Articles | Volume 16, issue 19
https://doi.org/10.5194/bg-16-3801-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-16-3801-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
07 Oct 2019
Research article |
| 07 Oct 2019
| 07 Oct 2019
Variations in dissolved greenhouse gases (CO2, CH4, N2O) in the Congo River network overwhelmingly driven by fluvial-wetland connectivity
Alberto V. Borges
CORRESPONDING AUTHOR
Chemical Oceanography Unit, University of Liège, Liège,
Belgium
François Darchambeau
Chemical Oceanography Unit, University of Liège, Liège,
Belgium
present address: Direction Générale Opérationnelle
Agriculture, Ressources Naturelles et Environnement, Service Publique de
Wallonie, Jambes, Belgium
Thibault Lambert
Chemical Oceanography Unit, University of Liège, Liège,
Belgium
present address: University of Lausanne, Institute of Earth Surface
Dynamics, Lausanne, Switzerland
Cédric Morana
Department of Earth and Environmental Sciences, KU Leuven, Leuven,
Belgium
George H. Allen
Department of Geography, Texas A&M University, College Station, Texas, USA
Ernest Tambwe
Université de Kisangani, Centre de Surveillance de la
Biodiversité, Kisangani, Democratic Republic of the Congo
Alfred Toengaho Sembaito
Université de Kisangani, Centre de Surveillance de la
Biodiversité, Kisangani, Democratic Republic of the Congo
Taylor Mambo
Université de Kisangani, Centre de Surveillance de la
Biodiversité, Kisangani, Democratic Republic of the Congo
José Nlandu Wabakhangazi
Congo Atomic Energy Commission, Kinshasa, Democratic Republic of the Congo
Jean-Pierre Descy
Chemical Oceanography Unit, University of Liège, Liège,
Belgium
Cristian R. Teodoru
Department of Earth and Environmental Sciences, KU Leuven, Leuven,
Belgium
present address: Eidgenössische Technische
Hochschule Zürich, Zürich, Switzerland
Steven Bouillon
Department of Earth and Environmental Sciences, KU Leuven, 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.
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.
Alberto V. Borges, Gwenaël Abril, and Steven Bouillon
Biogeosciences, 15, 1093–1114, https://doi.org/10.5194/bg-15-1093-2018, https://doi.org/10.5194/bg-15-1093-2018, 2018
Short summary
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.
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
Thibault Lambert, Rémi Dupas, and Patrick Durand
Biogeosciences, 21, 4533–4547, https://doi.org/10.5194/bg-21-4533-2024, https://doi.org/10.5194/bg-21-4533-2024, 2024
Short summary
Short summary
This study investigates dissolved organic carbon (DOC) export in headwater catchments. Results show small links between DOC, nitrates, and the iron cycle throughout the year, calling into question our current conceptualization of DOC export at the catchment scale. Indeed, this study evidences that the winter period, referred as a non-productive period in our current conceptual model, acts as an active period for DOC production in riparian soils and DOC export toward stream waters.
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.
Bernhard Lehner, Mira Anand, Etienne Fluet-Chouinard, Florence Tan, Filipe Aires, George H. Allen, Pilippe Bousquet, Josep G. Canadell, Nick Davidson, C. Max Finlayson, Thomas Gumbricht, Lammert Hilarides, Gustaf Hugelius, Robert B. Jackson, Maartje C. Korver, Peter B. McIntyre, Szabolcs Nagy, David Olefeldt, Tamlin M. Pavelsky, Jean-Francois Pekel, Benjamin Poulter, Catherine Prigent, Jida Wang, Thomas A. Worthington, Dai Yamazaki, and Michele Thieme
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2024-204, https://doi.org/10.5194/essd-2024-204, 2024
Revised manuscript accepted for ESSD
Short summary
Short summary
The Global Lakes and Wetlands Database (GLWD) version 2 distinguishes a total of 33 non-overlapping wetland classes, providing a static map of the world’s inland surface waters. It contains cell fractions of wetland extents per class at a grid cell resolution of ~500 m. The total combined extent of all classes including all inland and coastal waterbodies and wetlands of all inundation frequencies—that is, the maximum extent—covers 18.2 million km2, equivalent to 13.4 % of total global land area.
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.
Jida Wang, Blake A. Walter, Fangfang Yao, Chunqiao Song, Meng Ding, Abu Sayeed Maroof, Jingying Zhu, Chenyu Fan, Jordan M. McAlister, Safat Sikder, Yongwei Sheng, George H. Allen, Jean-François Crétaux, and Yoshihide Wada
Earth Syst. Sci. Data, 14, 1869–1899, https://doi.org/10.5194/essd-14-1869-2022, https://doi.org/10.5194/essd-14-1869-2022, 2022
Short summary
Short summary
Improved water infrastructure data on dams and reservoirs remain to be critical to hydrologic modeling, energy planning, and environmental conservation. We present a new global dataset, GeoDAR, that includes nearly 25 000 georeferenced dam points and their associated reservoir boundaries. A majority of these features can be linked to the register of the International Commission on Large Dams, extending the potential of registered attribute information for spatially explicit applications.
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.
Thibault Lambert, Pascal Perolo, Nicolas Escoffier, and Marie-Elodie Perga
Biogeosciences, 19, 187–200, https://doi.org/10.5194/bg-19-187-2022, https://doi.org/10.5194/bg-19-187-2022, 2022
Short summary
Short summary
The bacterial mineralization of dissolved organic matter (DOM) in inland waters contributes to CO2 emissions to the atmosphere. Human activities affect DOM sources. However, the implications on DOM mineralization are poorly known. Combining sampling and incubations, we showed that higher bacterial respiration in agro-urban streams related to a labile pool from aquatic origin. Therefore, human activities may have a limited impact on the net carbon exchanges between inland waters and atmosphere.
Pascal Perolo, Bieito Fernández Castro, Nicolas Escoffier, Thibault Lambert, Damien Bouffard, and Marie-Elodie Perga
Earth Syst. Dynam., 12, 1169–1189, https://doi.org/10.5194/esd-12-1169-2021, https://doi.org/10.5194/esd-12-1169-2021, 2021
Short summary
Short summary
Wind blowing over the ocean creates waves that, by increasing the level of turbulence, promote gas exchange at the air–water interface. In this study, for the first time, we measured enhanced gas exchanges by wind-induced waves at the surface of a large lake. We adapted an ocean-based model to account for the effect of surface waves on gas exchange in lakes. We finally show that intense wind events with surface waves contribute disproportionately to the annual CO2 gas flux in a large lake.
