Articles | Volume 19, issue 14
https://doi.org/10.5194/bg-19-3469-2022
© Author(s) 2022. 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-19-3469-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
27 Jul 2022
Research article |
| 27 Jul 2022
| 27 Jul 2022
Interannual variabilities, long-term trends, and regulating factors of low-oxygen conditions in the coastal waters off Hong Kong
Zheng Chen
School of Environmental Science and Engineering, Sun Yat-sen
University, Guangzhou, 510275, China
Department of Oceanography, Dalhousie University, Halifax, Nova
Scotia, B3H 4R2, Canada
Chuang Xu
Center for Water Resources and Environment, Sun Yat-sen University,
Guangzhou, 510275, China
Zhongren Zhang
School of Environmental Science and Engineering, Sun Yat-sen
University, Guangzhou, 510275, China
Guangdong Zhihuan Innovative Environmental Technology Co., Ltd.,
Guangzhou, 510030, China
Shiyu Li
School of Environmental Science and Engineering, Sun Yat-sen
University, Guangzhou, 510275, China
Jiatang Hu
CORRESPONDING AUTHOR
School of Environmental Science and Engineering, Sun Yat-sen
University, Guangzhou, 510275, China
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai),
Zhuhai, 519000, China
Related authors
No articles found.
Jiatang Hu, Zhongren Zhang, Bin Wang, and Jia Huang
Biogeosciences, 18, 5247–5264, https://doi.org/10.5194/bg-18-5247-2021, https://doi.org/10.5194/bg-18-5247-2021, 2021
Short summary
Short summary
In situ observations over 42 years were used to explore the long-term changes to low-oxygen conditions in the Pearl River estuary. Apparent expansion of the low-oxygen conditions in summer was identified, primarily due to the combined effects of increased anthropogenic inputs and decreased sediment load. Large areas of severe low-oxygen events were also observed in early autumn and were formed by distinct mechanisms. The estuary seems to be growing into a seasonal, estuary-wide hypoxic zone.
Bin Wang, Katja Fennel, and Liuqian Yu
Ocean Sci., 17, 1141–1156, https://doi.org/10.5194/os-17-1141-2021, https://doi.org/10.5194/os-17-1141-2021, 2021
Short summary
Short summary
We demonstrate that even sparse BGC-Argo profiles can substantially improve biogeochemical prediction via a priori model tuning. By assimilating satellite surface chlorophyll and physical observations, subsurface distributions of physical properties and nutrients were improved immediately. The improvement of subsurface chlorophyll was modest initially but was greatly enhanced after adjusting the parameterization for light attenuation through further a priori tuning.
Bin Wang, Katja Fennel, Liuqian Yu, and Christopher Gordon
Biogeosciences, 17, 4059–4074, https://doi.org/10.5194/bg-17-4059-2020, https://doi.org/10.5194/bg-17-4059-2020, 2020
Short summary
Short summary
We assess trade-offs between different types of biological observations, specifically satellite ocean color and BGC-Argo profiles and the benefits of combining both for optimizing a biogeochemical model of the Gulf of Mexico. Using all available observations leads to significant improvements in observed and unobserved variables (including primary production and C export). Our results highlight the significant benefits of BGC-Argo measurements for biogeochemical model optimization and validation.
Liuqian Yu, Katja Fennel, Bin Wang, Arnaud Laurent, Keith R. Thompson, and Lynn K. Shay
Ocean Sci., 15, 1801–1814, https://doi.org/10.5194/os-15-1801-2019, https://doi.org/10.5194/os-15-1801-2019, 2019
Short summary
Short summary
We present a first direct comparison of nonidentical versus identical twin approaches for an ocean data assimilation system. We show that the identical twin approach overestimates the value of assimilating satellite observations and undervalues the benefit of assimilating temperature and salinity profiles. Misleading assessments such as undervaluing the impact of observational assets are problematic and can lead to misguided decisions on balancing investments among different observing assets.
