Articles | Volume 15, issue 4
https://doi.org/10.5194/bg-15-1093-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/bg-15-1093-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 Feb 2018
Research article |
| 22 Feb 2018
| 22 Feb 2018
Carbon dynamics and CO2 and CH4 outgassing in the Mekong delta
Alberto V. Borges
CORRESPONDING AUTHOR
Chemical Oceanography Unit, University of Liège, 4000 Liège,
Belgium
Gwenaël Abril
Programa de Geoquímica, Universidade Federal Fluminense,
24020015, Niterói, Brazil
Laboratoire Environnements et Paléoenvironnements Océaniques
et Continentaux, CNRS, Université de Bordeaux, 33405, Talence, France
Steven Bouillon
Department of Earth and Environmental Sciences, KU Leuven, 3001
Leuven, Belgium
Related authors
Vao Fenotiana Razanamahandry, Alberto Borges, Liesa Brosens, Cedric Morana, Tantely Razafimbelo, Tovonarivo Rafolisy, Gerard Govers, and Steven Bouillon
EGUsphere, https://doi.org/10.5194/egusphere-2024-2213, https://doi.org/10.5194/egusphere-2024-2213, 2024
Short summary
Short summary
A comprehensive survey of the biogeochemistry of the lake Alaotra system showed that the lake and surrounding wetlands acted as a substantial source of new organic carbon (OC), which was exported downstream. Marsh vegetation is the main source of dissolved OC, while phytoplankton contributes to particulate OC pool. The biogeochemical functioning of Lake Alaotra differs from most East African lakes studied, likely due to its large surface area, shallow water depth, and surrounding wetlands.
Thomas Bauduin, Nathalie Gypens, and Alberto V. Borges
EGUsphere, https://doi.org/10.5194/egusphere-2024-1315, https://doi.org/10.5194/egusphere-2024-1315, 2024
Short summary
Short summary
Greenhouse gases (GHG) emissions from ponds can vary depending on the state of ponds (clear-water with macrophytes or turbid-water with phytoplankton). We studied CO2, CH4, and N2O emissions in clear and turbid urban ponds (June 2021 to December 2023) in Brussels. We observed seasonal differences in methanogenesis pathways, in CH4 emissions between clear and turbid ponds, and annual differences in total emissions of GHG, likely from intense El Niño event in 2023.
Christian Lønborg, Cátia Carreira, Gwenaël Abril, Susana Agustí, Valentina Amaral, Agneta Andersson, Javier Arístegui, Punyasloke Bhadury, Mariana B. Bif, Alberto V. Borges, Steven Bouillon, Maria Ll. Calleja, Luiz C. Cotovicz Jr., Stefano Cozzi, Maryló Doval, Carlos M. Duarte, Bradley Eyre, Cédric G. Fichot, E. Elena García-Martín, Alexandra Garzon-Garcia, Michele Giani, Rafael Gonçalves-Araujo, Renee Gruber, Dennis A. Hansell, Fuminori Hashihama, Ding He, Johnna M. Holding, William R. Hunter, J. Severino P. Ibánhez, Valeria Ibello, Shan Jiang, Guebuem Kim, Katja Klun, Piotr Kowalczuk, Atsushi Kubo, Choon-Weng Lee, Cláudia B. Lopes, Federica Maggioni, Paolo Magni, Celia Marrase, Patrick Martin, S. Leigh McCallister, Roisin McCallum, Patricia M. Medeiros, Xosé Anxelu G. Morán, Frank E. Muller-Karger, Allison Myers-Pigg, Marit Norli, Joanne M. Oakes, Helena Osterholz, Hyekyung Park, Maria Lund Paulsen, Judith A. Rosentreter, Jeff D. Ross, Digna Rueda-Roa, Chiara Santinelli, Yuan Shen, Eva Teira, Tinkara Tinta, Guenther Uher, Masahide Wakita, Nicholas Ward, Kenta Watanabe, Yu Xin, Youhei Yamashita, Liyang Yang, Jacob Yeo, Huamao Yuan, Qiang Zheng, and Xosé Antón Álvarez-Salgado
Earth Syst. Sci. Data, 16, 1107–1119, https://doi.org/10.5194/essd-16-1107-2024, https://doi.org/10.5194/essd-16-1107-2024, 2024
Short summary
Short summary
In this paper, we present the first edition of a global database compiling previously published and unpublished measurements of dissolved organic matter (DOM) collected in coastal waters (CoastDOM v1). Overall, the CoastDOM v1 dataset will be useful to identify global spatial and temporal patterns and to facilitate reuse in studies aimed at better characterizing local biogeochemical processes and identifying a baseline for modelling future changes in coastal waters.
Samuel T. Wilson, Alia N. Al-Haj, Annie Bourbonnais, Claudia Frey, Robinson W. Fulweiler, John D. Kessler, Hannah K. Marchant, Jana Milucka, Nicholas E. Ray, Parvadha Suntharalingam, Brett F. Thornton, Robert C. Upstill-Goddard, Thomas S. Weber, Damian L. Arévalo-Martínez, Hermann W. Bange, Heather M. Benway, Daniele Bianchi, Alberto V. Borges, Bonnie X. Chang, Patrick M. Crill, Daniela A. del Valle, Laura Farías, Samantha B. Joye, Annette Kock, Jabrane Labidi, Cara C. Manning, John W. Pohlman, Gregor Rehder, Katy J. Sparrow, Philippe D. Tortell, Tina Treude, David L. Valentine, Bess B. Ward, Simon Yang, and Leonid N. Yurganov
Biogeosciences, 17, 5809–5828, https://doi.org/10.5194/bg-17-5809-2020, https://doi.org/10.5194/bg-17-5809-2020, 2020
Short summary
Short summary
The oceans are a net source of the major greenhouse gases; however there has been little coordination of oceanic methane and nitrous oxide measurements. The scientific community has recently embarked on a series of capacity-building exercises to improve the interoperability of dissolved methane and nitrous oxide measurements. This paper derives from a workshop which discussed the challenges and opportunities for oceanic methane and nitrous oxide research in the near future.
Cédric Morana, Steven Bouillon, Vimac Nolla-Ardèvol, Fleur A. E. Roland, William Okello, Jean-Pierre Descy, Angela Nankabirwa, Erina Nabafu, Dirk Springael, and Alberto V. Borges
Biogeosciences, 17, 5209–5221, https://doi.org/10.5194/bg-17-5209-2020, https://doi.org/10.5194/bg-17-5209-2020, 2020
Short summary
Short summary
A growing body of studies challenges the paradigm that methane (CH4) production occurs only under anaerobic conditions. Our field experiments revealed that oxic CH4 production is closely related to phytoplankton metabolism and is indeed a common feature in five contrasting African lakes. Nevertheless, we found that methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface.
Alberto V. Borges, François Darchambeau, Thibault Lambert, Cédric Morana, George H. Allen, Ernest Tambwe, Alfred Toengaho Sembaito, Taylor Mambo, José Nlandu Wabakhangazi, Jean-Pierre Descy, Cristian R. Teodoru, and Steven Bouillon
Biogeosciences, 16, 3801–3834, https://doi.org/10.5194/bg-16-3801-2019, https://doi.org/10.5194/bg-16-3801-2019, 2019
Short summary
Short summary
Tropical rivers might be strong sources of CO2 and CH4 to the atmosphere, although there is an enormous data gap. The origin of CO2 in lowland tropical rivers is not well characterized and can be from terra firme or from wetlands (flooded forests and aquatic macrophytes). We obtained a large field dataset of CO2, CH4 and N2O in the Congo, the second-largest river in the world, which allows us to quantity the emission of these greenhouse gases to the atmosphere and investigate their origin.
Gwenaël Abril and Alberto V. Borges
Biogeosciences, 16, 769–784, https://doi.org/10.5194/bg-16-769-2019, https://doi.org/10.5194/bg-16-769-2019, 2019
Short summary
Short summary
Based on classical concepts in ecology, and a literature survey, we highlight the importance of flooded land as a preferential source of atmospheric carbon to aquatic systems at the global scale. Studies in terrestrial and aquatic ecosystems could be reconciled by considering the occurrence of an efficient wetland CO2 pump to river systems. New methodological approaches coupling hydrology and ecology are also necessary to improve scientific knowledge on carbon fluxes at the land–water interface.
Samuel T. Wilson, Hermann W. Bange, Damian L. Arévalo-Martínez, Jonathan Barnes, Alberto V. Borges, Ian Brown, John L. Bullister, Macarena Burgos, David W. Capelle, Michael Casso, Mercedes de la Paz, Laura Farías, Lindsay Fenwick, Sara Ferrón, Gerardo Garcia, Michael Glockzin, David M. Karl, Annette Kock, Sarah Laperriere, Cliff S. Law, Cara C. Manning, Andrew Marriner, Jukka-Pekka Myllykangas, John W. Pohlman, Andrew P. Rees, Alyson E. Santoro, Philippe D. Tortell, Robert C. Upstill-Goddard, David P. Wisegarver, Gui-Ling Zhang, and Gregor Rehder
Biogeosciences, 15, 5891–5907, https://doi.org/10.5194/bg-15-5891-2018, https://doi.org/10.5194/bg-15-5891-2018, 2018
Short summary
Short summary
To determine the variability between independent measurements of dissolved methane and nitrous oxide, seawater samples were analyzed by multiple laboratories. The results revealed the influences of the different parts of the analytical process, from the initial sample collection to the calculation of the final concentrations. Recommendations are made to improve dissolved methane and nitrous oxide measurements to help preclude future analytical discrepancies between laboratories.
Trent R. Marwick, Fredrick Tamooh, Bernard Ogwoka, Alberto V. Borges, François Darchambeau, and Steven Bouillon
Biogeosciences, 15, 1683–1700, https://doi.org/10.5194/bg-15-1683-2018, https://doi.org/10.5194/bg-15-1683-2018, 2018
Short summary
Short summary
A 2-year biogeochemical record provides annual sediment and element flux estimates for the non-dammed Sabaki River, Kenya, establishing a baseline for future research in light of impending construction of the first major upstream reservoir. Over 80 % of material fluxes occur across the wet season, with annual yields comparable to the adjacent, and dammed, Tana River. Observations at low-flow periods suggest large mammalian herbivores may be vectors of terrestrial subsidies to the water column.
Naomi Geeraert, Fred O. Omengo, Fredrick Tamooh, Trent R. Marwick, Alberto V. Borges, Gerard Govers, and Steven Bouillon
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-31, https://doi.org/10.5194/bg-2017-31, 2017
Manuscript not accepted for further review
Short summary
Short summary
We observed that the relationship between the concentrations and the water discharge in the Tana River changed in wet seasons with and without flooding. Detailed sampling in those seasons is required in order to construct several rating curves and to obtain reliable flux estimates. The sediment and carbon fluxes in function of discharge will help us to asses the flux changes that can be expected when the hydrology changes due to climate change or human impact.
Thibault Lambert, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 5405–5420, https://doi.org/10.5194/bg-13-5405-2016, https://doi.org/10.5194/bg-13-5405-2016, 2016
Short summary
Short summary
This paper aims to investigate the spatial variability in dissolved organic matter (DOM) in terms of both concentration and composition in the Congo River network. Stable carbon isotopes and absorption and fluorescent properties of DOM were used as proxies for DOM composition. This study shows that DOM degradation within the Congo Basin results in the transition from aromatic to aliphatic DOM as well as the role of landscape and water residence time on this transition.