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.
Marie-Sophie Maier, Cristian R. Teodoru, and Bernhard Wehrli
Biogeosciences, 18, 1417–1437, https://doi.org/10.5194/bg-18-1417-2021, https://doi.org/10.5194/bg-18-1417-2021, 2021
Short summary
Short summary
Based on a 2-year monitoring study, we found that the freshwater system of the Danube Delta, Romania, releases carbon dioxide and methane to the atmosphere. The amount of carbon released depends on the freshwater feature (river branches, channels and lakes), season and hydrologic condition, affecting the exchange with the wetland. Spatial upscaling should therefore consider these factors. Furthermore, the Danube Delta increases the amount of carbon reaching the Black Sea via the Danube River.
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.
Roberto Grilli, François Darchambeau, Jérôme Chappellaz, Ange Mugisha, Jack Triest, and Augusta Umutoni
Geosci. Instrum. Method. Data Syst., 9, 141–151, https://doi.org/10.5194/gi-9-141-2020, https://doi.org/10.5194/gi-9-141-2020, 2020
Short summary
Short summary
We report the results from the deployment of a newly developed in situ sensor for dissolved gas measurements. Its adaptation to high gas concentrations and dissolved gas pressures was proven. The campaign leads to a first continuous profile of methane on the first 150 m and allowed us to compare the data with previous measurements. The fast response of the instrument makes this technique a good candidate for regular monitoring of those type of lakes, for anticipating disastrous gas eruptions.
Stephen Coss, Michael Durand, Yuchan Yi, Yuanyuan Jia, Qi Guo, Stephen Tuozzolo, C. K. Shum, George H. Allen, Stéphane Calmant, and Tamlin Pavelsky
Earth Syst. Sci. Data, 12, 137–150, https://doi.org/10.5194/essd-12-137-2020, https://doi.org/10.5194/essd-12-137-2020, 2020
Short summary
Short summary
We present a new radar-altimeter-satellite-measured river surface height dataset. Our novel approach is broadly applicable rather than location specific. We were able to measure rivers that account for > 34 % of global drainage area with an accuracy comparable to much of the established literature. 389 of our 932 measurement locations include river gage validation. We have focused our efforts on creating a consistent, well-documented data product to encourage use by the broader science community.
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.
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.
Alberto V. Borges, Gwenaël Abril, and Steven Bouillon
Biogeosciences, 15, 1093–1114, https://doi.org/10.5194/bg-15-1093-2018, https://doi.org/10.5194/bg-15-1093-2018, 2018
Short summary
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.
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.
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
L. Jeanneau, M. Denis, A.-C. Pierson-Wickmann, G. Gruau, T. Lambert, and P. Petitjean
Biogeosciences, 12, 4333–4343, https://doi.org/10.5194/bg-12-4333-2015, https://doi.org/10.5194/bg-12-4333-2015, 2015
Short summary
Short summary
The origin of stream dissolved organic matter (DOM) in a lowland headwater catchment was investigated using high-frequency sampling combined with chemical biomarker analysis. Inter-storm stream DOM corresponds to the flushing of soil DOM reservoirs, while storm stream DOM would also result from three additional mechanisms: biofilm destabilization, surface and sub-surface erosion.
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. Lambert, A.-C. Pierson-Wickmann, G. Gruau, A. Jaffrezic, P. Petitjean, J. N. Thibault, and L. Jeanneau
Biogeosciences, 11, 3043–3056, https://doi.org/10.5194/bg-11-3043-2014, https://doi.org/10.5194/bg-11-3043-2014, 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: Greenhouse Gases
Intercomparison of biogenic CO2 flux models in four urban parks in the city of Zurich
CO2 flux characteristics of the open savanna and its response to environmental factors in the dry–hot valley of Jinsha River, China
Rising Arctic seas and thawing permafrost: uncovering the carbon cycle impact in a thermokarst lagoon system in the outer Mackenzie Delta, Canada
Modelling decadal trends and the impact of extreme events on carbon fluxes in a temperate deciduous forest using a terrestrial biosphere model
Surface CO2 gradients challenge conventional CO2 emission quantification in lentic water bodies under calm conditions
Spatiotemporal variability of CO2, N2O and CH4 fluxes from a semi-deciduous tropical forest soil in the Congo Basin
Eddy-covariance fluxes of CO2, CH4 and N2O in a drained peatland forest after clear-cutting
Eddy covariance evaluation of ecosystem fluxes at a temperate saltmarsh in Victoria, Australia, shows large CO2 uptake
Interferences caused by the biogeochemical methane cycle in peats during the assessment of abandoned oil wells
Carbon sequestration in different urban vegetation types in Southern Finland
Proglacial methane emissions driven by meltwater and groundwater flushing in a high-Arctic glacial catchment
Seasonal and interannual variability in CO2 fluxes in southern Africa seen by GOSAT
Air temperature and precipitation constraining the modelled wetland methane emissions in a boreal region in northern Europe
Ensemble estimates of global wetland methane emissions over 2000–2020
Seasonal carbon fluxes from vegetation and soil in a Mediterranean non-tidal salt marsh
Explainable machine learning for modeling of net ecosystem exchange in boreal forests
Dynamics of CO2 and CH4 fluxes in Red Sea mangrove soils
Nitrous oxide (N2O) in Macquarie Harbour, Tasmania
Technical note: A low-cost, automatic soil–plant–atmosphere enclosure system to investigate CO2 and evapotranspiration flux dynamics
Tidal influence on carbon dioxide and methane fluxes from tree stems and soils in mangrove forests
Drought conditions disrupt atmospheric carbon uptake in a Mediterranean saline lake
Physicochemical perturbation increases nitrous oxide production from denitrification in soils and sediments
Carbon degradation and mobilisation potentials of thawing permafrost peatlands in northern Norway inferred from laboratory incubations