Bin Wang, Jiatang Hu, Shiyu Li, Liuqian Yu, and Jia Huang
Biogeosciences, 15, 6105–6125, https://doi.org/10.5194/bg-15-6105-2018, https://doi.org/10.5194/bg-15-6105-2018, 2018
Short summary
Short summary
A physical–biogeochemical model was applied to study the response of hypoxia and oxygen dynamics to different riverine inputs. Results showed that the hypoxia in the Pearl River estuary was most sensitive to riverine inputs of POC, followed by DO and nutrients. This study also highlighted the significance of re-aeration for its buffering effects; i.e. the re-aeration responded rapidly to the perturbations of riverine inputs and in turn moderated the DO changes impacted by these perturbations.
Bin Wang, Jiatang Hu, Shiyu Li, and Dehong Liu
Biogeosciences, 14, 2979–2999, https://doi.org/10.5194/bg-14-2979-2017, https://doi.org/10.5194/bg-14-2979-2017, 2017
Short summary
Short summary
We proposed a novel method named the physical modulation method to quantify the contributions of boundary conditions, the source and sink processes occurring in local and adjacent waters to DO conditions. A mass balance analysis of DO based on the physical modulation method indicated that the DO conditions were mainly controlled by source and sink processes, among which the sediment oxygen demand and re-aeration were two main processes controlling the spatial extent and the duration of hypoxia.
Related subject area
Biogeochemistry: Coastal Ocean
Technical note: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project (OAEPIIP)
Estimates of carbon sequestration potential in an expanding Arctic fjord (Hornsund, Svalbard) affected by dark plumes of glacial meltwater
An assessment of ocean alkalinity enhancement using aqueous hydroxides: kinetics, efficiency, and precipitation thresholds
Dissolved nitric oxide in the lower Elbe Estuary and the Port of Hamburg area
Variable contribution of wastewater treatment plant effluents to downstream nitrous oxide concentrations and emissions
Distribution of nutrients and dissolved organic matter in a eutrophic equatorial estuary: the Johor River and the East Johor Strait
Investigating the effect of silicate- and calcium-based ocean alkalinity enhancement on diatom silicification
Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment
Quantification and mitigation of bottom-trawling impacts on sedimentary organic carbon stocks in the North Sea
Influence of ocean alkalinity enhancement with olivine or steel slag on a coastal plankton community in Tasmania
Multi-model comparison of trends and controls of near-bed oxygen concentration on the northwest European continental shelf under climate change
Picoplanktonic methane production in eutrophic surface waters
Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
Hypoxia also occurs in small highly turbid estuaries: the example of the Charente (Bay of Biscay)
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
Oceanographic processes driving low-oxygen conditions inside Patagonian fjords
Above- and belowground plant mercury dynamics in a salt marsh estuary in Massachusetts, USA
Variability and drivers of carbonate chemistry at shellfish aquaculture sites in the Salish Sea, British Columbia
Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters
Insights into carbonate environmental conditions in the Chukchi Sea
UAV approaches for improved mapping of vegetation cover and estimation of carbon storage of small saltmarshes: examples from Loch Fleet, northeast Scotland
Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
Marine anoxia initiates giant sulfur-oxidizing bacterial mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland
Riverine nutrient impact on global ocean nitrogen cycle feedbacks and marine primary production in an Earth System Model
The Northeast Greenland shelf as a late-summer CO2 source to the atmosphere
Uncertainty in the evolution of northwestern North Atlantic circulation leads to diverging biogeochemical projections
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
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
Estuarine flocculation dynamics of organic carbon and metals from boreal acid sulfate soils
Drivers of particle sinking velocities in the Peruvian upwelling system
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
High metabolism and periodic hypoxia associated with drifting macrophyte detritus in the shallow subtidal Baltic Sea
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
Spatio-temporal distribution, photoreactivity and environmental control of dissolved organic matter in the sea-surface microlayer of the eastern marginal seas of China
Metabolic alkalinity release from large port facilities (Hamburg, Germany) and impact on coastal carbon storage
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
We measured nutrients and dissolved organic matter for 1 year in a eutrophic tropical estuary to understand their sources and cycling. Our data show that the dissolved organic matter originates partly from land and partly from microbial processes in the water. Internal recycling is likely important for maintaining high nutrient concentrations, and we found that there is often excess nitrogen compared to silicon and phosphorus. Our data help to explain how eutrophication persists in this system.