Fleur A. E. Roland, François Darchambeau, Cédric Morana, Sean A. Crowe, Bo Thamdrup, and Alberto V. Borges
Biogeosciences Discuss., https://doi.org/10.5194/bg-2016-300, https://doi.org/10.5194/bg-2016-300, 2016
Manuscript not accepted for further review
Short summary
Short summary
We studied methane consumption in a tropical Great Lake (Lake Kivu, East Africa). Lake Kivu has huge methane concentrations in its deep anoxic waters, but is a very poor emitter of methane to the atmosphere, which suppose a strong methane consumption in the water column. During this study, we put in evidence high aerobic and anaerobic consumption rates, whose relative importance varied with the season (higher aerobic rates in dry season, when the oxic compartment is wider).
Thibault Lambert, Cristian R. Teodoru, Frank C. Nyoni, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 2727–2741, https://doi.org/10.5194/bg-13-2727-2016, https://doi.org/10.5194/bg-13-2727-2016, 2016
Short summary
Short summary
This manuscript presents a detailed analysis of transport and transformation of dissolved organic matter along the Zambezi River and its largest tributary. A particular focus is put on the effects of floodplains/wetlands and reservoirs as well as low-flow vs. high-flow conditions on the longitudinal patterns in DOM concentration and composition. It is the first study to present such a detailed analysis for a whole, large river system, and in particular for a tropical river other than the Amazon.
C. Morana, F. Darchambeau, F. A. E. Roland, A. V. Borges, F. Muvundja, Z. Kelemen, P. Masilya, J.-P. Descy, and S. Bouillon
Biogeosciences, 12, 4953–4963, https://doi.org/10.5194/bg-12-4953-2015, https://doi.org/10.5194/bg-12-4953-2015, 2015
C. R. Teodoru, F. C. Nyoni, A. V. Borges, F. Darchambeau, I. Nyambe, and S. Bouillon
Biogeosciences, 12, 2431–2453, https://doi.org/10.5194/bg-12-2431-2015, https://doi.org/10.5194/bg-12-2431-2015, 2015
Short summary
Short summary
CO2 and CH4 concentrations and fluxes in the Zambezi River basin are well below the median/average values reported previously for tropical rivers, streams and reservoirs, and mainly controlled by the connectivity with floodplains and the presence of waterfalls and man-made reservoirs. The mass balance suggests that carbon transport to the ocean represents the major component (~60%) of the budget, while emissions to the atmosphere account for less than 40% of the total carbon yield.
C. Morana, A. V. Borges, F. A. E. Roland, F. Darchambeau, J.-P. Descy, and S. Bouillon
Biogeosciences, 12, 2077–2088, https://doi.org/10.5194/bg-12-2077-2015, https://doi.org/10.5194/bg-12-2077-2015, 2015
M. Hagens, C. P. Slomp, F. J. R. Meysman, D. Seitaj, J. Harlay, A. V. Borges, and J. J. Middelburg
Biogeosciences, 12, 1561–1583, https://doi.org/10.5194/bg-12-1561-2015, https://doi.org/10.5194/bg-12-1561-2015, 2015
Short summary
Short summary
This study looks at the combined impacts of hypoxia and acidification, two major environmental stressors affecting coastal systems, in a seasonally stratified basin. Here, the surface water experiences less seasonality in pH than the bottom water despite higher process rates. This is due to a substantial reduction in the acid-base buffering capacity of the bottom water as it turns hypoxic in summer. This highlights the crucial role of the buffering capacity as a modulating factor in pH dynamics.
G. Abril, S. Bouillon, F. Darchambeau, C. R. Teodoru, T. R. Marwick, F. Tamooh, F. Ochieng Omengo, N. Geeraert, L. Deirmendjian, P. Polsenaere, and A. V. Borges
Biogeosciences, 12, 67–78, https://doi.org/10.5194/bg-12-67-2015, https://doi.org/10.5194/bg-12-67-2015, 2015
Short summary
Short summary
We compared pCO2 data calculated from pH and alkalinity from those measured directly in a large array of temperate and tropical freshwaters. This revealed a large overestimation (up to 300%) of calculated pCO2 in the case of acidic and organic-rich waters, due to a contribution of organic acids anions to alkalinity and a lower buffering capacity of the carbonate system at acidic pH. Given the widespread distribution of acidic freshwaters, direct measurements of water pCO2 are encouraged.
P. Ciais, A. J. Dolman, A. Bombelli, R. Duren, A. Peregon, P. J. Rayner, C. Miller, N. Gobron, G. Kinderman, G. Marland, N. Gruber, F. Chevallier, R. J. Andres, G. Balsamo, L. Bopp, F.-M. Bréon, G. Broquet, R. Dargaville, T. J. Battin, A. Borges, H. Bovensmann, M. Buchwitz, J. Butler, J. G. Canadell, R. B. Cook, R. DeFries, R. Engelen, K. R. Gurney, C. Heinze, M. Heimann, A. Held, M. Henry, B. Law, S. Luyssaert, J. Miller, T. Moriyama, C. Moulin, R. B. Myneni, C. Nussli, M. Obersteiner, D. Ojima, Y. Pan, J.-D. Paris, S. L. Piao, B. Poulter, S. Plummer, S. Quegan, P. Raymond, M. Reichstein, L. Rivier, C. Sabine, D. Schimel, O. Tarasova, R. Valentini, R. Wang, G. van der Werf, D. Wickland, M. Williams, and C. Zehner
Biogeosciences, 11, 3547–3602, https://doi.org/10.5194/bg-11-3547-2014, https://doi.org/10.5194/bg-11-3547-2014, 2014
T. R. Marwick, F. Tamooh, B. Ogwoka, C. Teodoru, A. V. Borges, F. Darchambeau, and S. Bouillon
Biogeosciences, 11, 443–460, https://doi.org/10.5194/bg-11-443-2014, https://doi.org/10.5194/bg-11-443-2014, 2014
F. Tamooh, A. V. Borges, F. J. R. Meysman, K. Van Den Meersche, F. Dehairs, R. Merckx, and S. Bouillon
Biogeosciences, 10, 6911–6928, https://doi.org/10.5194/bg-10-6911-2013, https://doi.org/10.5194/bg-10-6911-2013, 2013
Zita Kelemen, David P. Gillikin, and Steven Bouillon
EGUsphere, https://doi.org/10.5194/egusphere-2024-2714, https://doi.org/10.5194/egusphere-2024-2714, 2024
Short summary
Short summary
We analysed the C and O stable isotope composition (δ13C, δ18O) across the growth axis of museum-archived and recent Chambardia wissmanni shells from the Oubangui River (Congo Basin) covering sections of the past ~120 years. Recent shells showed a much wider range in δ18O values compared to historical specimens, consistent with the suggestion that dry periods in the upper Congo basin are becoming more extreme in recent times; highlighting their potential to reconstruct hydroclimatic conditions.
Vao Fenotiana Razanamahandry, Alberto Borges, Liesa Brosens, Cedric Morana, Tantely Razafimbelo, Tovonarivo Rafolisy, Gerard Govers, and Steven Bouillon
EGUsphere, https://doi.org/10.5194/egusphere-2024-2213, https://doi.org/10.5194/egusphere-2024-2213, 2024
Short summary
Short summary
A comprehensive survey of the biogeochemistry of the lake Alaotra system showed that the lake and surrounding wetlands acted as a substantial source of new organic carbon (OC), which was exported downstream. Marsh vegetation is the main source of dissolved OC, while phytoplankton contributes to particulate OC pool. The biogeochemical functioning of Lake Alaotra differs from most East African lakes studied, likely due to its large surface area, shallow water depth, and surrounding wetlands.
Thomas Bauduin, Nathalie Gypens, and Alberto V. Borges
EGUsphere, https://doi.org/10.5194/egusphere-2024-1315, https://doi.org/10.5194/egusphere-2024-1315, 2024
Short summary
Short summary
Greenhouse gases (GHG) emissions from ponds can vary depending on the state of ponds (clear-water with macrophytes or turbid-water with phytoplankton). We studied CO2, CH4, and N2O emissions in clear and turbid urban ponds (June 2021 to December 2023) in Brussels. We observed seasonal differences in methanogenesis pathways, in CH4 emissions between clear and turbid ponds, and annual differences in total emissions of GHG, likely from intense El Niño event in 2023.
Christian Lønborg, Cátia Carreira, Gwenaël Abril, Susana Agustí, Valentina Amaral, Agneta Andersson, Javier Arístegui, Punyasloke Bhadury, Mariana B. Bif, Alberto V. Borges, Steven Bouillon, Maria Ll. Calleja, Luiz C. Cotovicz Jr., Stefano Cozzi, Maryló Doval, Carlos M. Duarte, Bradley Eyre, Cédric G. Fichot, E. Elena García-Martín, Alexandra Garzon-Garcia, Michele Giani, Rafael Gonçalves-Araujo, Renee Gruber, Dennis A. Hansell, Fuminori Hashihama, Ding He, Johnna M. Holding, William R. Hunter, J. Severino P. Ibánhez, Valeria Ibello, Shan Jiang, Guebuem Kim, Katja Klun, Piotr Kowalczuk, Atsushi Kubo, Choon-Weng Lee, Cláudia B. Lopes, Federica Maggioni, Paolo Magni, Celia Marrase, Patrick Martin, S. Leigh McCallister, Roisin McCallum, Patricia M. Medeiros, Xosé Anxelu G. Morán, Frank E. Muller-Karger, Allison Myers-Pigg, Marit Norli, Joanne M. Oakes, Helena Osterholz, Hyekyung Park, Maria Lund Paulsen, Judith A. Rosentreter, Jeff D. Ross, Digna Rueda-Roa, Chiara Santinelli, Yuan Shen, Eva Teira, Tinkara Tinta, Guenther Uher, Masahide Wakita, Nicholas Ward, Kenta Watanabe, Yu Xin, Youhei Yamashita, Liyang Yang, Jacob Yeo, Huamao Yuan, Qiang Zheng, and Xosé Antón Álvarez-Salgado
Earth Syst. Sci. Data, 16, 1107–1119, https://doi.org/10.5194/essd-16-1107-2024, https://doi.org/10.5194/essd-16-1107-2024, 2024
Short summary
Short summary
In this paper, we present the first edition of a global database compiling previously published and unpublished measurements of dissolved organic matter (DOM) collected in coastal waters (CoastDOM v1). Overall, the CoastDOM v1 dataset will be useful to identify global spatial and temporal patterns and to facilitate reuse in studies aimed at better characterizing local biogeochemical processes and identifying a baseline for modelling future changes in coastal waters.
Vao Fenotiana Razanamahandry, Marjolein Dewaele, Gerard Govers, Liesa Brosens, Benjamin Campforts, Liesbet Jacobs, Tantely Razafimbelo, Tovonarivo Rafolisy, and Steven Bouillon
Biogeosciences, 19, 3825–3841, https://doi.org/10.5194/bg-19-3825-2022, https://doi.org/10.5194/bg-19-3825-2022, 2022
Short summary
Short summary
In order to shed light on possible past vegetation shifts in the Central Highlands of Madagascar, we measured stable isotope ratios of organic carbon in soil profiles along both forested and grassland hillslope transects in the Lake Alaotra region. Our results show that the landscape of this region was more forested in the past: soils in the C4-dominated grasslands contained a substantial fraction of C3-derived carbon, increasing with depth.
