters off Hong Kong was revealed by monitoring data over two decades. The declining wind forcing and the increasing nutrient input contributed significantly to the areal expansion and intense deterioration of low-oxygen conditions. Also, the exacerbated eutrophication drove a shift in the dominant source of organic matter from terrestrial inputs to in situ primary production, which has probably led to an earlier onset of hypoxia in summer.
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.
Justin C. Tiano, Jochen Depestele, Gert Van Hoey, João Fernandes, Pieter van Rijswijk, and Karline Soetaert
Biogeosciences, 19, 2583–2598, https://doi.org/10.5194/bg-19-2583-2022, https://doi.org/10.5194/bg-19-2583-2022, 2022
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This study gives an assessment of bottom trawling on physical, chemical, and biological characteristics in a location known for its strong currents and variable habitats. Although trawl gears only removed the top 1 cm of the seabed surface, impacts on reef-building tubeworms significantly decreased carbon and nutrient cycling. Lighter trawls slightly reduced the impact on fauna and nutrients. Tubeworms were strongly linked to biogeochemical and faunal aspects before but not after trawling.
Inda Brinkmann, Christine Barras, Tom Jilbert, Tomas Næraa, K. Mareike Paul, Magali Schweizer, and Helena L. Filipsson
Biogeosciences, 19, 2523–2535, https://doi.org/10.5194/bg-19-2523-2022, https://doi.org/10.5194/bg-19-2523-2022, 2022
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The concentration of the trace metal barium (Ba) in coastal seawater is a function of continental input, such as riverine discharge. Our geochemical records of the severely hot and dry year 2018, and following wet year 2019, reveal that prolonged drought imprints with exceptionally low Ba concentrations in benthic foraminiferal calcium carbonates of coastal sediments. This highlights the potential of benthic Ba / Ca to trace past climate extremes and variability in coastal marine records.
Shichao Tian, Birgit Gaye, Jianhui Tang, Yongming Luo, Wenguo Li, Niko Lahajnar, Kirstin Dähnke, Tina Sanders, Tianqi Xiong, Weidong Zhai, and Kay-Christian Emeis
Biogeosciences, 19, 2397–2415, https://doi.org/10.5194/bg-19-2397-2022, https://doi.org/10.5194/bg-19-2397-2022, 2022
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We constrain the nitrogen budget and in particular the internal sources and sinks of nitrate in the Bohai Sea by using a mass-based and dual stable isotope approach based on δ15N and δ18O of nitrate. Based on available mass fluxes and isotope data an updated nitrogen budget is proposed. Compared to previous estimates, it is more complete and includes the impact of the interior cycle (nitrification) on the nitrate pool. The main external nitrogen sources are rivers contributing 19.2 %–25.6 %.
Gesa Schulz, Tina Sanders, Justus E. E. van Beusekom, Yoana G. Voynova, Andreas Schöl, and Kirstin Dähnke
Biogeosciences, 19, 2007–2024, https://doi.org/10.5194/bg-19-2007-2022, https://doi.org/10.5194/bg-19-2007-2022, 2022
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Estuaries can significantly alter nutrient loads before reaching coastal waters. Our study of the heavily managed Ems estuary (Northern Germany) reveals three zones of nitrogen turnover along the estuary with water-column denitrification in the most upstream hyper-turbid part, nitrate production in the middle reaches and mixing/nitrate uptake in the North Sea. Suspended particulate matter was the overarching control on nitrogen cycling in the hyper-turbid estuary.
Wiley Evans, Geoffrey T. Lebon, Christen D. Harrington, Yuichiro Takeshita, and Allison Bidlack
Biogeosciences, 19, 1277–1301, https://doi.org/10.5194/bg-19-1277-2022, https://doi.org/10.5194/bg-19-1277-2022, 2022
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Information on the marine carbon dioxide system along the northeast Pacific Inside Passage has been limited. To address this gap, we instrumented an Alaskan ferry in order to characterize the marine carbon dioxide system in this region. Data over a 2-year period were used to assess drivers of the observed variability, identify the timing of severe conditions, and assess the extent of contemporary ocean acidification as well as future levels consistent with a 1.5 °C warmer climate.
Melissa Ward, Tye L. Kindinger, Heidi K. Hirsh, Tessa M. Hill, Brittany M. Jellison, Sarah Lummis, Emily B. Rivest, George G. Waldbusser, Brian Gaylord, and Kristy J. Kroeker
Biogeosciences, 19, 689–699, https://doi.org/10.5194/bg-19-689-2022, https://doi.org/10.5194/bg-19-689-2022, 2022
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Here, we synthesize the results from 62 studies reporting in situ rates of seagrass metabolism to highlight spatial and temporal variability in oxygen fluxes and inform efforts to use seagrass to mitigate ocean acidification. Our analyses suggest seagrass meadows are generally autotrophic and variable in space and time, and the effects on seawater oxygen are relatively small in magnitude.