Aaron Ferderer, Kai G. Schulz, Ulf Riebesell, Kirralee G. Baker, Zanna Chase, and Lennart T. Bach
Biogeosciences, 21, 2777–2794, https://doi.org/10.5194/bg-21-2777-2024, https://doi.org/10.5194/bg-21-2777-2024, 2024
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
Oxygen (O2) is a key indicator of ocean health. The risk of O2 loss in the productive coastal/continental slope regions is increasing. Autonomous underwater vehicles equipped with O2 optodes provide lots of data but have problems resolving strong vertical O2 changes. Here we show how to overcome this and calculate how much O2 is supplied to the low-O2 bottom waters via mixing. Bursts in mixing supply nearly all of the O2 to bottom waters in autumn, stopping them reaching ecologically low levels.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
Miriam Tivig, David Peter Keller, and Andreas Oschlies
EGUsphere, https://doi.org/10.5194/egusphere-2024-258, https://doi.org/10.5194/egusphere-2024-258, 2024
Short summary
Short summary
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 increase primary production rates.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Michelle Holding, and Søren Rysgaard
EGUsphere, https://doi.org/10.5194/egusphere-2024-6, https://doi.org/10.5194/egusphere-2024-6, 2024
Short summary
Short summary
For this work we measured the chemistry of seawater from bottles obtained from different depths, lon- and latitudes 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 and discuss what variables may be related to such changes.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
Seawater naturally contains trace metals such as Mo and U, which accumulate under low oxygen conditions on the seafloor. Previous studies have used sediment Mo and U contents as an archive of changing oxygen concentrations in coastal waters. Here we show that in fjords the use of Mo and U for this purpose may be impaired by additional processes. Our findings have implications for the reliable use of Mo and U to reconstruct oxygen changes in fjords.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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.
Cited articles
Bordovskiy, O. K.: Sources of organic matter in marine basins, Mar.
Geol., 3, 5–31, https://doi.org/10.1016/0025-3227(65)90003-4,
1965.
Breitburg, D., Levin, L., Oschlies, A., Grégoire, M., Chavez, F.,
Conley, D., Garcon, V., Gilbert, D., Gutiérrez, D., Isensee, K.,
Jacinto, G., Limburg, K., Montes, I., Naqvi, S. W. A., Pitcher, G.,
Rabalais, N., Roman, M., Rose, K., Seibel, B., and Zhang, J.: Declining
oxygen in the global ocean and coastal waters, Science,
359, 1–13, https://doi.org/10.1126/science.aam7240, 2018.
Jolliffe, I. T. and Cadima, J.: Principal component analysis: a review and recent developments, Philos. T. R. Soc. Math. Phys. Eng. Sci., 374, 20150202, https://doi.org/10.1098/rsta.2015.0202, 2016.
Chen, J., Wang, Z., Tam, C.-Y., Lau, N.-C., Lau, D.-S. D., and Mok, H.-Y.:
Impacts of climate change on tropical cyclones and induced storm surges in
the Pearl River Delta region using pseudo-global-warming method, Scientific
Reports, 10, 1965, https://doi.org/10.1038/s41598-020-58824-8, 2020.
Chen, Z.: The long-term monthly discharge data of hydrological stations in the Pearl River during 1994–2018, Zenodo [data set], https://doi.org/10.5281/zenodo.6859871, 2022.
Chi, L., Song, X., Yuan, Y., Wang, W., Cao, X., Wu, Z., and Yu, Z.: Main
factors dominating the development, formation and dissipation of hypoxia off
the Changjiang Estuary (CE) and its adjacent waters, China, Environ.
Pollut., 265, 115066, https://doi.org/10.1016/j.envpol.2020.115066, 2020.