Rey Harvey Suello, Simon Lucas Hernandez, Steven Bouillon, Jean-Philippe Belliard, Luis Dominguez-Granda, Marijn Van de Broek, Andrea Mishell Rosado Moncayo, John Ramos Veliz, Karem Pollette Ramirez, Gerard Govers, and Stijn Temmerman
Biogeosciences, 19, 1571–1585, https://doi.org/10.5194/bg-19-1571-2022, https://doi.org/10.5194/bg-19-1571-2022, 2022
Short summary
Short summary
This research shows indications that the age of the mangrove forest and its position along a deltaic gradient (upstream–downstream) play a vital role in the amount and sources of carbon stored in the mangrove sediments. Our findings also imply that carbon capture by the mangrove ecosystem itself contributes partly but relatively little to long-term sediment organic carbon storage. This finding is particularly relevant for budgeting the potential of mangrove ecosystems to mitigate climate change.
Man Zhao, Liesbet Jacobs, Steven Bouillon, and Gerard Govers
Biogeosciences, 18, 1511–1523, https://doi.org/10.5194/bg-18-1511-2021, https://doi.org/10.5194/bg-18-1511-2021, 2021
Short summary
Short summary
We investigate the relative importance of two individual factors (hydrodynamical disturbance and aquatic microbial community) that possibly control SOC decomposition rates in river systems. We found aquatic microbial organisms led to rapid SOC decomposition, while effect of mechanical disturbance is relative minor. We propose a simple conceptual model: hydrodynamic disturbance is only important when soil aggregates are strong enough to withstand the disruptive forces imposed by water immersions.
Samuel T. Wilson, Alia N. Al-Haj, Annie Bourbonnais, Claudia Frey, Robinson W. Fulweiler, John D. Kessler, Hannah K. Marchant, Jana Milucka, Nicholas E. Ray, Parvadha Suntharalingam, Brett F. Thornton, Robert C. Upstill-Goddard, Thomas S. Weber, Damian L. Arévalo-Martínez, Hermann W. Bange, Heather M. Benway, Daniele Bianchi, Alberto V. Borges, Bonnie X. Chang, Patrick M. Crill, Daniela A. del Valle, Laura Farías, Samantha B. Joye, Annette Kock, Jabrane Labidi, Cara C. Manning, John W. Pohlman, Gregor Rehder, Katy J. Sparrow, Philippe D. Tortell, Tina Treude, David L. Valentine, Bess B. Ward, Simon Yang, and Leonid N. Yurganov
Biogeosciences, 17, 5809–5828, https://doi.org/10.5194/bg-17-5809-2020, https://doi.org/10.5194/bg-17-5809-2020, 2020
Short summary
Short summary
The oceans are a net source of the major greenhouse gases; however there has been little coordination of oceanic methane and nitrous oxide measurements. The scientific community has recently embarked on a series of capacity-building exercises to improve the interoperability of dissolved methane and nitrous oxide measurements. This paper derives from a workshop which discussed the challenges and opportunities for oceanic methane and nitrous oxide research in the near future.
Cédric Morana, Steven Bouillon, Vimac Nolla-Ardèvol, Fleur A. E. Roland, William Okello, Jean-Pierre Descy, Angela Nankabirwa, Erina Nabafu, Dirk Springael, and Alberto V. Borges
Biogeosciences, 17, 5209–5221, https://doi.org/10.5194/bg-17-5209-2020, https://doi.org/10.5194/bg-17-5209-2020, 2020
Short summary
Short summary
A growing body of studies challenges the paradigm that methane (CH4) production occurs only under anaerobic conditions. Our field experiments revealed that oxic CH4 production is closely related to phytoplankton metabolism and is indeed a common feature in five contrasting African lakes. Nevertheless, we found that methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface.
Jérémy Guilhen, Ahmad Al Bitar, Sabine Sauvage, Marie Parrens, Jean-Michel Martinez, Gwenael Abril, Patricia Moreira-Turcq, and José-Miguel Sánchez-Pérez
Biogeosciences, 17, 4297–4311, https://doi.org/10.5194/bg-17-4297-2020, https://doi.org/10.5194/bg-17-4297-2020, 2020
Short summary
Short summary
The quantity of greenhouse gases (GHGs) released to the atmosphere by human industries and agriculture, such as carbon dioxide (CO2) and nitrous oxide (N2O), has been constantly increasing for the last few decades.
This work develops a methodology which makes consistent both satellite observations and modelling of the Amazon basin to identify and quantify the role of wetlands in GHG emissions. We showed that these areas produce non-negligible emissions and are linked to land use.
Clare Woulds, James B. Bell, Adrian G. Glover, Steven Bouillon, and Louise S. Brown
Biogeosciences, 17, 1–12, https://doi.org/10.5194/bg-17-1-2020, https://doi.org/10.5194/bg-17-1-2020, 2020
Short summary
Short summary
Sedimented hydrothermal vents occur where heated, mineral-rich (hydrothermal) water seeps through seafloor sediments. They host chemosynthetic microbes, which use chemical energy to fix dissolved carbon dioxide into sugars (chemosynthesis). We conducted carbon tracing experiments, and observed chemosynthesis at both vent and non-vent sites. Thus, chemosynthesis occurred over a much larger area than expected, suggesting it is more widespread than previously thought.
Alberto V. Borges, François Darchambeau, Thibault Lambert, Cédric Morana, George H. Allen, Ernest Tambwe, Alfred Toengaho Sembaito, Taylor Mambo, José Nlandu Wabakhangazi, Jean-Pierre Descy, Cristian R. Teodoru, and Steven Bouillon
Biogeosciences, 16, 3801–3834, https://doi.org/10.5194/bg-16-3801-2019, https://doi.org/10.5194/bg-16-3801-2019, 2019
Short summary
Short summary
Tropical rivers might be strong sources of CO2 and CH4 to the atmosphere, although there is an enormous data gap. The origin of CO2 in lowland tropical rivers is not well characterized and can be from terra firme or from wetlands (flooded forests and aquatic macrophytes). We obtained a large field dataset of CO2, CH4 and N2O in the Congo, the second-largest river in the world, which allows us to quantity the emission of these greenhouse gases to the atmosphere and investigate their origin.
Gwenaël Abril and Alberto V. Borges
Biogeosciences, 16, 769–784, https://doi.org/10.5194/bg-16-769-2019, https://doi.org/10.5194/bg-16-769-2019, 2019
Short summary
Short summary
Based on classical concepts in ecology, and a literature survey, we highlight the importance of flooded land as a preferential source of atmospheric carbon to aquatic systems at the global scale. Studies in terrestrial and aquatic ecosystems could be reconciled by considering the occurrence of an efficient wetland CO2 pump to river systems. New methodological approaches coupling hydrology and ecology are also necessary to improve scientific knowledge on carbon fluxes at the land–water interface.
Samuel T. Wilson, Hermann W. Bange, Damian L. Arévalo-Martínez, Jonathan Barnes, Alberto V. Borges, Ian Brown, John L. Bullister, Macarena Burgos, David W. Capelle, Michael Casso, Mercedes de la Paz, Laura Farías, Lindsay Fenwick, Sara Ferrón, Gerardo Garcia, Michael Glockzin, David M. Karl, Annette Kock, Sarah Laperriere, Cliff S. Law, Cara C. Manning, Andrew Marriner, Jukka-Pekka Myllykangas, John W. Pohlman, Andrew P. Rees, Alyson E. Santoro, Philippe D. Tortell, Robert C. Upstill-Goddard, David P. Wisegarver, Gui-Ling Zhang, and Gregor Rehder
Biogeosciences, 15, 5891–5907, https://doi.org/10.5194/bg-15-5891-2018, https://doi.org/10.5194/bg-15-5891-2018, 2018
Short summary
Short summary
To determine the variability between independent measurements of dissolved methane and nitrous oxide, seawater samples were analyzed by multiple laboratories. The results revealed the influences of the different parts of the analytical process, from the initial sample collection to the calculation of the final concentrations. Recommendations are made to improve dissolved methane and nitrous oxide measurements to help preclude future analytical discrepancies between laboratories.
Trent R. Marwick, Fredrick Tamooh, Bernard Ogwoka, Alberto V. Borges, François Darchambeau, and Steven Bouillon
Biogeosciences, 15, 1683–1700, https://doi.org/10.5194/bg-15-1683-2018, https://doi.org/10.5194/bg-15-1683-2018, 2018
Short summary
Short summary
A 2-year biogeochemical record provides annual sediment and element flux estimates for the non-dammed Sabaki River, Kenya, establishing a baseline for future research in light of impending construction of the first major upstream reservoir. Over 80 % of material fluxes occur across the wet season, with annual yields comparable to the adjacent, and dammed, Tana River. Observations at low-flow periods suggest large mammalian herbivores may be vectors of terrestrial subsidies to the water column.
Naomi Geeraert, Fred O. Omengo, Fredrick Tamooh, Trent R. Marwick, Alberto V. Borges, Gerard Govers, and Steven Bouillon
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-31, https://doi.org/10.5194/bg-2017-31, 2017
Manuscript not accepted for further review
Short summary
Short summary
We observed that the relationship between the concentrations and the water discharge in the Tana River changed in wet seasons with and without flooding. Detailed sampling in those seasons is required in order to construct several rating curves and to obtain reliable flux estimates. The sediment and carbon fluxes in function of discharge will help us to asses the flux changes that can be expected when the hydrology changes due to climate change or human impact.
Thibault Lambert, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 5405–5420, https://doi.org/10.5194/bg-13-5405-2016, https://doi.org/10.5194/bg-13-5405-2016, 2016
Short summary
Short summary
This paper aims to investigate the spatial variability in dissolved organic matter (DOM) in terms of both concentration and composition in the Congo River network. Stable carbon isotopes and absorption and fluorescent properties of DOM were used as proxies for DOM composition. This study shows that DOM degradation within the Congo Basin results in the transition from aromatic to aliphatic DOM as well as the role of landscape and water residence time on this transition.
Clare Woulds, Steven Bouillon, Gregory L. Cowie, Emily Drake, Jack J. Middelburg, and Ursula Witte
Biogeosciences, 13, 4343–4357, https://doi.org/10.5194/bg-13-4343-2016, https://doi.org/10.5194/bg-13-4343-2016, 2016
Short summary
Short summary
Estuarine sediments are important locations for carbon cycling and burial. We used tracer experiments to investigate how site conditions affect the way in which seafloor biological communities cycle carbon. We showed that while total respiration rates are primarily determined by temperature, total carbon processing by the biological community is strongly related to
its biomass. Further, we saw a distinct pattern of carbon cycling in sandy sediment, in which uptake by bacteria dominates.
Fleur A. E. Roland, François Darchambeau, Cédric Morana, Sean A. Crowe, Bo Thamdrup, and Alberto V. Borges
Biogeosciences Discuss., https://doi.org/10.5194/bg-2016-300, https://doi.org/10.5194/bg-2016-300, 2016
Manuscript not accepted for further review
Short summary
Short summary
We studied methane consumption in a tropical Great Lake (Lake Kivu, East Africa). Lake Kivu has huge methane concentrations in its deep anoxic waters, but is a very poor emitter of methane to the atmosphere, which suppose a strong methane consumption in the water column. During this study, we put in evidence high aerobic and anaerobic consumption rates, whose relative importance varied with the season (higher aerobic rates in dry season, when the oxic compartment is wider).
Thibault Lambert, Cristian R. Teodoru, Frank C. Nyoni, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 2727–2741, https://doi.org/10.5194/bg-13-2727-2016, https://doi.org/10.5194/bg-13-2727-2016, 2016
Short summary
Short summary
This manuscript presents a detailed analysis of transport and transformation of dissolved organic matter along the Zambezi River and its largest tributary. A particular focus is put on the effects of floodplains/wetlands and reservoirs as well as low-flow vs. high-flow conditions on the longitudinal patterns in DOM concentration and composition. It is the first study to present such a detailed analysis for a whole, large river system, and in particular for a tropical river other than the Amazon.