Seasonal dynamics and regional distribution patterns of CO2 and CH4 in the north-eastern Baltic Sea
Interannual and seasonal variability of the air–sea CO2 exchange at Utö in the coastal region of the Baltic Sea
CO2 emissions of drained coastal peatlands in the Netherlands and potential emission reduction by water infiltration systems
Influence of wind strength and direction on diffusive methane fluxes and atmospheric methane concentrations above the North Sea
Using eddy covariance observations to determine the carbon sequestration characteristics of subalpine forests in the Qinghai–Tibet Plateau
Isotopomer labeling and oxygen dependence of hybrid nitrous oxide production
The emission of CO from tropical rainforest soils
Modelling CO2 and N2O emissions from soils in silvopastoral systems of the West African Sahelian band
A case study on topsoil removal and rewetting for paludiculture: effect on biogeochemistry and greenhouse gas emissions from Typha latifolia, Typha angustifolia, and Azolla filiculoides
Observations of methane net sinks in the Arctic tundra
Assessing improvements in global ocean pCO2 machine learning reconstructions with Southern Ocean autonomous sampling
Timescale dependence of airborne fraction and underlying climate–carbon-cycle feedbacks for weak perturbations in CMIP5 models
Technical note: Preventing CO2 overestimation from mercuric or copper(II) chloride preservation of dissolved greenhouse gases in freshwater samples
Exploring temporal and spatial variation of nitrous oxide flux using several years of peatland forest automatic chamber data
Diurnal versus spatial variability of greenhouse gas emissions from an anthropogenically modified lowland river in Germany
Regional assessment and uncertainty analysis of carbon and nitrogen balances at cropland scale using the ecosystem model LandscapeDNDC
Resolving heterogeneous fluxes from tundra halves the growing season carbon budget
Lawns and meadows in urban green space – a comparison from perspectives of greenhouse gases, drought resilience and plant functional types
Large contribution of soil N2O emission to the global warming potential of a large-scale oil palm plantation despite changing from conventional to reduced management practices
Identifying landscape hot and cold spots of soil greenhouse gas fluxes by combining field measurements and remote sensing data
Enhanced Southern Ocean CO2 outgassing as a result of stronger and poleward shifted southern hemispheric westerlies
Spatial and temporal variability of methane emissions and environmental conditions in a hyper-eutrophic fishpond
Optical and radar Earth observation data for upscaling methane emissions linked to permafrost degradation in sub-Arctic peatlands in northern Sweden
Herbivore–shrub interactions influence ecosystem respiration and biogenic volatile organic compound composition in the subarctic
Methane emissions due to reservoir flushing: a significant emission pathway?
Carbon dioxide and methane fluxes from mounds of African fungus-growing termites
Diel and seasonal methane dynamics in the shallow and turbulent Wadden Sea
Stavros Stagakis, Dominik Brunner, Junwei Li, Leif Backman, Anni Karvonen, Lionel Constantin, Leena Järvi, Minttu Havu, Jia Chen, Sophie Emberger, and Liisa Kulmala
Biogeosciences, 22, 2133–2161, https://doi.org/10.5194/bg-22-2133-2025, https://doi.org/10.5194/bg-22-2133-2025, 2025
Short summary
Short summary
The balance between CO2 uptake and emissions from urban green areas is still not well understood. This study evaluated for the first time the urban park CO2 exchange simulations with four different types of biosphere model by comparing them with observations. Even though some advantages and disadvantages of the different model types were identified, there was no strong evidence that more complex models performed better than simple ones.
Chaolei Yang, Yufeng Tian, Jingqi Cui, Guangxiong He, Jingyuan Li, Canfeng Li, Haichuang Duan, Zong Wei, Liu Yan, Xin Xia, Yong Huang, Aihua Jiang, and Yuwen Feng
Biogeosciences, 22, 2097–2114, https://doi.org/10.5194/bg-22-2097-2025, https://doi.org/10.5194/bg-22-2097-2025, 2025
Short summary
Short summary
Due to the influence of extreme-drought events in southwest China, the carbon sequestration capacity of the open savanna in the dry–hot valley of the Jinsha River has been significantly diminished, with soil water content being the key environmental factor governing CO2 flux. Under the climate scenario where the frequency and severity of extreme droughts are expected to continue increasing, the CO2 emissions from the open savanna are also anticipated to rise persistently.
Maren Jenrich, Juliane Wolter, Susanne Liebner, Christian Knoblauch, Guido Grosse, Fiona Giebeler, Dustin Whalen, and Jens Strauss
Biogeosciences, 22, 2069–2086, https://doi.org/10.5194/bg-22-2069-2025, https://doi.org/10.5194/bg-22-2069-2025, 2025
Short summary
Short summary
Climate warming in the Arctic is causing the erosion of permafrost coasts and the transformation of permafrost lakes into lagoons. To understand how this affects greenhouse gas (GHG) emissions, we studied carbon dioxide (CO₂) and methane (CH₄) production in lagoons with varying sea connections. Younger lagoons produce more CH₄, while CO₂ increases under more marine conditions. Flooding of permafrost lowlands due to rising sea levels may lead to higher GHG emissions from Arctic coasts in future.
Tea Thum, Tuuli Miinalainen, Outi Seppälä, Holly Croft, Cheryl Rogers, Ralf Staebler, Silvia Caldararu, and Sönke Zaehle
Biogeosciences, 22, 1781–1807, https://doi.org/10.5194/bg-22-1781-2025, https://doi.org/10.5194/bg-22-1781-2025, 2025
Short summary
Short summary
Climate change has the potential to influence the carbon sequestration potential of terrestrial ecosystems, and here the nitrogen cycle is also important. We used the terrestrial biosphere model QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system) in a mixed deciduous forest in Canada. We investigated the usefulness of using the leaf area index and leaf chlorophyll content to improve the parameterization of the model. This work paves the way for using spaceborne observations in model parameterizations, also including information on the nitrogen cycle.