Conley, D., Carstensen, J., Aigars, J., Axe, P., Bonsdorff, E., Eremina, T.,
Haahti, B.-M., Humborg, C., Jonsson, P., Kotta, J., Lännegren, C.,
Larsson, U., Maximov, A., Medina, M., Lysiak-Pastuszak, E.,
Remeikaitė-Nikienė, N., Walve, J., Wilhelms, S., and Zillén, L.:
Hypoxia is increasing in the coastal zone of the Baltic Sea, Environ.
Sci. Technol., 45, 6777–6783, https://doi.org/10.1021/es201212r, 2011.
Cui, Y., Wu, J. X., Ren, J., and Xu, J.: Physical dynamics structures and
oxygen budget of summer hypoxia in the Pearl River Estuary: Dynamical
structures and oxygen budget of hypoxia, Limnol. Oceanogr., 64,
131–148, https://doi.org/10.1002/lno.11025, 2018.
Dai, M., Zhai, W., Cai, W.-J., Callahan, J., Huang, B., Shang, S., Huang,
T., Li, X., Lu, Z., Chen, W., and Chen, Z.: Effects of an estuarine
plume-associated bloom on the carbonate system in the lower reaches of the
Pearl River estuary and the coastal zone of the northern South China Sea,
Cont. Shelf Res., 28, 1416–1423, https://doi.org/10.1016/j.csr.2007.04.018, 2008.
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.
Feng, Y., DiMarco, S. F., and Jackson, G. A.: Relative role of wind forcing
and riverine nutrient input on the extent of hypoxia in the northern Gulf of
Mexico, Geophys. Res. Lett., 39, L09601, https://doi.org/10.1029/2012GL051192, 2012.
Feng, Y., Fennel, K., Jackson, G. A., DiMarco, S. F., and Hetland, R. D.: A
model study of the response of hypoxia to upwelling-favorable wind on the
northern Gulf of Mexico shelf, J. Marine Syst., 131, 63–73, https://doi.org/10.1016/j.jmarsys.2013.11.009, 2014.
Fennel, K. and Testa, J.: Biogeochemical Controls on Coastal Hypoxia, Annu. Rev. Mar. Sci., 11, 105–130, https://doi.org/10.1146/annurev-marine-010318-095138, 2018.
Forrest, D., Hetland, R., and Dimarco, S.: Multivariable statistical
regression models of the areal extent of hypoxia over the Texas-Louisiana
Shelf, Environ. Res. Lett., 6, 045002,
https://doi.org/10.1088/1748-9326/6/4/045002, 2011.
Gao, N., Ma, Y., Zhao, M., Zhang, L., Zhan, H., and He, Q.: Quantile
Analysis of Long-Term Trends of Near-Surface Chlorophyll-a in the Pearl
River Plume, Water, 12, 1662, https://doi.org/10.3390/w12061662, 2020.
Hu, J., Zhang, Z., Wang, B., and Huang, J.: Long-term spatiotemporal variations in and expansion of low-oxygen conditions in the Pearl River estuary: a study synthesizing observations during 1976–2017, Biogeosciences, 18, 5247–5264, https://doi.org/10.5194/bg-18-5247-2021, 2021.
Justić, D., Rabalais, N., and Turner, R.: Simulated Responses of the
Gulf of Mexico Hypoxia to Variations in Climate and Anthropogenic Nutrient
Loading, J. Marine Syst., 42, 115–126,
https://doi.org/10.1016/S0924-7963(03)00070-8, 2003.
Laurent, A. and Fennel, K.: Time-evolving, spatially explicit forecasts of
the Northern Gulf of Mexico hypoxic zone, Environ. Sci.
Technol., 53, 14449–14458, https://doi.org/10.1021/acs.est.9b05790, 2019.
Li, D., Gan, J., Hui, C., Yu, L., Liu, Z., Lu, Z., Kao, S.-J., and Dai, M.:
Spatiotemporal development and dissipation of hypoxia induced by variable
wind-driven shelf circulation off the Pearl River Estuary: Observational and
modeling studies, J. Geophys. Res.-Oceans, 126,
e2020JC016700, https://doi.org/10.1029/2020JC016700, 2021.