N. Geeraert, F. O. Omengo, G. Govers, and S. Bouillon
Biogeosciences, 13, 517–525, https://doi.org/10.5194/bg-13-517-2016, https://doi.org/10.5194/bg-13-517-2016, 2016
Short summary
Short summary
Rivers transport a large amount of carbon as dissolved organic carbon (DOC). Our incubation experiments on water of the Tana River, Kenya, showed that microbial decomposition of 10–60 % of the initial DOC occurred within the first 24–48 h. Simultaneously, there was a decrease in isotopic composition, indicating that DOC derived from C4 vegetation is preferentially decomposed. This has implications for the assessment of vegetation in a catchment based on isotope signatures of riverine carbon.
R. L. Sobrinho, M. C. Bernardes, G. Abril, J.-H. Kim, C. I Zell, J.-M. Mortillaro, T. Meziane, P. Moreira-Turcq, and J. S. Sinninghe Damsté
Biogeosciences, 13, 467–482, https://doi.org/10.5194/bg-13-467-2016, https://doi.org/10.5194/bg-13-467-2016, 2016
Short summary
Short summary
The principal objective of the present work is to quantify the fractions of the principal sources of sedimentary organic matter (SOM) in floodplain lakes of the central Amazon basin. The results indicate that the main source of SOM is not the riverine particulate material, as postulated by the literature, but the macrophytes and the forests.
L. C. Cotovicz Jr., B. A. Knoppers, N. Brandini, S. J. Costa Santos, and G. Abril
Biogeosciences, 12, 6125–6146, https://doi.org/10.5194/bg-12-6125-2015, https://doi.org/10.5194/bg-12-6125-2015, 2015
Short summary
Short summary
Air-water CO2 fluxes were monitored in Guanabara Bay (Brazil), a tropical eutrophic coastal embayment. In contrast to other estuaries worldwide, Guanabara Bay behaves as an annual CO2 sink (-9.6 to -18.3 molC m2 yr) due to the concomitant effects of strong radiation, thermal stratification, and high availability of nutrients, which promotes huge phytoplankton development and autotrophy. Our results show that CO2 budget assertions still lack information on tropical marine-dominated estuaries.
C. Morana, F. Darchambeau, F. A. E. Roland, A. V. Borges, F. Muvundja, Z. Kelemen, P. Masilya, J.-P. Descy, and S. Bouillon
Biogeosciences, 12, 4953–4963, https://doi.org/10.5194/bg-12-4953-2015, https://doi.org/10.5194/bg-12-4953-2015, 2015
C. R. Teodoru, F. C. Nyoni, A. V. Borges, F. Darchambeau, I. Nyambe, and S. Bouillon
Biogeosciences, 12, 2431–2453, https://doi.org/10.5194/bg-12-2431-2015, https://doi.org/10.5194/bg-12-2431-2015, 2015
Short summary
Short summary
CO2 and CH4 concentrations and fluxes in the Zambezi River basin are well below the median/average values reported previously for tropical rivers, streams and reservoirs, and mainly controlled by the connectivity with floodplains and the presence of waterfalls and man-made reservoirs. The mass balance suggests that carbon transport to the ocean represents the major component (~60%) of the budget, while emissions to the atmosphere account for less than 40% of the total carbon yield.
C. Morana, A. V. Borges, F. A. E. Roland, F. Darchambeau, J.-P. Descy, and S. Bouillon
Biogeosciences, 12, 2077–2088, https://doi.org/10.5194/bg-12-2077-2015, https://doi.org/10.5194/bg-12-2077-2015, 2015
M. Hagens, C. P. Slomp, F. J. R. Meysman, D. Seitaj, J. Harlay, A. V. Borges, and J. J. Middelburg
Biogeosciences, 12, 1561–1583, https://doi.org/10.5194/bg-12-1561-2015, https://doi.org/10.5194/bg-12-1561-2015, 2015
Short summary
Short summary
This study looks at the combined impacts of hypoxia and acidification, two major environmental stressors affecting coastal systems, in a seasonally stratified basin. Here, the surface water experiences less seasonality in pH than the bottom water despite higher process rates. This is due to a substantial reduction in the acid-base buffering capacity of the bottom water as it turns hypoxic in summer. This highlights the crucial role of the buffering capacity as a modulating factor in pH dynamics.
F. S. Pacheco, M. C. S. Soares, A. T. Assireu, M. P. Curtarelli, F. Roland, G. Abril, J. L. Stech, P. C. Alvalá, and J. P. Ometto
Biogeosciences, 12, 147–162, https://doi.org/10.5194/bg-12-147-2015, https://doi.org/10.5194/bg-12-147-2015, 2015
Short summary
Short summary
CO2 fluxes in Funil Reservoir (FR) is driven by primary production and river inflow dynamics. Our findings suggest that the lack of spatial data in reservoir C budget calculations can affect regional and global estimates. Our results support the idea that the FR is a dynamic system where the hydrodynamics represented by changes in the river inflow and retention time are potentially a more important force driving both the Chl and pCO2 spatial variability than the in-system ecological factors.
G. Abril, S. Bouillon, F. Darchambeau, C. R. Teodoru, T. R. Marwick, F. Tamooh, F. Ochieng Omengo, N. Geeraert, L. Deirmendjian, P. Polsenaere, and A. V. Borges
Biogeosciences, 12, 67–78, https://doi.org/10.5194/bg-12-67-2015, https://doi.org/10.5194/bg-12-67-2015, 2015
Short summary
Short summary
We compared pCO2 data calculated from pH and alkalinity from those measured directly in a large array of temperate and tropical freshwaters. This revealed a large overestimation (up to 300%) of calculated pCO2 in the case of acidic and organic-rich waters, due to a contribution of organic acids anions to alkalinity and a lower buffering capacity of the carbonate system at acidic pH. Given the widespread distribution of acidic freshwaters, direct measurements of water pCO2 are encouraged.
P. Ciais, A. J. Dolman, A. Bombelli, R. Duren, A. Peregon, P. J. Rayner, C. Miller, N. Gobron, G. Kinderman, G. Marland, N. Gruber, F. Chevallier, R. J. Andres, G. Balsamo, L. Bopp, F.-M. Bréon, G. Broquet, R. Dargaville, T. J. Battin, A. Borges, H. Bovensmann, M. Buchwitz, J. Butler, J. G. Canadell, R. B. Cook, R. DeFries, R. Engelen, K. R. Gurney, C. Heinze, M. Heimann, A. Held, M. Henry, B. Law, S. Luyssaert, J. Miller, T. Moriyama, C. Moulin, R. B. Myneni, C. Nussli, M. Obersteiner, D. Ojima, Y. Pan, J.-D. Paris, S. L. Piao, B. Poulter, S. Plummer, S. Quegan, P. Raymond, M. Reichstein, L. Rivier, C. Sabine, D. Schimel, O. Tarasova, R. Valentini, R. Wang, G. van der Werf, D. Wickland, M. Williams, and C. Zehner
Biogeosciences, 11, 3547–3602, https://doi.org/10.5194/bg-11-3547-2014, https://doi.org/10.5194/bg-11-3547-2014, 2014
T. R. Marwick, F. Tamooh, B. Ogwoka, C. Teodoru, A. V. Borges, F. Darchambeau, and S. Bouillon
Biogeosciences, 11, 443–460, https://doi.org/10.5194/bg-11-443-2014, https://doi.org/10.5194/bg-11-443-2014, 2014
F. Tamooh, A. V. Borges, F. J. R. Meysman, K. Van Den Meersche, F. Dehairs, R. Merckx, and S. Bouillon
Biogeosciences, 10, 6911–6928, https://doi.org/10.5194/bg-10-6911-2013, https://doi.org/10.5194/bg-10-6911-2013, 2013
Related subject area
Biogeochemistry: Coastal Ocean
The influence of zooplankton and oxygen on the particulate organic carbon flux in the Benguela Upwelling System
Reviews and syntheses: Biological indicators of low-oxygen stress in marine water-breathing animals
Temperature-enhanced effects of iron on Southern Ocean phytoplankton
Riverine nutrient impact on global ocean nitrogen cycle feedbacks and marine primary production in an Earth system model
The Northeast Greenland Shelf as a potential late-summer CO2 source to the atmosphere
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
High metabolic zinc demand within native Amundsen and Ross Sea phytoplankton communities determined by stable isotope uptake rate measurements
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
Long-term variations of pH in coastal waters along the Korean Peninsula
Responses of microbial metabolic rates to non-equilibrated silicate vs calcium-based ocean alkalinity enhancement
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)
Assessing the impacts of simulated Ocean Alkalinity Enhancement on viability and growth of near-shore species of phytoplankton
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
Countering the effect of ocean acidification in coastal sediments through carbonate mineral additions
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
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
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
Short summary
Short summary
Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Michael R. Roman, Andrew H. Altieri, Denise Breitburg, Erica M. Ferrer, Natalya D. Gallo, Shin-ichi Ito, Karin Limburg, Kenneth Rose, Moriaki Yasuhara, and Lisa A. Levin
Biogeosciences, 21, 4975–5004, https://doi.org/10.5194/bg-21-4975-2024, https://doi.org/10.5194/bg-21-4975-2024, 2024
Short summary
Short summary
Oxygen-depleted ocean waters have increased worldwide. In order to improve our understanding of the impacts of this oxygen loss on marine life it is essential that we develop reliable indicators that track the negative impacts of low oxygen. We review various indicators of low-oxygen stress for marine animals including their use, research needs, and application to confront the challenges of ocean oxygen loss.
Charlotte Eich, Mathijs van Manen, J. Scott P. McCain, Loay J. Jabre, Willem H. van de Poll, Jinyoung Jung, Sven B. E. H. Pont, Hung-An Tian, Indah Ardiningsih, Gert-Jan Reichart, Erin M. Bertrand, Corina P. D. Brussaard, and Rob Middag
Biogeosciences, 21, 4637–4663, https://doi.org/10.5194/bg-21-4637-2024, https://doi.org/10.5194/bg-21-4637-2024, 2024
Short summary
Short summary
Phytoplankton growth in the Southern Ocean (SO) is often limited by low iron (Fe) concentrations. Sea surface warming impacts Fe availability and can affect phytoplankton growth. We used shipboard Fe clean incubations to test how changes in Fe and temperature affect SO phytoplankton. Their abundances usually increased with Fe addition and temperature increase, with Fe being the major factor. These findings imply potential shifts in ecosystem structure, impacting food webs and elemental cycling.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 21, 4469–4493, https://doi.org/10.5194/bg-21-4469-2024, https://doi.org/10.5194/bg-21-4469-2024, 2024
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 increases primary production rates.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Marchiano Holding, and Søren Rysgaard
Biogeosciences, 21, 4037–4050, https://doi.org/10.5194/bg-21-4037-2024, https://doi.org/10.5194/bg-21-4037-2024, 2024
Short summary
Short summary
In this work, we measured the chemistry of seawater from samples obtained from different depths and locations off the east coast of the Northeast Greenland National Park to determine what is influencing concentrations of dissolved CO2. Historically, the region has always been thought to take up CO2 from the atmosphere, but we show that it is possible for the region to become a source in late summer. We discuss the variables that may be related to such changes.
Lennart Thomas Bach, Aaron James Ferderer, Julie LaRoche, and Kai Georg Schulz
Biogeosciences, 21, 3665–3676, https://doi.org/10.5194/bg-21-3665-2024, https://doi.org/10.5194/bg-21-3665-2024, 2024
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.