Patrick Aurich, Uwe Spank, and Matthias Koschorreck
Biogeosciences, 22, 1697–1709, https://doi.org/10.5194/bg-22-1697-2025, https://doi.org/10.5194/bg-22-1697-2025, 2025
Short summary
Short summary
Lakes can be sources and sinks of the greenhouse gas carbon dioxide. The gas exchange between the atmosphere and the water can be measured by taking gas samples from them. However, the depth of water samples is not well defined, which may cause errors. We hypothesized that gradients of CO2 concentrations develop under the surface when wind speeds are very low. Our measurements show that such a gradient can occur on calm nights, potentially shifting lakes from a CO2 sink to a source.
Roxanne Daelman, Marijn Bauters, Matti Barthel, Emmanuel Bulonza, Lodewijk Lefevre, José Mbifo, Johan Six, Klaus Butterbach-Bahl, Benjamin Wolf, Ralf Kiese, and Pascal Boeckx
Biogeosciences, 22, 1529–1542, https://doi.org/10.5194/bg-22-1529-2025, https://doi.org/10.5194/bg-22-1529-2025, 2025
Short summary
Short summary
The increase in atmospheric concentrations of several greenhouse gases (GHGs) since 1750 is attributed to human activity. However, natural ecosystems, such as tropical forests, also contribute to GHG budgets. The Congo Basin hosts the second largest tropical forest and is understudied. In this study, measurements of soil GHG exchange were carried out during 16 months in a tropical forest in the Congo Basin. Overall, the soil acted as a major source of CO2 and N2O and a minor sink of CH4.
Olli-Pekka Tikkasalo, Olli Peltola, Pavel Alekseychik, Juha Heikkinen, Samuli Launiainen, Aleksi Lehtonen, Qian Li, Eduardo Martínez-García, Mikko Peltoniemi, Petri Salovaara, Ville Tuominen, and Raisa Mäkipää
Biogeosciences, 22, 1277–1300, https://doi.org/10.5194/bg-22-1277-2025, https://doi.org/10.5194/bg-22-1277-2025, 2025
Short summary
Short summary
The emissions of greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) were measured from a clear-cut peatland forest site. The measurements covered the whole year of 2022, which was the second growing season after the clear-cut. The site was a strong GHG source, and the highest emissions came from CO2, followed by N2O and CH4. A statistical model that included information on different surfaces at the site was developed to unravel surface-type-specific GHG fluxes.
Ruth Reef, Edoardo Daly, Tivanka Anandappa, Eboni-Jane Vienna-Hallam, Harriet Robertson, Matthew Peck, and Adrien Guyot
Biogeosciences, 22, 1149–1162, https://doi.org/10.5194/bg-22-1149-2025, https://doi.org/10.5194/bg-22-1149-2025, 2025
Short summary
Short summary
Studies show that saltmarshes excel at capturing carbon from the atmosphere. In this study, we measured CO2 flux in an Australian temperate saltmarsh on French Island. The temperate saltmarsh exhibited strong seasonality. During the warmer growing season, the saltmarsh absorbed 10.5 g CO2 m−2 on average daily from the atmosphere. Even in winter, when plants were dormant, it continued to be a CO2 sink, albeit a smaller one. Cool temperatures and high cloud cover inhibit carbon sequestration.
Sebastian F. A. Jordan, Stefan Schloemer, Martin Krüger, Tanja Heffner, Marcus A. Horn, and Martin Blumenberg
Biogeosciences, 22, 809–830, https://doi.org/10.5194/bg-22-809-2025, https://doi.org/10.5194/bg-22-809-2025, 2025
Short summary
Short summary
Using a multilayer approach, we studied the methane flux, soil gas composition, and isotopic signatures of soil methane and carbon dioxide at eight cut and buried abandoned oil wells in a peat-rich area of northern Germany. The detected methane emissions were of biogenic, peat origin and were not associated with the abandoned wells. Additional microbial analysis and methane oxidation rate measurements demonstrated a high methane emission mitigation potential in the studied peat soils.
Laura Thölix, Leif Backman, Minttu Havu, Esko Karvinen, Jesse Soininen, Justine Trémeau, Olli Nevalainen, Joyson Ahongshangbam, Leena Järvi, and Liisa Kulmala
Biogeosciences, 22, 725–749, https://doi.org/10.5194/bg-22-725-2025, https://doi.org/10.5194/bg-22-725-2025, 2025
Short summary
Short summary
Cities aim for carbon neutrality and seek to understand urban vegetation's role as a carbon sink. Direct measurements are challenging, so models are used to estimate the urban carbon cycle. We evaluated model performance at estimating carbon sequestration in lawns, park trees, and urban forests in Helsinki, Finland. Models captured seasonal and annual variations well. Trees had higher sequestration rates than lawns, and irrigation often enhanced carbon sinks.
Gabrielle E. Kleber, Leonard Magerl, Alexandra V. Turchyn, Stefan Schloemer, Mark Trimmer, Yizhu Zhu, and Andrew Hodson
Biogeosciences, 22, 659–674, https://doi.org/10.5194/bg-22-659-2025, https://doi.org/10.5194/bg-22-659-2025, 2025
Short summary
Short summary
Our research on Svalbard shows that glacier melt rivers can transport large amounts of methane, a potent greenhouse gas. By studying a glacier over one summer, we found that its river was highly concentrated in methane, suggesting that rivers could provide a significant source of methane emissions as the Arctic warms and glaciers melt. This is the first time such emissions have been measured on Svalbard, indicating a wider environmental concern as such processes are occurring across the Arctic.
Eva-Marie Metz, Sanam Noreen Vardag, Sourish Basu, Martin Jung, and André Butz
Biogeosciences, 22, 555–584, https://doi.org/10.5194/bg-22-555-2025, https://doi.org/10.5194/bg-22-555-2025, 2025
Short summary
Short summary
We estimate CO2 fluxes in semiarid southern Africa from 2009 to 2018 based on satellite CO2 measurements and atmospheric inverse modeling. By selecting process-based vegetation models, which agree with the satellite CO2 fluxes, we find that soil respiration mainly drives the seasonality, whereas photosynthesis substantially influences the interannual variability. Our study emphasizes the need for better representation of the response of semiarid ecosystems to soil rewetting in vegetation models.