Tianfei Xue, Ivy Frenger, A. E. Friederike Prowe, Yonss Saranga José, and Andreas Oschlies
Biogeosciences, 19, 455–475, https://doi.org/10.5194/bg-19-455-2022, https://doi.org/10.5194/bg-19-455-2022, 2022
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The Peruvian system supports 10 % of the world's fishing yield. In the Peruvian system, wind and earth’s rotation bring cold, nutrient-rich water to the surface and allow phytoplankton to grow. But observations show that it grows worse at high upwelling. Using a model, we find that high upwelling happens when air mixes the water the most. Then phytoplankton is diluted and grows slowly due to low light and cool upwelled water. This study helps to estimate how it might change in a warming climate.
Shao-Min Chen, Ulf Riebesell, Kai G. Schulz, Elisabeth von der Esch, Eric P. Achterberg, and Lennart T. Bach
Biogeosciences, 19, 295–312, https://doi.org/10.5194/bg-19-295-2022, https://doi.org/10.5194/bg-19-295-2022, 2022
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Oxygen minimum zones in the ocean are characterized by enhanced carbon dioxide (CO2) levels and are being further acidified by increasing anthropogenic atmospheric CO2. Here we report CO2 system measurements in a mesocosm study offshore Peru during a rare coastal El Niño event to investigate how CO2 dynamics may respond to ongoing ocean deoxygenation. Our observations show that nitrogen limitation, productivity, and plankton community shift play an important role in driving the CO2 dynamics.
Paula Maria Salgado-Hernanz, Aurore Regaudie-de-Gioux, David Antoine, and Gotzon Basterretxea
Biogeosciences, 19, 47–69, https://doi.org/10.5194/bg-19-47-2022, https://doi.org/10.5194/bg-19-47-2022, 2022
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For the first time, this study presents the characteristics of primary production in coastal regions of the Mediterranean Sea based on satellite-borne observations for the period 2002–2016. The study concludes that there are significant spatial and temporal variations among different regions. Quantifying primary production is of special importance in the marine food web and in the sequestration of carbon dioxide from the atmosphere to the deep waters.
Samu Elovaara, Eeva Eronen-Rasimus, Eero Asmala, Tobias Tamelander, and Hermanni Kaartokallio
Biogeosciences, 18, 6589–6616, https://doi.org/10.5194/bg-18-6589-2021, https://doi.org/10.5194/bg-18-6589-2021, 2021
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Dissolved organic matter (DOM) is a significant carbon pool in the marine environment. The composition of the DOM pool, as well as its interaction with microbes, is complex, yet understanding it is important for understanding global carbon cycling. This study shows that two phytoplankton species have different effects on the composition of the DOM pool and, through the DOM they produce, on the ensuing microbial community. These communities in turn have different effects on DOM composition.
Yuan Dong, Qian P. Li, Zhengchao Wu, Yiping Shuai, Zijia Liu, Zaiming Ge, Weiwen Zhou, and Yinchao Chen
Biogeosciences, 18, 6423–6434, https://doi.org/10.5194/bg-18-6423-2021, https://doi.org/10.5194/bg-18-6423-2021, 2021
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Temporal change of plankton growth and grazing are less known in the coastal ocean, not to mention the relevant controlling mechanisms. Here, we performed monthly size-specific dilution experiments outside a eutrophic estuary over a 1-year cycle. Phytoplankton growth was correlated to nutrients and grazing mortality to total chlorophyll a. A selective grazing on small cells may be important for maintaining high abundance of large-chain-forming diatoms in this eutrophic system.
Kiefer O. Forsch, Lisa Hahn-Woernle, Robert M. Sherrell, Vincent J. Roccanova, Kaixuan Bu, David Burdige, Maria Vernet, and Katherine A. Barbeau
Biogeosciences, 18, 6349–6375, https://doi.org/10.5194/bg-18-6349-2021, https://doi.org/10.5194/bg-18-6349-2021, 2021
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We show that for an unperturbed cold western Antarctic Peninsula fjord, the seasonality of iron and manganese is linked to the dispersal of metal-rich meltwater sources. Geochemical measurements of trace metals in meltwaters, porewaters, and seawater, collected during two expeditions, showed a seasonal cycle of distinct sources. Finally, model results revealed that the dispersal of surface meltwater and meltwater plumes originating from under the glacier is sensitive to katabatic wind events.
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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