Riss M. Kell, Rebecca J. Chmiel, Deepa Rao, Dawn M. Moran, Matthew R. McIlvin, Tristan J. Horner, Nicole L. Schanke, Robert B. Dunbar, Giacomo R. DiTullio, and Mak A. Saito
EGUsphere, https://doi.org/10.5194/egusphere-2024-2085, https://doi.org/10.5194/egusphere-2024-2085, 2024
Short summary
Short summary
Southern Ocean phytoplankton play a pivotal role in regulating the uptake and sequestration of carbon dioxide from the atmosphere. This study describes a new stable zinc isotope uptake rate measurement method used to quantify zinc and cadmium uptake rates within native Southern Ocean phytoplankton communities. This data can better inform biogeochemical model predictions of primary production, carbon export, and atmospheric carbon dioxide flux.
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.
Yong-Woo Lee, Mi-Ok Park, Seong-Gil Kim, Tae-Hoon Kim, Yong-Hwa Oh, Sang Heun Lee, and Dong Joo Joung
EGUsphere, https://doi.org/10.5194/egusphere-2024-1836, https://doi.org/10.5194/egusphere-2024-1836, 2024
Short summary
Short summary
A long-term pH variation in coastal waters along the Korean peninsula was assessed for the first time, and it exhibited no significant pH change over an 11-year period. This contrasts with the ongoing pH decline in open oceans and other coastal areas. Analysis of environmental data showed that pH is mainly controlled by dissolved oxygen in bottom waters. This suggests that ocean warming could cause a pH decline in Korean coastal waters, affecting many fish and seaweeds aquaculture operations.
Laura Marin-Samper, Javier Arístegui, Nauzet Hernández-Hernández, and Ulf Riebesell
EGUsphere, https://doi.org/10.5194/egusphere-2024-1776, https://doi.org/10.5194/egusphere-2024-1776, 2024
Short summary
Short summary
This study exposed a natural community to two non-CO2 equilibrated ocean alkalinity enhancement (OAE) deployments using different minerals. Adding alkalinity in this manner decreases dissolved CO2, essential for photosynthesis. While photosynthesis was not suppressed, bloom formation was delayed, potentially impacting marine food webs. The study emphasizes the need for further research on OAE without prior equilibration and its ecological implications
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.
Jessica L. Oberlander, Mackenzie E. Burke, Cat A. London, and Hugh L. MacIntyre
EGUsphere, https://doi.org/10.5194/egusphere-2024-971, https://doi.org/10.5194/egusphere-2024-971, 2024
Short summary
Short summary
OAE is a promising negative emission technology that could restore the oceanic pH and carbonate system to a pre-industrial state. To our knowledge, this paper is the first to assess the potential impact of OAE on phytoplankton through an analysis of prior studies and the effects of simulated OAE on photosynthetic competence. Our findings suggest that there may be little if any significant impact on most phytoplankton studied to date if OAE is conducted in well-flushed, near-shore environments.
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.
Kadir Bice, Tristen Myers, George Waldbusser, and Christof Meile
EGUsphere, https://doi.org/10.5194/egusphere-2024-796, https://doi.org/10.5194/egusphere-2024-796, 2024
Short summary
Short summary
We studied the effect of addition of carbonate minerals on coastal sediments, We carried out laboratory experiments to quantify the dissolution kinetics and integrated these observations into a numerical model that describes biogeochemical cycling in surficial sediments. Using the model, we demonstrate the buffering effect of the mineral additions and its duration. We quantify the effect under different environmental conditions and assess the potential for increased atmospheric CO2 uptake.
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.
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.
Cited articles
Abril, G. and Borges, A. V.: Carbon dioxide and methane emissions from
estuaries, in: Greenhouse Gases Emissions from Natural Environments and
Hydroelectric Reservoirs: Fluxes and Processes. Environmental Science Series,
edited by: Tremblay, A., Varfalvy, L., Roehm, C., and Garneau, M.,
Springer-Verlag Berlin, New York, 187–207, 2004.
Abril, G., Etcheber, H., Borges, A. V., and Frankignoulle, M.: Excess
atmospheric carbon dioxide transported by rivers into the Scheldt estuary, C.
R. Seances Acad. Sci. III, 330, 761–768, https://doi.org/10.1016/S1251-8050(00)00231-7,
2000.
Abril, G., Nogueira, M., Etcheber, H., Cabecadas, G., Lemaire, E., and
Brogueira, M. J.: Behaviour of organic carbon in nine contrasting European
estuaries, Estuar. Coast. Shelf S., 54, 241–262, https://doi.org/10.1006/ecss.2001.0844,
2002.
Abril, G., Bouillon, S., Darchambeau, F., Teodoru, C. R., Marwick, T. R.,
Tamooh, F., Ochieng Omengo, F., Geeraert, N., Deirmendjian, L., Polsenaere,
P., and Borges, A. V.: Technical Note: Large overestimation of pCO2
calculated from pH and alkalinity in acidic, organic-rich freshwaters,
Biogeosciences, 12, 67–78, https://doi.org/10.5194/bg-12-67-2015, 2015.
Adamson, P. T., Rutherfurd, I. D., Peel, M. C., and Conlan, I. A.: The
Hydrology of the Mekong River, in: The Mekong, edited by: Ian, C. C.,
Academic Press, San Diego, 53–76, 2009.
Alin, S. R., Rasera, M. F. F. L., Salimon, C. I., Richey, J. E., Holtgrieve,
G. W., and Krusche, A. V., and Snidvongs, A.: Physical controls on carbon
dioxide transfer velocity and flux in low-gradient river systems and
implications for regional carbon budgets, J. Geophys. Res., 116, G01009,
https://doi.org/10.1029/2010JG001398, 2011.
Alongi, D. M., Dixon, P., Johnston, D. J., Tien, D. V., and Xuan, T. T.:
Pelagic processes in extensive shrimp ponds of the Mekong delta, Vietnam,
Aquaculture, 175, 121–141, https://doi.org/10.1016/S0044-8486(99)00078-2, 1999a.
Alongi, D. M., Tirendi, F., and Trott, L. A.: Rates and pathways of benthic
mineralization in extensive shrimp ponds of the Mekong delta, Vietnam,
Aquaculture, 175, 269–292, https://doi.org/10.1016/S0044-8486(99)00077-0, 1999b.
Alongi, D. M., Johnston, D. J., and Xuan, T. T.: Carbon and nitrogen budgets
in shrimp ponds of extensive mixed shrimp-mangrove forestry farms in the
Mekong delta, Vietnam, Aquacult. Res., 31, 387–399,
https://doi.org/10.1046/j.1365-2109.2000.00457.x, 2000.
Amiotte Suchet, P., Probst, J., and Ludwig, W.: Worldwide distribution of
continental rock lithology: Implications for the atmospheric/soil CO2
uptake by continental weathering and alkalinity river transport to the
oceans, Global Biogeochem. Cy., 17, 1038, https://doi.org/10.1029/2002GB001891, 2003.
Anthony, E. J., Brunier, G., Besset, M., Goichot, M., Dussouillez, P., and
Nguyen, V. L.: Linking rapid erosion of the Mekong River delta to human
activities, Sci. Rep., 5, 14745, https://doi.org/10.1038/srep14745, 2015.
Bange, H. W., Bartell, U. H., Rapsomanikis, S., and Andrea, M. O.: Methane in
the Baltic and North Seas and a reassessment of the marine emissions of
methane, Global Biogeochem. Cy., 8, 465–480, https://doi.org/10.1029/94GB02181, 1994.
Bastviken, D., Tranvik, L. J., Downing, J. A., Crill, P. M., and
Enrich-Prast, A.: Freshwater methane emissions offset the continental carbon
sink, Science, 331, 50 pp., https://doi.org/10.1126/science.1196808, 2011.
Bates, T. S., Kelly, K. C., Johnson, J. E., and Gammon, R. H.: A reevaluation
of the open ocean source of methane to the atmosphere, J. Geophys. Res., 101,
6953–6961, https://doi.org/10.1029/95JD03348, 1996.
Bianchi, T. S.: Biogeochemistry of Estuaries, Oxford University Press,
720 pp., 2006.
Borges, A. V.: Do we have enough pieces of the jigsaw to integrate CO2
fluxes in the coastal ocean?, Estuaries, 28, 3–27, https://doi.org/10.1007/bf02732750,
2005.
Borges, A. V. and Abril, G.: Carbon dioxide and methane dynamics in
estuaries, in: Treatise on Estuarine and Coastal Science, edited by:
Wolanski, E. and McLusky, D., Academic Press, Waltham, 119–161, 2011.
Borges, A. V., Djenidi, S., Lacroix, G., Théate, J., Delille, B., and
Frankignoulle, M.: Atmospheric CO2 flux from mangrove surrounding
waters, Geophys. Res. Lett., 30, 1558, https://doi.org/10.1029/2003GL017143, 2003.
Borges, A. V., Delille, B., Schiettecatte, L.-S., Gazeau, F., Abril, G., and
Frankignoulle, M.: Gas transfer velocities of CO2 in three European
estuaries (Randers Fjord, Scheldt and Thames), Limnol. Oceanogr., 49,
1630–1641, https://doi.org/10.4319/lo.2004.49.5.1630, 2004.
Borges, A. V., Delille, B., and Frankignoulle, M.: Budgeting sinks and
sources of CO2 in the coastal ocean: Diversity of ecosystems counts,
Geophys. Res. Lett., 32, L14601, https://doi.org/10.1029/2005gl023053, 2005.
Borges, A. V., Schiettecatte, L.-S., Abril, G., Delille, B., and Gazeau, E.:
Carbon dioxide in European coastal waters, Estuar. Coast. Shelf S., 70,
375–387, https://doi.org/10.1016/j.ecss.2006.05.046, 2006.
Borges, A. V., Darchambeau, F., Teodoru, C. R., Marwick, T. R., Tamooh, F.,
Geeraert, N., Omengo, F. O., Guérin, F., Lambert, T., Morana, C., Okuku,
E., and Bouillon, S.: Globally significant greenhouse gas emissions from
African inland waters, Nat. Geosci., 8, 637–642, https://doi.org/10.1038/NGEO2486,
2015a.
Borges, A. V., Abril, G., Darchambeau, F., Teodoru, C. R., Deborde, J.,
Vidal, L. O., Lambert, T., and Bouillon, S.: Divergent biophysical controls
of aquatic CO2 and CH4 in the World's two largest rivers, Sci. Rep., 5,
15614, https://doi.org/10.1038/srep15614, 2015b.
Borges, A. V., Champenois, W., Gypens, N., Delille, B., and Harlay, J.:
Massive marine methane emissions from near-shore shallow coastal areas, Sci.
Rep., 6, 27908, https://doi.org/10.1038/srep27908, 2016.
Borges, A. V., Speeckaert, G., Champenois, W., Scranton, M. I., and Gypens,
N.: Productivity and temperature as drivers of seasonal and spatial
variations of dissolved methane in the Southern Bight of the North Sea,
Ecosystems, 1–17, https://doi.org/10.1007/s10021-017-0171-7, 2017.
Bouillon, S., Korntheuer, M., Baeyens, W., and Dehairs, F.: A new automated
setup for stable isotope analysis of dissolved organic carbon, Limnol.
Oceanogr.-Meth., 4, 216–226, https://doi.org/10.4319/lom.2006.4.216, 2006.
Bouillon, S., Dehairs, F., Schiettecatte, L.-S., and Borges, A. V.:
Biogeochemistry of the Tana estuary and delta (northern Kenya), Limnol.