Tuula Aalto, Aki Tsuruta, Jarmo Mäkelä, Jurek Müller, Maria Tenkanen, Eleanor Burke, Sarah Chadburn, Yao Gao, Vilma Mannisenaho, Thomas Kleinen, Hanna Lee, Antti Leppänen, Tiina Markkanen, Stefano Materia, Paul A. Miller, Daniele Peano, Olli Peltola, Benjamin Poulter, Maarit Raivonen, Marielle Saunois, David Wårlind, and Sönke Zaehle
Biogeosciences, 22, 323–340, https://doi.org/10.5194/bg-22-323-2025, https://doi.org/10.5194/bg-22-323-2025, 2025
Short summary
Short summary
Wetland methane responses to temperature and precipitation were studied in a boreal wetland-rich region in northern Europe using ecosystem models, atmospheric inversions, and upscaled flux observations. The ecosystem models differed in their responses to temperature and precipitation and in their seasonality. However, multi-model means, inversions, and upscaled fluxes had similar seasonality, and they suggested co-limitation by temperature and precipitation.
Zhen Zhang, Benjamin Poulter, Joe R. Melton, William J. Riley, George H. Allen, David J. Beerling, Philippe Bousquet, Josep G. Canadell, Etienne Fluet-Chouinard, Philippe Ciais, Nicola Gedney, Peter O. Hopcroft, Akihiko Ito, Robert B. Jackson, Atul K. Jain, Katherine Jensen, Fortunat Joos, Thomas Kleinen, Sara H. Knox, Tingting Li, Xin Li, Xiangyu Liu, Kyle McDonald, Gavin McNicol, Paul A. Miller, Jurek Müller, Prabir K. Patra, Changhui Peng, Shushi Peng, Zhangcai Qin, Ryan M. Riggs, Marielle Saunois, Qing Sun, Hanqin Tian, Xiaoming Xu, Yuanzhi Yao, Yi Xi, Wenxin Zhang, Qing Zhu, Qiuan Zhu, and Qianlai Zhuang
Biogeosciences, 22, 305–321, https://doi.org/10.5194/bg-22-305-2025, https://doi.org/10.5194/bg-22-305-2025, 2025
Short summary
Short summary
This study assesses global methane emissions from wetlands between 2000 and 2020 using multiple models. We found that wetland emissions increased by 6–7 Tg CH4 yr-1 in the 2010s compared to the 2000s. Rising temperatures primarily drove this increase, while changes in precipitation and CO2 levels also played roles. Our findings highlight the importance of wetlands in the global methane budget and the need for continuous monitoring to understand their impact on climate change.
Lorena Carrasco-Barea, Dolors Verdaguer, Maria Gispert, Xavier D. Quintana, Hélène Bourhis, and Laura Llorens
Biogeosciences, 22, 289–304, https://doi.org/10.5194/bg-22-289-2025, https://doi.org/10.5194/bg-22-289-2025, 2025
Short summary
Short summary
Carbon dioxide fluxes have been measured seasonally in four plant species in a Mediterranean non-tidal salt marsh, highlighting the high carbon removal potential that these species have. Carbon dioxide and methane emissions from soil showed high variability among the habitats studied, and they were generally higher than those observed in tidal salt marshes. Our results are important for making more accurate predictions regarding carbon emissions from these ecosystems.
Ekaterina Ezhova, Topi Laanti, Anna Lintunen, Pasi Kolari, Tuomo Nieminen, Ivan Mammarella, Keijo Heljanko, and Markku Kulmala
Biogeosciences, 22, 257–288, https://doi.org/10.5194/bg-22-257-2025, https://doi.org/10.5194/bg-22-257-2025, 2025
Short summary
Short summary
Machine learning (ML) models are gaining popularity in biogeosciences. They are applied as gap-filling methods and used to upscale carbon fluxes to larger areas. Here we use explainable artificial intelligence (XAI) methods to elucidate the performance of machine learning models for carbon dioxide fluxes in boreal forests. We show that statistically equal models treat input variables differently. XAI methods can help scientists make informed decisions when applying ML models in their research.
Jessica Breavington, Alexandra Steckbauer, Chuancheng Fu, Mongi Ennasri, and Carlos M. Duarte
Biogeosciences, 22, 117–134, https://doi.org/10.5194/bg-22-117-2025, https://doi.org/10.5194/bg-22-117-2025, 2025
Short summary
Short summary
Mangrove carbon storage in the Red Sea is lower than average due to challenging growth conditions. We collected mangrove soil cores over multiple seasons to measure greenhouse gas (GHG) flux of carbon dioxide and methane. GHG emissions are a small offset to mangrove carbon storage overall but punctuated by periods of high emission. This variation is linked to environmental and soil properties, which were also measured. The findings aid understanding of GHG dynamics in arid mangrove ecosystems.
Johnathan Daniel Maxey, Neil D. Hartstein, Hermann W. Bange, and Moritz Müller
Biogeosciences, 21, 5613–5637, https://doi.org/10.5194/bg-21-5613-2024, https://doi.org/10.5194/bg-21-5613-2024, 2024
Short summary
Short summary
The distribution of N2O in fjord-like estuaries is poorly described in the Southern Hemisphere. Our study describes N2O distribution and its drivers in one such system in Macquarie Harbour, Tasmania. Water samples were collected seasonally in 2022 and 2023. Results show the system removes atmospheric N2O when river flow is high, whereas the system emits N2O when the river flow is low. N2O generated in basins is intercepted by the surface water and exported to the ocean during high river flow.
Wael Al Hamwi, Maren Dubbert, Jörg Schaller, Matthias Lück, Marten Schmidt, and Mathias Hoffmann
Biogeosciences, 21, 5639–5651, https://doi.org/10.5194/bg-21-5639-2024, https://doi.org/10.5194/bg-21-5639-2024, 2024
Short summary
Short summary
We present a fully automatic, low-cost soil–plant enclosure system to monitor CO2 and evapotranspiration fluxes within greenhouse experiments. It operates in two modes: independent, using low-cost sensors, and dependent, where multiple chambers connect to a single gas analyzer via a low-cost multiplexer. This system provides precise, accurate measurements and high temporal resolution, enabling comprehensive monitoring of plant–soil responses to various treatments and conditions.