Li, G., Liu, J., Diao, Z., Jiang, X., Li, J., Ke, Z., Shen, P., Ren, L.,
Huang, L., and Tan, Y.: Subsurface low dissolved oxygen occurred at fresh-
and saline-water intersection of the Pearl River estuary during the summer
period, Mar. Pollut. Bull., 126, 585–591, https://doi.org/10.1016/j.marpolbul.2017.09.061, 2018.
Li, M., Lee, Y. J., Testa, J. M., Li, Y., Ni, W., Kemp, W. M., and Di Toro,
D. M.: What drives interannual variability of hypoxia in Chesapeake Bay:
Climate forcing versus nutrient loading?, Geophys. Res. Lett., 43,
2127–2134, https://doi.org/10.1002/2015GL067334, 2016.
Li, X., Lu, C., Zhang, Y., Zhao, H., Wang, J., Liu, H., and Yin, K.: Low
dissolved oxygen in the Pearl River estuary in summer: Long-term
spatio-temporal patterns, trends, and regulating factors, Mar. Pollut. Bull., 151, 110814, https://doi.org/10.1016/j.marpolbul.2019.110814, 2020.
Ludsin, S. A., Zhang, X., Brandt, S. B., Roman, M. R., Boicourt, W. C.,
Mason, D. M., and Costantini, M.: Hypoxia-avoidance by planktivorous fish in
Chesapeake Bay: Implications for food web interactions and fish recruitment,
J. Exp. Mar. Biol. Ecol., 381, S121–S131,
https://doi.org/10.1016/j.jembe.2009.07.016, 2009.
Luo, L., Li, S., and Wang, D.: Hypoxia in the Pearl River Estuary, the South
China Sea, in July 1999, Aquat. Ecosyst. Health, 12,
418–428, https://doi.org/10.1080/14634980903352407, 2009.
Lu, Z., Gan, J., Dai, M., Liu, H., and Zhao, X.: Joint effects of extrinsic
biophysical fluxes and intrinsic hydrodynamics on the formation of hypoxia
west off the Pearl River Estuary, J. Geophys. Res.-Oceans,
123, 6241–6259, 2018.
Meier, H. E. M., Eilola, K., Almroth-Rosell, E., Schimanke, S., Kniebusch,
M., Höglund, A., Pemberton, P., Liu, Y., Väli, G., and Saraiva, S.:
Disentangling the impact of nutrient load and climate changes on Baltic Sea
hypoxia and eutrophication since 1850, Clim. Dynam., 53, 1145–1166,
https://doi.org/10.1007/s00382-018-4296-y, 2019.
Meyers, P. A. and Ishiwatari, R.: Lacustrine organic geochemistry – an
overview of indicators of organic matter sources and diagenesis in lake
sediments, Org. Geochem., 20, 867–900, https://doi.org/10.1016/0146-6380(93)90100-P, 1993.
Murphy, R., Kemp, W., and Ball, W.: Long-Term Trends in Chesapeake Bay
Seasonal Hypoxia, Stratification, and Nutrient Loading, Estuar.
Coast., 34, 1293–1309, https://doi.org/10.1007/s12237-011-9413-7, 2011.
Ni, W., Li, M., Ross, A. C., and Najjar, R. G.: Large Projected Decline in
Dissolved Oxygen in a Eutrophic Estuary Due to Climate Change, J. Geophys. Res.-Oceans, 124, 8271–8289, https://doi.org/10.1029/2019JC015274, 2019.
Ni, W., Li, M., and Testa, J. M.: Discerning effects of warming, sea level
rise and nutrient management on long-term hypoxia trends in Chesapeake Bay,
Sci. Total Environ., 737, 139717, https://doi.org/10.1016/j.scitotenv.2020.139717, 2020.