Oceanogr., 52, 46–59, https://doi.org/10.4319/lo.2007.52.1.0046, 2007a.
Bouillon, S., Dehairs, F., Velimirov, B., Abril, G., and Borges, A. V.:
Dynamics of organic and inorganic carbon across contiguous mangrove and
seagrass systems (Gazi Bay, Kenya), J. Geophys. Res., 112, G02018,
https://doi.org/10.1029/2006jg000325, 2007b.
Bouillon, S., Gillikin, D. P., and Connolly, R. M.: Use of stable isotopes to
understand food webs and ecosystem functioning in estuaries, in: Treatise on
Estuarine and Coastal Science, edited by: Wolanski, E. and McLusky, D. S., 7,
143–173, Waltham: Academic Press, 2012a.
Bouillon, S., Yambélé, A., Spencer, R. G. M., Gillikin, D. P.,
Hernes, P. J., Six, J., Merckx, R., and Borges, A. V.: Organic matter
sources, fluxes and greenhouse gas exchange in the Oubangui River (Congo
River basin), Biogeosciences, 9, 2045–2062,
https://doi.org/10.5194/bg-9-2045-2012, 2012b.
Bouillon, S., Yambélé, A., Gillikin, D. P., Teodoru, C., Darchambeau,
F., Lambert, T., and Borges, A. V.: Contrasting biogeochemical
characteristics of right-bank tributaries and a comparison with the mainstem
Oubangui River, Central African Republic (Congo River basin), Sci. Rep., 4,
5402, https://doi.org/10.1038/srep05402, 2014.
Brewer, P. G. and Goldman, J. C.: Alkalinity changes generated by
phytoplankton growth, Limnol. Oceanogr., 21, 108–117,
https://doi.org/10.4319/lo.1976.21.1.0108, 1976.
Cai, W.-J.: Estuarine and coastal ocean carbon paradox: CO2 sinks or sites
of terrestrial carbon incineration?, Annu. Rev. Mar. Sci., 3, 123–145,
https://doi.org/10.1146/annurev-marine-120709-142723, 2011.
Cai, W.-J. and Wang, Y.: The chemistry, fluxes, and sources of carbon dioxide
in the estuarine waters of the Satilla and Altamaha Rivers, Georgia, Limnol.
Oceanogr., 43, 657–668, https://doi.org/10.4319/lo.1998.43.4.0657, 1998.
Cai, W.-J., Guo, X., Chen, C.-T. A., Dai, M., Zhang, L., Zhai, W., Lohrenz,
S. E., Yin, K., Harrison, P. J., and Wang, Y.: A comparative overview of
weathering intensity and HCO
Call, M., Maher, D. T., Santos, I. R., Ruiz-Halpern, S., Mangion, P.,
Sanders, C. J., Erler, D. V., Oakes, J. M., Rosentreter, J., Murray, R., and
Eyre, B. D.: Spatial and temporal variability of carbon dioxide and methane
fluxes over semi-diurnal and spring–neap–spring timescales in a mangrove
creek, Geochim. Cosmochim. Ac., 150, 211–225, https://doi.org/10.1016/j.gca.2014.11.023,
2015.
Cardozo, A. P. and Odebrecht, C.: Effects of shrimp pond water on
phytoplankton: importance of salinity and trophic status of the receiving
environment, Aquacult. Res., 45, 1600–1610, https://doi.org/10.1111/are.12106, 2014.
Chen, C.-T. A. and Borges, A. V.: Reconciling opposing views on carbon
cycling in the coastal ocean: Continental shelves as sinks and near-shore
ecosystems as sources of atmospheric CO2, Deep-Sea Res., 56, 578–590,
https://doi.org/10.1016/j.dsr2.2009.01.001, 2009.
Chen, C.-T. A., Huang, T. H., Fu, Y. H., Bai, Y., and He, X.: Strong sources
of CO2 in upper estuaries become sinks of CO2 in large river
plumes, Curr. Opin. Env. Sust., 4, 179–185,
https://doi.org/10.1016/j.cosust.2012.02.003, 2012.
Chen, C.-T. A., Huang, T.-H., Chen, Y.-C., Bai, Y., He, X., and Kang, Y.:
Air–sea exchanges of CO2 in the world's coastal seas, Biogeosciences, 10,
6509–6544, https://doi.org/10.5194/bg-10-6509-2013, 2013.
Cotovicz Jr., L. C., Knoppers, B. A., Brandini, N., Costa Santos, S. J., and
Abril, G.: A strong CO2 sink enhanced by eutrophication in a tropical
coastal embayment (Guanabara Bay, Rio de Janeiro, Brazil), Biogeosciences,
12, 6125–6146, https://doi.org/10.5194/bg-12-6125-2015, 2015.
Crosswell, J. R., Wetz, M. S., Hales, B., and Paerl, H. W.: Air-water
CO2 fluxes in the microtidal Neuse River Estuary, North Carolina, J.
Geophys. Res., 117, C08017, https://doi.org/10.1029/2012JC007925, 2012.
Dai, A. and Trenberth, K. E.: Estimates of freshwater discharge from
continents: latitudinal and seasonal variations, J. Hydrometeorol., 3,
660–687, https://doi.org/10.1175/1525-7541(2002)003<0660:EOFDFC>2.0.CO;2, 2002.
Darby, S. E., Hackney, C. R., Leyland, J., Kummu, M., Lauri, H., Parsons, D.
R., Best, J. L., Nicholas, A. P., and Aalto, R.: Fluvial sediment supply to a
mega-delta reduced by shifting tropical-cyclone activity, Nature, 539,
276–279, https://doi.org/10.1038/nature19809, 2016.
de Graaf, G. J. and Xuan, T. T.: Extensive shrimp farming, mangrove clearance
and marine fisheries in the southern provinces of Vietnam, Mangroves Salt
Marshes, 2, 159–166, https://doi.org/10.1023/A:1009975210487, 1998.
Descy, J.-P., Darchambeau, F., Lambert, T., Stoyneva, M. P., Bouillon, S.,
Borges, A. V.: Phytoplankton dynamics in the Congo River, Freshwater Biol.,
62, 87–101, https://doi.org/10.1111/fwb.12851, 2017.
Dürr, H. H., Laruelle, G. G., van Kempen, C. M., Slomp, C. P., Meybeck,
M., and Middelkoop, H.: Worldwide typology of nearshore coastal systems:
Defining the estuarine filter of river inputs to the oceans, Estuar. Coast.,
34, 441–458, https://doi.org/10.1007/s12237-011-9381-y, 2011.
Ellis, E. E., Keil, R. G., Ingalls, A. E., Richey, J. E., and Alin, S. R.:
Seasonal variability in the sources of particulate organic matter of the
Mekong River as discerned by elemental and lignin analyses, J. Geophys. Res.,
117, G01038, https://doi.org/10.1029/2011JG001816, 2012.
Frankignoulle, M. and Borges, A. V.: Direct and indirect pCO2
measurements in a wide range of pCO2 and salinity values (the Scheldt
estuary), Aquat. Geochem., 7, 267–273, https://doi.org/10.1023/A:1015251010481, 2001.
Frankignoulle, M., Bourge, I., and Wollast, R.: Atmospheric CO2 fluxes
in a highly polluted estuary (The Scheldt), Limnol. Oceanogr., 41, 365–369,
https://doi.org/10.4319/lo.1996.41.2.0365, 1996.
Frankignoulle, M., Abril, G., Borges, A., Bourge, I., Canon, C., Delille, B.,
Libert, E., and Théate, J.-M.: Carbon dioxide emission from European
estuaries, Science, 282, 434–436, https://doi.org/10.1126/science.282.5388.434, 1998.
Froelich, P. N., Klinkhammer, G. P., Bender, M. L., Luedtke, N. A., Heath, G.
R., Cullen, D., Dauphin, P., Hammond, D., Hartman, B., and Maynard, V.: Early
oxidation of organic matter in pelagic sediments of the eastern equatorial
Atlantic: suboxic diagenesis, Geochim. Cosmochim. Ac., 43, 1075–1090,
https://doi.org/10.1016/0016-7037(79)90095-4, 1979.
Fu, K. D., He, D. M., and Lu, X. X.: Sedimentation in the Manwan reservoir in
the Upper Mekong and its downstream impacts, Quaternary Int., 186, 91–99,
https://doi.org/10.1016/j.quaint.2007.09.041, 2008.
Gaillardet, J., Dupré, B., Louvat, P., and Allègre, C. J.: Global
silicate weathering and CO2 consumption rates deduced from the chemistry
of large rivers, Chem. Geol., 159, 3–30, https://doi.org/10.1016/S0009-2541(99)00031-5,
1999.
Gao, S., Wang, H., Liu, G., and Li, H.: Spatio-temporal variability of
chlorophyll a and its responses to sea surface temperature, winds and height
anomaly in the western South China Sea, Acta Oceanol. Sin., 32, 48–58,
https://doi.org/10.1007/s13131-013-0266-8, 2013.
Gattuso, J.-P., Frankignoulle, M., and Wollast, R.: Carbon and carbonate
metabolism in coastal aquatic ecosystems, Annu. Rev. Ecol. Evol., 29,
405–433, https://doi.org/10.1146/annurev.ecolsys.29.1.405, 1998.
Grosse, J., Bombar, D., Doan, H. N., Nguyen, L. N., and Voss, M.: The Mekong
River plume fuels nitrogen fixation and determines phytoplankton species
distribution in the South China Sea during low- and high-discharge season,
Limnol. Oceanogr., 55, 1668–1680, https://doi.org/10.4319/lo.2010.55.4.1668, 2010.
Guo, X., Dai, M., Zhai, W., Cai, W.-J., and Chen, B.: CO2 flux and
seasonal variability in a large subtropical estuarine system, the Pearl River
Estuary, China, J. Geophys. Res., 114, G03013, https://doi.org/10.1029/2008JG000905,
2009.
Hellings, L., Dehairs, F., Tackx, M., Keppens, E., and Baeyens, W.: Origin
and fate of organic carbon in the freshwater part of the Scheldt Estuary as
traced by stable carbon isotope composition, Biogeochemistry, 47, 167–186,
https://doi.org/10.1007/BF00994921, 1999.
Henry, W.: Experiments on the quantity of gases absorbed by water, at
different temperatures, and under different pressures, Philos. T. R. Soc.
Lond., 93, 29–274, https://doi.org/10.1098/rstl.1803.0004, 1803.
Huang, T. H., Chen, C. T. A., Tseng, H. C., Lou, J. Y., Wang, S. L., Yang,
L., Kandasamy, S., Gao, X., Wang, J. T., Aldrian, E., Jacinto, G. S.,
Anshari, G. Z., Sompongchaiyakul, P., and Wang, B. J.: Riverine carbon fluxes
to the South China Sea, J. Geophys. Res.-Biogeo., 122, 1239–1259,
https://doi.org/10.1002/2016JG003701, 2017.
Huang, W.-J., Cai, W.-J., Wang, Y., Lohrenz, S. E., and Murrell, M. C.: The
carbon dioxide system on the Mississippi River-dominated continental shelf in
the northern Gulf of Mexico: 1. Distribution and air-sea CO2 flux, J.
Geophys. Res., 120, 1429–1445, https://doi.org/10.1002/2014JC010498, 2015.
IPCC: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A:
Global and Sectoral Aspects. Contribution of Working Group II to the Fifth
Assessment Report of the Intergovernmental Panel on Climate Change, edited
by: Field, C. B., Barros, V. R., Dokken, D. J., Mach, K. J., Mastrandrea, M.