Zhao-Jun Yong, Wei-Jen Lin, Chiao-Wen Lin, and Hsing-Juh Lin
Biogeosciences, 21, 5247–5260, https://doi.org/10.5194/bg-21-5247-2024, https://doi.org/10.5194/bg-21-5247-2024, 2024
Short summary
Short summary
We measured CO2 and CH4 fluxes from mangrove stems and soils of Avicennia marina and Kandelia obovata during tidal cycles. Both stem types served as CO2 and CH4 sources, emitting less CH4 than soils, with no difference in CO2 flux. While A. marina stems showed increased CO2 fluxes from low to high tides, they acted as a CH4 sink before flooding and as a source after ebbing. However, K. obovata stems showed no flux pattern. This study highlights the need to consider tidal influence and species.
Ihab Alfadhel, Ignacio Peralta-Maraver, Isabel Reche, Enrique P. Sánchez-Cañete, Sergio Aranda-Barranco, Eva Rodríguez-Velasco, Andrew S. Kowalski, and Penélope Serrano-Ortiz
Biogeosciences, 21, 5117–5129, https://doi.org/10.5194/bg-21-5117-2024, https://doi.org/10.5194/bg-21-5117-2024, 2024
Short summary
Short summary
Inland saline lakes are crucial in the global carbon cycle, but increased droughts may alter their carbon exchange capacity. We measured CO2 and CH4 fluxes in a Mediterranean saline lake using the eddy covariance method under dry and wet conditions. We found the lake acts as a carbon sink during wet periods but not during droughts. These results highlight the importance of saline lakes in carbon sequestration and their vulnerability to climate-change-induced droughts.
Nathaniel B. Weston, Cynthia Troy, Patrick J. Kearns, Jennifer L. Bowen, William Porubsky, Christelle Hyacinthe, Christof Meile, Philippe Van Cappellen, and Samantha B. Joye
Biogeosciences, 21, 4837–4851, https://doi.org/10.5194/bg-21-4837-2024, https://doi.org/10.5194/bg-21-4837-2024, 2024
Short summary
Short summary
Nitrous oxide (N2O) is a potent greenhouse and ozone-depleting gas produced largely from microbial nitrogen cycling processes, and human activities have resulted in increases in atmospheric N2O. We investigate the role of physical and chemical disturbances to soils and sediments in N2O production. We demonstrate that physicochemical perturbation increases N2O production, microbial community adapts over time, and initial perturbation appears to confer resilience to subsequent disturbance.
Sigrid Trier Kjær, Sebastian Westermann, Nora Nedkvitne, and Peter Dörsch
Biogeosciences, 21, 4723–4737, https://doi.org/10.5194/bg-21-4723-2024, https://doi.org/10.5194/bg-21-4723-2024, 2024
Short summary
Short summary
Permafrost peatlands are thawing due to climate change, releasing large quantities of carbon that degrades upon thawing and is released as CO2, CH4 or dissolved organic carbon (DOC). We incubated thawed Norwegian permafrost peat plateaus and thermokarst pond sediment found next to permafrost for up to 350 d to measure carbon loss. CO2 production was initially the highest, whereas CH4 production increased over time. The largest carbon loss was measured at the top of the peat plateau core as DOC.
Silvie Lainela, Erik Jacobs, Stella-Theresa Luik, Gregor Rehder, and Urmas Lips
Biogeosciences, 21, 4495–4519, https://doi.org/10.5194/bg-21-4495-2024, https://doi.org/10.5194/bg-21-4495-2024, 2024
Short summary
Short summary
We evaluate the variability of carbon dioxide and methane in the surface layer of the north-eastern basins of the Baltic Sea in 2018. We show that the shallower coastal areas have considerably higher spatial variability and seasonal amplitude of surface layer pCO2 and cCH4 than measured in the offshore areas of the Baltic Sea. Despite this high variability, caused mostly by coastal physical processes, the average annual air–sea CO2 fluxes differed only marginally between the sub-basins.
Martti Honkanen, Mika Aurela, Juha Hatakka, Lumi Haraguchi, Sami Kielosto, Timo Mäkelä, Jukka Seppälä, Simo-Matti Siiriä, Ken Stenbäck, Juha-Pekka Tuovinen, Pasi Ylöstalo, and Lauri Laakso
Biogeosciences, 21, 4341–4359, https://doi.org/10.5194/bg-21-4341-2024, https://doi.org/10.5194/bg-21-4341-2024, 2024
Short summary
Short summary
The exchange of CO2 between the sea and the atmosphere was studied in the Archipelago Sea, Baltic Sea, in 2017–2021, using an eddy covariance technique. The sea acted as a net source of CO2 with an average yearly emission of 27.1 gC m-2 yr-1, indicating that the marine ecosystem respired carbon that originated elsewhere. The yearly CO2 emission varied between 18.2–39.2 gC m-2 yr-1, mostly due to the yearly variation of ecosystem carbon uptake.
Ralf C. H. Aben, Daniël van de Craats, Jim Boonman, Stijn H. Peeters, Bart Vriend, Coline C. F. Boonman, Ype van der Velde, Gilles Erkens, and Merit van den Berg
Biogeosciences, 21, 4099–4118, https://doi.org/10.5194/bg-21-4099-2024, https://doi.org/10.5194/bg-21-4099-2024, 2024
Short summary
Short summary
Drained peatlands cause high CO2 emissions. We assessed the effectiveness of subsurface water infiltration systems (WISs) in reducing CO2 emissions related to increases in water table depth (WTD) on 12 sites for up to 4 years. Results show WISs markedly reduced emissions by 2.1 t CO2-C ha-1 yr-1. The relationship between the amount of carbon above the WTD and CO2 emission was stronger than the relationship between WTD and emission. Long-term monitoring is crucial for accurate emission estimates.
Ingeborg Bussmann, Eric P. Achterberg, Holger Brix, Nicolas Brüggemann, Götz Flöser, Claudia Schütze, and Philipp Fischer
Biogeosciences, 21, 3819–3838, https://doi.org/10.5194/bg-21-3819-2024, https://doi.org/10.5194/bg-21-3819-2024, 2024
Short summary
Short summary
Methane (CH4) is an important greenhouse gas and contributes to climate warming. However, the input of CH4 from coastal areas to the atmosphere is not well defined. Dissolved and atmospheric CH4 was determined at high spatial resolution in or above the North Sea. The atmospheric CH4 concentration was mainly influenced by wind direction. With our detailed study on the spatial distribution of CH4 fluxes we were able to provide a detailed and more realistic estimation of coastal CH4 fluxes.