Obenour, D., Scavia, D., Rabalais, N., Turner, R., and Michalak, A.:
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.
Qian, W., Gan, J., Liu, J., He, B., Lu, Z., Guo, X., Wang, D., Guo, L.,
Huang, T., and Dai, M.: Current status of emerging hypoxia in a eutrophic
estuary: The lower reach of the Pearl River Estuary, China, Estuar. Coast. Shelf S., 205, 58–67, https://doi.org/10.1016/j.ecss.2018.03.004, 2018.
Rabalais, N., Turner, R., and Boesch, D.: A brief summary of hypoxia on the
northern Gulf of Mexico continental shelf: 1985–1988, Geo. Soc. S. P., 58, 35–47, https://doi.org/10.1144/GSL.SP.1991.058.01.03,
1991.
Rabalais, N. N., Díaz, R. J., Levin, L. A., Turner, R. E., Gilbert, D., and Zhang, J.: Dynamics and distribution of natural and human-caused hypoxia, Biogeosciences, 7, 585–619, https://doi.org/10.5194/bg-7-585-2010, 2010.
Rabouille, C., Conley, D. J., Dai, M. H., Cai, W. J., Chen, C. T. A.,
Lansard, B., Green, R., Yin, K., Harrison, P. J., Dagg, M., and McKee, B.:
Comparison of hypoxia among four river-dominated ocean margins: The
Changjiang (Yangtze), Mississippi, Pearl, and Rhône rivers, Cont. Shelf Res., 28, 1527–1537, https://doi.org/10.1016/j.csr.2008.01.020, 2008.
Raymond, P. and Bauer, J.: Use of 14C and 13C natural abundances for
evaluating riverine, estuarine, and coastal DOC and POC sources and cycling:
A review and synthesis, Org. Geochem., 32, 469–485,
https://doi.org/10.1016/S0146-6380(00)00190-X, 2001.
Shi, Z., Liu, K., Zhang, S., Xu, H., and Liu, H.: Spatial distributions of
mesozooplankton biomass, community composition and grazing impact in
association with hypoxia in the Pearl River Estuary, Estuar. Coast.
Shelf Sci., 225, 106237, https://doi.org/10.1016/j.ecss.2019.05.019, 2019.
Su, J., Dai, M., He, B., Wang, L., Gan, J., Guo, X., Zhao, H., and Yu, F.: Tracing the origin of the oxygen-consuming organic matter in the hypoxic zone in a large eutrophic estuary: the lower reach of the Pearl River Estuary, China, Biogeosciences, 14, 4085–4099, https://doi.org/10.5194/bg-14-4085-2017, 2017.
Sun, J., Lin, B., Li, K., and Jiang, G.: A modelling study of residence time
and exposure time in the Pearl River Estuary, China, J.
Hydro-Environ. Res., 8, 281–291, https://doi.org/10.1016/j.jher.2013.06.003, 2014.
Testa, J., Murphy, R., Brady, D., and Kemp, W.: Nutrient- and
Climate-Induced Shifts in the Phenology of Linked Biogeochemical Cycles in a
Temperate Estuary, Front. Mar. Sci., 5, 114,
https://doi.org/10.3389/fmars.2018.00114, 2018.
Wang, B., Hu, J., Li, S., and Liu, D.: A numerical analysis of biogeochemical controls with physical modulation on hypoxia during summer in the Pearl River estuary, Biogeosciences, 14, 2979–2999, https://doi.org/10.5194/bg-14-2979-2017, 2017.
Wang, B., Hu, J., Li, S., Yu, L., and Huang, J.: Impacts of anthropogenic inputs on hypoxia and oxygen dynamics in the Pearl River estuary, Biogeosciences, 15, 6105–6125, https://doi.org/10.5194/bg-15-6105-2018, 2018.
Wang, K., Cai, W.-J., Chen, J., Kirchman, D., Wang, B., Fan, W., and Huang,
D.: Climate and Human-Driven Variability of Summer Hypoxia on a Large
River-Dominated Shelf as Revealed by a Hypoxia Index, Front. Mar.