D., Bilir, T. E., Chatterjee, M., Ebi, K. L., Estrada, Y. O., Genova, R. C.,
Girma, B., Kissel, E. S., Levy, A. N., MacCracken, S., Mastrandrea, P. R.,
and White, L. L., Cambridge University Press, Cambridge, 1132 pp., 2014.
Joesoef, A., Huang, W.-J., Gao, Y., and Cai, W.-J.: Air–water fluxes and
sources of carbon dioxide in the Delaware Estuary: spatial and seasonal
variability, Biogeosciences, 12, 6085–6101,
https://doi.org/10.5194/bg-12-6085-2015, 2015.
Joesoef, A., Kirchman, D. L., Sommerfield, C. K., and Cai, W.-J.: Seasonal
variability of the inorganic carbon system in a large coastal plain estuary,
Biogeosciences, 14, 4949–4963, https://doi.org/10.5194/bg-14-4949-2017,
2017.
Kirschke, S., Bousquet, P., Ciais, P., Saunois, M., Canadell, J. G.,
Dlugokencky, E. J., Bergamaschi, P., Bergmann, D., Blake, D. R., Bruhwiler,
L., Cameron-Smith, P., Castaldi, S., Chevallier, F., Feng, L., Fraser, A.,
Heimann, M., Hodson, E. L., Houweling, S., Josse, B., Fraser, P. J., Krummel,
P. B., Lamarque, J.-F., Langenfelds, R. L., Le Quéré, C., Naik, V.,
O'Doherty, S., Palmer, P. I., Pison, I., Plummer, D., Poulter, B., Prinn, R.
G., Rigby, M., Ringeval, B., Santini, M., Schmidt, M., Shindell, D. T.,
Simpson, I. J., Spahni, R., Steele, L. P., Strode, S. A., Sudo, K., Szopa,
S., van der Werf, G. R., Voulgarakis, A., van Weele, M., Weiss, R. F.,
Williams, J. E., and Zeng, G.: Three decades of global methane sources and
sinks, Nat. Geosci., 6, 813–823, https://doi.org/10.1038/ngeo1955, 2013.
Kondolf, G. M., Rubin, Z. K., and Minear, J. T.: Dams on the Mekong:
Cumulative sediment starvation, Water Resour. Res., 50, 5158–5169,
https://doi.org/10.1002/2013WR014651, 2014.
Koné, Y. J.-M. and Borges, A. V.: Dissolved inorganic carbon dynamics in
the waters surrounding forested mangroves of the Ca Mau Province (Vietnam),
Estuar. Coast. Shelf S., 77, 409–421, https://doi.org/10.1016/j.ecss.2007.10.001, 2008.
Koné, Y. J. M., Abril, G., Kouadio, K. N., Delille, B., and Borges, A.
V.: Seasonal variability of carbon dioxide in the rivers and lagoons of Ivory
Coast (West Africa), Estuar. Coast., 32, 246–260,
https://doi.org/10.1007/s12237-008-9121-0, 2009.
Koné, Y. J. M., Abril, G., Delille, B., and Borges, A. V.: Seasonal
variability of methane in the rivers and lagoons of Ivory Coast (West
Africa), Biogeochemistry, 100, 21–37, https://doi.org/10.1007/s10533-009-9402-0,
2010.
Koroleff, F.: Determinationo of silicon, in: Methods of seawater analysis,
edited by: Grasshoff, K., Ehrhardt, M., and Kremling, K., Verlag Chemie,
Weinheim/Deerfield Beach, 174–187, 1983.
Kummu, M., Lu, X. X., Wang, J. J., and Varis, O.: Basinwide sediment trapping
efficiency of emerging reservoirs along the Mekong, Geomorphology, 119,
181–197, https://doi.org/10.1016/J.Geomorph.2010.03.018, 2010.
Lauri, H., de Moel, H., Ward, P. J., Räsänen, T. A., Keskinen, M.,
and Kummu, M.: Future changes in Mekong River hydrology: impact of climate
change and reservoir operation on discharge, Hydrol. Earth Syst. Sci., 16,
4603–4619, https://doi.org/10.5194/hess-16-4603-2012, 2012.
Laruelle, G. G., Dürr, H. H., Slomp, C. P., and Borges, A. V.: Evaluation
of sinks and sources of CO2 in the global coastal ocean using a
spatially-explicit typology of estuaries and continental shelves, Geophys.
Res. Lett., 37, L15607, https://doi.org/10.1029/2010gl043691, 2010.
Laruelle, G. G., Dürr, H. H., Lauerwald, R., Hartmann, J., Slomp, C. P.,
Goossens, N., and Regnier, P. A. G.: Global multi-scale segmentation of
continental and coastal waters from the watersheds to the continental
margins, Hydrol. Earth Syst. Sci., 17, 2029–2051,
https://doi.org/10.5194/hess-17-2029-2013, 2013.
Le, T. P. Q., Marchand, C., Ho, C. T., Duong, T. T., Nguyen, H. T. M., XiXi,
L., Vu, D. A., Doan, P. K., and Le, N. D.: CO2 partial pressure and CO2
emissions from the lower Red River (Vietnam), Biogeosciences Discuss.,
https://doi.org/10.5194/bg-2017-505, in review, 2017.
Lefèvre, N., Flores Montes, M., Gaspar, F. L., Rocha, C., Jiang, S., De
Araújo, M. C., and Ibánhez, J. S. P.: Net Heterotrophy in the Amazon
Continental Shelf Changes Rapidly to a Sink of CO2 in the Outer Amazon
Plume, Front. Mar. Sci., 4, 278, https://doi.org/10.3389/fmars.2017.00278, 2017.
Le Quéré, C., Andrew, R. M., Canadell, J. G., Sitch, S., Korsbakken,
J. I., Peters, G. P., Manning, A. C., Boden, T. A., Tans, P. P., Houghton, R.
A., Keeling, R. F., Alin, S., Andrews, O. D., Anthoni, P., Barbero, L., Bopp,
L., Chevallier, F., Chini, L. P., Ciais, P., Currie, K., Delire, C., Doney,
S. C., Friedlingstein, P., Gkritzalis, T., Harris, I., Hauck, J., Haverd, V.,
Hoppema, M., Klein Goldewijk, K., Jain, A. K., Kato, E., Körtzinger, A.,
Landschützer, P., Lefèvre, N., Lenton, A., Lienert, S., Lombardozzi,
D., Melton, J. R., Metzl, N., Millero, F., Monteiro, P. M. S., Munro, D. R.,
Nabel, J. E. M. S., Nakaoka, S.-I., O'Brien, K., Olsen, A., Omar, A. M., Ono,
T., Pierrot, D., Poulter, B., Rödenbeck, C., Salisbury, J., Schuster, U.,
Schwinger, J., Séférian, R., Skjelvan, I., Stocker, B. D., Sutton, A.
J., Takahashi, T., Tian, H., Tilbrook, B., van der Laan-Luijkx, I. T., van
der Werf, G. R., Viovy, N., Walker, A. P., Wiltshire, A. J., and Zaehle, S.:
Global Carbon Budget 2016, Earth Syst. Sci. Data, 8, 605–649,
https://doi.org/10.5194/essd-8-605-2016, 2016.
Li, S. and Bush, R. T.: Changing fluxes of carbon and other solutes from the
Mekong River, Sci. Rep., 5, 16005, https://doi.org/10.1038/srep16005, 2015.
Li, S. Y., Lu, X. X., and Bush, R. T.: CO2 partial pressure and CO2
emission in the Lower Mekong River, J. Hydrol., 504, 40–56,
https://doi.org/10.1016/j.jhydrol.2013.09.024, 2013.
Li, S. Y., Lu, X. X., and Bush, R. T.: Chemical weathering and CO2
consumption in the Lower Mekong River, Sci. Total Environ., 472, 162–177,
https://doi.org/10.1016/j.scitotenv.2013.11.027, 2014.
Liu, J. P., DeMaster, D. J., Nguyen, T. T., Saito, Y., Nguyen, V. L., Ta, T.
K. O., and Li, X.: Stratigraphic formation of the Mekong River Delta and its
recent shoreline changes, Oceanography 30, 72–83,
https://doi.org/10.5670/oceanog.2017.316, 2017.
Liu, K.-K., Chao, S.-Y., Shaw, P.-T., Gong, G.-C., Chen, C.-C., and Tang, T.
Y.: Monsoon-forced chlorophyll distribution and primary production in the
South China Sea: observations and a numerical study, Deep-Sea Res. Pt. I, 49,
1387–1412, https://doi.org/10.1016/S0967-0637(02)00035-3, 2002.
Liu, Z. H., Wolfgang, D., and Wang, H. J.: A new direction in effective
accounting for the atmospheric CO2 budget: considering the combined
action of carbonate dissolution, the global water cycle and photosynthetic
uptake of DIC by aquatic organisms. Earth Sci. Rev. 99, 162-172,
https://doi.org/10.1016/j.earscirev.2010.03.001, 2010.
Loisel, H., Vantrepotte, V., Ouillon, S., Ngoc, D. D., Herrmann, M., Tran,
V., Mériaux, X., Dessailly, D., Jamet, C., Duhaut, T., Nguyen, H. H., and
Nguyen, T. V.: Assessment and analysis of the chlorophyll-a concentration
variability over the Vietnamese coastal waters from the MERIS ocean color
sensor (2002–2012), Remote Sens. Environ., 190, 217–232,
https://doi.org/10.1016/j.rse.2016.12.016, 2017.
Lu, X. X., Li, S., Kummu, M., Padawangi, R., and Wang, J. J.: Observed
changes in the water flow at Chiang Saen in the lower Mekong: Impacts of
Chinese dams?, Quaternary Int., 336, 145–157,
https://doi.org/10.1016/j.quaint.2014.02.006, 2014.
Ludwig, W., Probst, J. L., and Kempe, S.: Predicting the oceanic input of
organic carbon by continental erosion, Global Biogeochem. Cy., 10, 23–41,
https://doi.org/10.1029/95GB02925, 1996.
Manaka, T., Otani, S., Inamura, A., Suzuki, A., Aung, T., Roachanakanan, R.,
Ishiwa, T., and Kawahata, H.: Chemical weathering and long-term CO2
consumption in the Ayeyarwady and Mekong river basins in the Himalayas, J.
Geophys. Res.-Biogeo., 120, 1165–1175, https://doi.org/10.1002/2015JG002932, 2015.
Martin, E. E., Ingalls, A. E., Richey, J. E., Keil, R. G., Santos, G. M.,
Truxal, L. T., Alin, S. R., and Druffel, E. R. M.: Age of riverine carbon
suggests rapid export of terrestrial primary production in tropics, Geophys.
Res. Lett., 40, 5687–5691, https://doi.org/10.1002/2013GL057450, 2013.
Meybeck, M.: Carbon, nitrogen, and phosphorus transport by world rivers, Am.
J. Sci., 282, 401–450, https://doi.org/10.2475/ajs.282.4.401, 1982.
Meybeck, M. and Carbonnel, J. P.: Chemical transport by the Mekong river,
Nature, 255, 134–136, https://doi.org/10.1038/255134a0, 1975.
Middelburg, J. J., Nieuwenhuize, J., Iversen, N., Høgh, N., De Wilde, H.,
Helder, W., Seifert, R., and Christof, O.: Methane distribution in European
tidal estuaries, Biogeochemistry, 59, 95–119, https://doi.org/10.1023/A:1015515130419,
2002.