Niu Zhu, Jinniu Wang, Dongliang Luo, Xufeng Wang, Cheng Shen, and Ning Wu
Biogeosciences, 21, 3509–3522, https://doi.org/10.5194/bg-21-3509-2024, https://doi.org/10.5194/bg-21-3509-2024, 2024
Short summary
Short summary
Our study delves into the vital role of subalpine forests in the Qinghai–Tibet Plateau as carbon sinks in the context of climate change. Utilizing advanced eddy covariance systems, we uncover their significant carbon sequestration potential, observing distinct seasonal patterns influenced by temperature, humidity, and radiation. Notably, these forests exhibit robust carbon absorption, with potential implications for global carbon balance.
Colette L. Kelly, Nicole M. Travis, Pascale Anabelle Baya, Claudia Frey, Xin Sun, Bess B. Ward, and Karen L. Casciotti
Biogeosciences, 21, 3215–3238, https://doi.org/10.5194/bg-21-3215-2024, https://doi.org/10.5194/bg-21-3215-2024, 2024
Short summary
Short summary
Nitrous oxide, a potent greenhouse gas, accumulates in regions of the ocean that are low in dissolved oxygen. We used a novel combination of chemical tracers to determine how nitrous oxide is produced in one of these regions, the eastern tropical North Pacific Ocean. Our experiments showed that the two most important sources of nitrous oxide under low-oxygen conditions are denitrification, an anaerobic process, and a novel “hybrid” process performed by ammonia-oxidizing archaea.
Hella van Asperen, Thorsten Warneke, Alessandro Carioca de Araújo, Bruce Forsberg, Sávio José Filgueiras Ferreira, Thomas Röckmann, Carina van der Veen, Sipko Bulthuis, Leonardo Ramos de Oliveira, Thiago de Lima Xavier, Jailson da Mata, Marta de Oliveira Sá, Paulo Ricardo Teixeira, Julie Andrews de França e Silva, Susan Trumbore, and Justus Notholt
Biogeosciences, 21, 3183–3199, https://doi.org/10.5194/bg-21-3183-2024, https://doi.org/10.5194/bg-21-3183-2024, 2024
Short summary
Short summary
Carbon monoxide (CO) is regarded as an important indirect greenhouse gas. Soils can emit and take up CO, but, until now, uncertainty remains as to which process dominates in tropical rainforests. We present the first soil CO flux measurements from a tropical rainforest. Based on our observations, we report that tropical rainforest soils are a net source of CO. In addition, we show that valley streams and inundated areas are likely additional hot spots of CO in the ecosystem.
Yélognissè Agbohessou, Claire Delon, Manuela Grippa, Eric Mougin, Daouda Ngom, Espoir Koudjo Gaglo, Ousmane Ndiaye, Paulo Salgado, and Olivier Roupsard
Biogeosciences, 21, 2811–2837, https://doi.org/10.5194/bg-21-2811-2024, https://doi.org/10.5194/bg-21-2811-2024, 2024
Short summary
Short summary
Emissions of greenhouse gases in the Sahel are not well represented because they are considered weak compared to the rest of the world. However, natural areas in the Sahel emit carbon dioxide and nitrous oxides, which need to be assessed because of extended surfaces. We propose an assessment of such emissions in Sahelian silvopastoral systems and of how they are influenced by environmental characteristics. These results are essential to inform climate change strategies in the region.
Merit van den Berg, Thomas M. Gremmen, Renske J. E. Vroom, Jacobus van Huissteden, Jim Boonman, Corine J. A. van Huissteden, Ype van der Velde, Alfons J. P. Smolders, and Bas P. van de Riet
Biogeosciences, 21, 2669–2690, https://doi.org/10.5194/bg-21-2669-2024, https://doi.org/10.5194/bg-21-2669-2024, 2024
Short summary
Short summary
Drained peatlands emit 3 % of the global greenhouse gas emissions. Paludiculture is a way to reduce CO2 emissions while at the same time generating an income for landowners. The side effect is the potentially high methane emissions. We found very high methane emissions for broadleaf cattail compared with narrowleaf cattail and water fern. The rewetting was, however, effective to stop CO2 emissions for all species. The highest potential to reduce greenhouse gas emissions had narrowleaf cattail.
Antonio Donateo, Daniela Famulari, Donato Giovannelli, Arturo Mariani, Mauro Mazzola, Stefano Decesari, and Gianluca Pappaccogli
EGUsphere, https://doi.org/10.5194/egusphere-2024-1440, https://doi.org/10.5194/egusphere-2024-1440, 2024
Short summary
Short summary
This study focuses on direct measurements of CO2 and CH4 turbulent eddy covariance fluxes in tundra ecosystems in the Svalbard Islands over a two-year period. Our results reveal dynamic interactions between climatic conditions and ecosystem activities such as photosynthesis and microbial activity. The observed net summertime methane uptake is correlated with the activation and aeration of soil microorganisms. High temperature anomalies increase CO2 and CH4 emissions.
Thea H. Heimdal, Galen A. McKinley, Adrienne J. Sutton, Amanda R. Fay, and Lucas Gloege
Biogeosciences, 21, 2159–2176, https://doi.org/10.5194/bg-21-2159-2024, https://doi.org/10.5194/bg-21-2159-2024, 2024
Short summary
Short summary
Measurements of ocean carbon are limited in time and space. Machine learning algorithms are therefore used to reconstruct ocean carbon where observations do not exist. Improving these reconstructions is important in order to accurately estimate how much carbon the ocean absorbs from the atmosphere. In this study, we find that a small addition of observations from the Southern Ocean, obtained by autonomous sampling platforms, could significantly improve the reconstructions.
Guilherme L. Torres Mendonça, Julia Pongratz, and Christian H. Reick
Biogeosciences, 21, 1923–1960, https://doi.org/10.5194/bg-21-1923-2024, https://doi.org/10.5194/bg-21-1923-2024, 2024
Short summary
Short summary
We study the timescale dependence of airborne fraction and underlying feedbacks by a theory of the climate–carbon system. Using simulations we show the predictive power of this theory and find that (1) this fraction generally decreases for increasing timescales and (2) at all timescales the total feedback is negative and the model spread in a single feedback causes the spread in the airborne fraction. Our study indicates that those are properties of the system, independently of the scenario.