Sci., 8, 634184, https://doi.org/10.3389/fmars.2021.634184, 2021.
Wang, P., Wang, H., and Linker, L.: Relative Importance of Nutrient Load and
Wind on Regulating Interannual Summer Hypoxia in the Chesapeake Bay,
Estuaries Coasts, 38, 1048–1061, https://doi.org/10.1007/s12237-014-9867-5, 2015.
Wen, G., Liang, Z., Xu, X., Cao, R., Wan, Q., Ji, G., Lin, W., Wang, J.,
Yang, J., and Huang, T.: Inactivation of fungal spores in water using ozone:
Kinetics, influencing factors and mechanisms, Water Res., 185, 116218,
https://doi.org/10.1016/j.watres.2020.116218, 2020.
Xu, C., Gong, L., Tong, J., Chen, D., and Singh, V.: Analysis of spatial
distribution and temporal trend of reference ET in Changjiang catchments,
J. Hydrol., 327, 81–93, https://doi.org/10.1016/j.jhydrol.2005.11.029, 2006.
Xu, J., Yin, K. D., Liu, H., Lee, J., Anderson, D., Ho, A., and Harrison,
P.: A comparison of eutrophication impacts in two harbours in Hong Kong with
different hydrodynamics, J. Marine Syst., 83, 276–286, https://doi.org/10.1016/j.jmarsys.2010.04.002, 2010.
Yin, K., Lin, Z., and Ke, Z.: Temporal and spatial distribution of dissolved
oxygen in the Pearl River Estuary and adjacent coastal waters, Cont. Shelf Res., 24, 1935–1948, https://doi.org/10.1016/j.csr.2004.06.017, 2004.
Yu, L., Fennel, K., and Laurent, A.: A modeling study of physical controls
on hypoxia generation in the northern Gulf of Mexico, J. Geophys. Res.-Oceans, 120, 5019–5039, https://doi.org/10.1002/2014JC010634, 2015.
Yu, L., Gan, J., Dai, M., Hui, C., Lu, X., and Li, D.: Modeling the role of
riverine organic matter in hypoxia formation within the coastal transition
zone off the Pearl River Estuary, Limnol. Oceanogr., 66, 452–468,
https://doi.org/10.1002/lno.11616, 2021.
Zhang, H. and Li, S.: Effects of physical and biochemical processes on the
dissolved oxygen budget for the Pearl River Estuary during summer, J. Marine Syst., 79, 65–88, https://doi.org/10.1016/j.jmarsys.2009.07.002, 2010.
Zhang, T., Chen, Y., and Paw, U. K. T.: Quantifying the impact of climate variables
on reference evapotranspiration in Pearl River Basin, China, Hydrolog.
Sci. J., 64, 1–13, https://doi.org/10.1080/02626667.2019.1662021, 2019.
Zhang, W., Moriarty, J. M., Wu, H., and Feng, Y.: Response of bottom hypoxia
off the Changjiang River Estuary to multiple factors: A numerical study,
Ocean Model., 159, 101751, https://doi.org/10.1016/j.ocemod.2021.101751, 2021.
Zhang, X., Ren, Y., Yin, J., Lin, Z., and Zheng, D.: Spatial and temporal
variation patterns of reference evapotranspiration across the
Qinghai-Tibetan Plateau during 1971–2004, J. Geophys. Res, 114, D15105, https://doi.org/10.1029/2009JD011753, 2009.
Zhou, Y., Scavia, D., and Michalak, A.: Nutrient loading and meteorological
conditions explain interannual variability of hypoxia in Chesapeake Bay,
Limnol. Oceanogr., 59, 373–384, https://doi.org/10.4319/lo.2014.59.2.0373, 2014.
Zhu, Z., Zhang, J., Wu, Y., Zhang, Y., Lin, J., and Liu, S.: 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.
Short summary
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.
Deterioration of low-oxygen conditions in the coastal waters off Hong Kong was revealed by...
Altmetrics
Final-revised paper
Preprint