Milliman, J. D. and Farnsworth, K. L.: River Discharge to the Coastal Ocean:
A Global Synthesis Cambridge University Press, 392 pp., 2011.
Mook, W. G. and Tan, T. C.: Stable carbon isotopes in rivers and estuaries,
in: Biogeochemistry of major world rivers, edited by: Degens, E. T., Kempe,
S., and Richey, J. E., SCOPE, Wiley, 245–264, 1991.
Morris, A. W., Mantoura, R. F. C., Bale, A. J., and Howland, R. J. M.: Very
low salinity regions of estuaries: important sites for chemical and
biological reactions, Nature, 274, 678–680, https://doi.org/10.1038/274678a0, 1978.
Muylaert, K. and Sabbe, K.: Spring phytoplankton assemblages in and around
the maximum turbidity zone of the estuaries of the Elbe (Germany), the
Schelde (Belgium/The Netherlands) and the Gironde (France), J. Mar. Syst.,
22, 133–149, https://doi.org/10.1016/S0924-7963(99)00037-8, 1999.
Nguyen, A. D., Savenije, H. H. G., Pham, D. N., and Tang, D. T.: Using salt
intrusion measurements to determine the freshwater discharge distribution
over the branches of a multi-channel estuary: The Mekong Delta case, Estuar.
Coast. Shelf S., 77, 433–445, https://doi.org/10.1016/j.ecss.2007.10.010, 2008.
Nguyen, L.-D., Pham-Bach, V., Nguyen-Thanh, M., Pham-Thi, M.-T., and
Hoang-Phi, P.: Change detection of land use and riverbank in Mekong Delta,
Vietnam using time series remotely sensed data, J. Res. Ecol., 2, 370–374,
https://doi.org/10.3969/j.issn.1674-764x.2011.04.011, 2011.
Piman, T., Lennaerts, T., and Southalack, P.: Assessment of hydrological
changes in the lower Mekong Basin from basin-wide development scenarios,
Hydrol. Process., 27, 2115–2125, https://doi.org/10.1002/hyp.9764, 2013.
Piman, T., Cochrane, T. A., and Arias, M. E.: Effect of proposed large dams
on water flows and hydropower production in the Sekong, Sesan and Srepok
rivers of the Mekong basin, River Res. Appl., 32, 2095–2108,
https://doi.org/10.1002/rra.3045, 2016.
Qiu, F., Fang, W., and Fanf, G.: Seasonal-to-interannual variability of
chlorophyll in centralwestern South China Sea extracted from SeaWiFS, Chin.
J. Oceanol. Limn., 29, 18–25, https://doi.org/10.1007/s00343-011-9931-y, 2011.
Ragueneau, O., Lancelot, C., Egorov, V., Vervlimmeren, J., Cociasu, A.,
Déliat, G., Krastev, A., Daoud, N., Rousseau, V., Popovitchev, V., Brion,
N., Popa, L., and Cauwet, G.: Biogeochemical transformations of inorganic
nutrients in the mixing zone between the Danube River and the North-western
Black Sea, Estuar. Coast. Shelf S., 54, 321–336, https://doi.org/10.1006/ecss.2000.0650,
2002.
Rao, G. D. and Sarma, V. V. S. S.: Variability in concentrations and fluxes
of methane in the Indian estuaries, Estuar. Coast., 39, 1639–1650,
https://doi.org/10.1007/s12237-016-0112-2, 2016.
Raymond, P. A. and Cole, J. J.: Gas exchange in rivers and estuaries:
Choosing a gas transfer velocity, Estuaries, 24, 312–317,
https://doi.org/10.2307/1352954, 2001.
Raymond, P. A., Hartmann, J., Lauerwald, R., Sobek, S., McDonald, C., Hoover,
M., Butman, D., Striegl, R., Mayorga, E., Humborg, C., Kortelainen, P.,
Dürr, H., Meybeck, M., Ciais, P., and Guth, P.: Global carbon dioxide
emissions from inland waters, Nature, 503, 355–359, https://doi.org/10.1038/nature12760,
2013.
Reynolds, C. S. and Descy, J.-P.: The production, biomass and structure of
phytoplankton in large rivers, Archiv für Hydrobiologie, 10, 161–187,
https://doi.org/10.1127/lr/10/1996/161, 1996.
Rhee, T. S., Kettle, A. J., and Andreae, M. O.: Methane and nitrous oxide
emissions from the ocean: A reassessment using basin-wide observations in the
Atlantic, J. Geophys. Res., 114, D12304, https://doi.org/10.1029/2008JD011662, 2009.
Rosentreter, J. A., Maher, D. T., Erler, D. V., Murray, R., and Eyre, B. D.:
Seasonal and temporal CO2 dynamics in three tropical mangrove creeks –
A revision of global mangrove CO2 emissions, Geochim. Cosmochim. Ac.,
222, 729–745, https://doi.org/10.1016/j.gca.2017.11.026, 2018.
Sarma, V. V. S. S., Viswanadham, R., Rao, G. D., Prasad, V. R., Kumar, B. S.
K., Naidu, S. A., Kumar, N. A., Rao, D. B., Sridevi, T., Krishna, M. S.,
Reddy, N. P. C., Sadhuram, Y., and Murty, T. V. R.: Carbon dioxide emissions
from Indian monsoonal estuaries, Geophys. Res. Lett., 39, L03602,
https://doi.org/10.1029/2011GL050709, 2012.
Smajgl, A., Toan, T. Q., Nhan, D. K., Ward, J., Trung, N. H., Tri, L. Q.,
Tri, V. P. D., and Vu, P. T.: Responding to rising sea levels in the Mekong
Delta, Nat. Clim. Change, 5, 167–174, https://doi.org/10.1038/nclimate2469, 2015.
Smith, S. V. and Key, G. S.: Carbon dioxide and metabolism in marine
environments, Limnol. Oceanogr., 20, 493–495, https://doi.org/10.4319/lo.1975.20.3.0493,
1975.
Stanley, E. H., Casson, N. J., Christel, S. T., Crawford, J. T., Loken, L.
C., and Oliver, S. K.: The ecology of methane in streams and rivers:
patterns, controls, and global significance, Ecol. Monogr., 86, 146–171,
https://doi.org/10.1890/15-1027, 2016.
Takagi, H., Tsurudome, C., Thao, N. D., Anh, L. T., Ty, T. V., and Tri, V. P.
D.: Ocean tide modelling for urban flood risk assessment in the Mekong Delta,
Hydrol. Res. Lett., 10, 21–26, https://doi.org/10.3178/hrl.10.21, 2016.
Testa, J. M., Kemp, W. M., Hopkinson, C. S., and Smith, S. V.: Ecosystem
Metabolism, in: Estuarine Ecology, 2nd Edn., edited by: Day, J. W., Crump, B.
C., Kemp, W. M., and Yáñez-Arancibia, A., John Wiley & Sons, Inc.,
Hoboken, NJ, USA, https://doi.org/10.1002/9781118412787.ch15, 2012.
Tong, P. H. S., Auda, Y., Populus, J., Aizpuru, M., Al Habshi, A., and
Blasco, F.: Assessment from space of mangroves evolution in the Mekong Delta,
in relation to extensive shrimp farming, Int. J. Remote Sens., 25,
4795–4812, https://doi.org/10.1080/01431160412331270858, 2010.
Tseng, H.-C., Chen, C.-T. A., Borges, A. V., Lai, C.-M., DelValls, T. A., and
Chang, Y.-C.: Methane in the South China Sea and the Western Philippine Sea,
Cont. Shelf Res., 135, 23–34, https://doi.org/10.1016/j.csr.2017.01.005, 2017.
Upstill-Goddard, R. C. and Barnes, J.: Methane emissions from UK estuaries:
re-evaluating the estuarine source of tropospheric methane from Europe. Mar.
Chem., 180, 14–23, https://doi.org/10.1016/j.marchem.2016.01.010, 2016.
Upstill-Goddard, R. C., Barnes, J., Frost, T., Punshon, S., and Owens, N. J.
P.: Methane in the Southern North Sea: low salinity inputs, estuarine removal
and atmospheric flux. Global Biogeochem. Cy., 14, 1205–1217,
https://doi.org/10.1029/1999GB001236, 2000.
Varis, O., Kummu, M., and Salmivaara, A.: Ten major river basins in monsoon
Asia-Pacific: an assessment of vulnerability, Appl. Geogr., 32, 441–454,
https://doi.org/10.1016/j.apgeog.2011.05.003, 2012.
Västilä, K., Kummu, M., Sangmanee, C., and Chinvanno, S.: Modelling
climate change impacts on the flood pulse in the Lower Mekong floodplains, J.
Water Climate Change, 1, 67–86, https://doi.org/10.2166/wcc.2010.008, 2010.
Wang, J. J., Lu, X. X., and Kummu, M.: Sediment loads estimate in the lower
Mekong River, River Res. Appl., 27, 22–46, https://doi.org/10.1002/rra.1337, 2011.
Wanninkhof, R.: Relationship between wind speed and gas exchange over the
ocean, J. Geophys. Res., 97, 7373–7382, https://doi.org/10.1029/92JC00188, 1992.
Weiss, R. F.: Carbon dioxide in water and seawater: the solubility of a
non-ideal gas, Mar. Chem., 2, 203–215, https://doi.org/10.1016/0304-4203(74)90015-2,
1974.
Weiss, R. F.: Determinations of carbon dioxide and methane by dual catalyst
flame ionization chromatography and nitrous oxide by electron capture
chromatography, J. Chromatogr. Sci., 19, 611–616,
https://doi.org/10.1093/chromsci/19.12.611, 1981.
Weiss, R. F. and Price, B. A.: Nitrous oxide solubility in water and
seawater, Mar. Chem., 8, 347–359, 1980.
Whitton, B. A.: River Ecology – Studies in Ecology, Blackwell Scientific
Publications, Oxford, London, Edinburgh, Melbourne, 725 pp., 1975.
Yamamoto, S., Alcauskas, J. B., and Crozier, T. E.: Solubility of methane in
distilled water and seawater, J. Chem. Eng. Data, 21, 78–80,
https://doi.org/10.1021/je60068a029, 1976.
Zhai, W., Dai, M., and Guo, X.: Carbonate system and CO2 degassing
fluxes in the inner estuary of Changjiang (Yangtze) River, China, Mar. Chem.,
107, 342–356, https://doi.org/10.1016/j.marchem.2007.02.011, 2007.
Zhang, G., Zhang, J., Liu, S., Ren, J., Xu, J., and Zhang, F.: Methane in the
Changjiang (Yangtze River) Estuary and its adjacent marine area: riverine
input, sediment release and atmospheric fluxes, Biogeochemistry, 91, 71–84,
https://doi.org/10.1007/s10533-008-9259-7, 2008.
Zhou, H., Yin, X., Yang, Q., Wang, H., Wu, Z., and Bao, S.: Distribution,
source and flux of methane in the western Pearl River Estuary and northern
South China Sea, Mar. Chem., 117, 21–31, https://doi.org/10.1016/j.marchem.2009.07.011,
2009.
Short summary
The Mekong River is among the largest on Earth and is vital for the economy of Vietnam and South East Asia and the livelihood of the local population (70 million across six countries). Numerous dams for hydropower are planned, which will affect the delivery of water and sediments to the Mekong delta, with numerous possible consequences. We report the dynamics of two greenhouse gases (CO2 and CH4) in the Mekong delta that can be used as a reference state to evaluate future changes.
The Mekong River is among the largest on Earth and is vital for the economy of Vietnam and South...
Special issue
Altmetrics
Final-revised paper
Preprint