François Clayer, Jan Erik Thrane, Kuria Ndungu, Andrew King, Peter Dörsch, and Thomas Rohrlack
Biogeosciences, 21, 1903–1921, https://doi.org/10.5194/bg-21-1903-2024, https://doi.org/10.5194/bg-21-1903-2024, 2024
Short summary
Short summary
Determination of dissolved greenhouse gas (GHG) in freshwater allows us to estimate GHG fluxes. Mercuric chloride (HgCl2) is used to preserve water samples prior to GHG analysis despite its environmental and health impacts and interferences with water chemistry in freshwater. Here, we tested the effects of HgCl2, two substitutes and storage time on GHG in water from two boreal lakes. Preservation with HgCl2 caused overestimation of CO2 concentration with consequences for GHG flux estimation.
Helena Rautakoski, Mika Korkiakoski, Jarmo Mäkelä, Markku Koskinen, Kari Minkkinen, Mika Aurela, Paavo Ojanen, and Annalea Lohila
Biogeosciences, 21, 1867–1886, https://doi.org/10.5194/bg-21-1867-2024, https://doi.org/10.5194/bg-21-1867-2024, 2024
Short summary
Short summary
Current and future nitrous oxide (N2O) emissions are difficult to estimate due to their high variability in space and time. Several years of N2O fluxes from drained boreal peatland forest indicate high importance of summer precipitation, winter temperature, and snow conditions in controlling annual N2O emissions. The results indicate increasing year-to-year variation in N2O emissions in changing climate with more extreme seasonal weather conditions.
Matthias Koschorreck, Norbert Kamjunke, Uta Koedel, Michael Rode, Claudia Schuetze, and Ingeborg Bussmann
Biogeosciences, 21, 1613–1628, https://doi.org/10.5194/bg-21-1613-2024, https://doi.org/10.5194/bg-21-1613-2024, 2024
Short summary
Short summary
We measured the emission of carbon dioxide (CO2) and methane (CH4) from different sites at the river Elbe in Germany over 3 days to find out what is more important for quantification: small-scale spatial variability or diurnal temporal variability. We found that CO2 emissions were very different between day and night, while CH4 emissions were more different between sites. Dried out river sediments contributed to CO2 emissions, while the side areas of the river were important CH4 sources.
Odysseas Sifounakis, Edwin Haas, Klaus Butterbach-Bahl, and Maria P. Papadopoulou
Biogeosciences, 21, 1563–1581, https://doi.org/10.5194/bg-21-1563-2024, https://doi.org/10.5194/bg-21-1563-2024, 2024
Short summary
Short summary
We performed a full assessment of the carbon and nitrogen cycles of a cropland ecosystem. An uncertainty analysis and quantification of all carbon and nitrogen fluxes were deployed. The inventory simulations include greenhouse gas emissions of N2O, NH3 volatilization and NO3 leaching from arable land cultivation in Greece. The inventory also reports changes in soil organic carbon and nitrogen stocks in arable soils.
Sarah M. Ludwig, Luke Schiferl, Jacqueline Hung, Susan M. Natali, and Roisin Commane
Biogeosciences, 21, 1301–1321, https://doi.org/10.5194/bg-21-1301-2024, https://doi.org/10.5194/bg-21-1301-2024, 2024
Short summary
Short summary
Landscapes are often assumed to be homogeneous when using eddy covariance fluxes, which can lead to biases when calculating carbon budgets. In this study we report eddy covariance carbon fluxes from heterogeneous tundra. We used the footprints of each flux observation to unmix the fluxes coming from components of the landscape. We identified and quantified hot spots of carbon emissions in the landscape. Accurately scaling with landscape heterogeneity yielded half as much regional carbon uptake.
Justine Trémeau, Beñat Olascoaga, Leif Backman, Esko Karvinen, Henriikka Vekuri, and Liisa Kulmala
Biogeosciences, 21, 949–972, https://doi.org/10.5194/bg-21-949-2024, https://doi.org/10.5194/bg-21-949-2024, 2024
Short summary
Short summary
We studied urban lawns and meadows in the Helsinki metropolitan area, Finland. We found that meadows are more resistant to drought events but that they do not increase carbon sequestration compared with lawns. Moreover, the transformation from lawns to meadows did not demonstrate any negative climate effects in terms of greenhouse gas emissions. Even though social and economic aspects also steer urban development, these results can guide planning to consider carbon-smart options.
Guantao Chen, Edzo Veldkamp, Muhammad Damris, Bambang Irawan, Aiyen Tjoa, and Marife D. Corre
Biogeosciences, 21, 513–529, https://doi.org/10.5194/bg-21-513-2024, https://doi.org/10.5194/bg-21-513-2024, 2024
Short summary
Short summary
We established an oil palm management experiment in a large-scale oil palm plantation in Jambi, Indonesia. We recorded oil palm fruit yield and measured soil CO2, N2O, and CH4 fluxes. After 4 years of treatment, compared with conventional fertilization with herbicide weeding, reduced fertilization with mechanical weeding did not reduce yield and soil greenhouse gas emissions, which highlights the legacy effects of over a decade of conventional management prior to the start of the experiment.
Elizabeth Gachibu Wangari, Ricky Mwangada Mwanake, Tobias Houska, David Kraus, Gretchen Maria Gettel, Ralf Kiese, Lutz Breuer, and Klaus Butterbach-Bahl
Biogeosciences, 20, 5029–5067, https://doi.org/10.5194/bg-20-5029-2023, https://doi.org/10.5194/bg-20-5029-2023, 2023
Short summary
Short summary
Agricultural landscapes act as sinks or sources of the greenhouse gases (GHGs) CO2, CH4, or N2O. Various physicochemical and biological processes control the fluxes of these GHGs between ecosystems and the atmosphere. Therefore, fluxes depend on environmental conditions such as soil moisture, soil temperature, or soil parameters, which result in large spatial and temporal variations of GHG fluxes. Here, we describe an example of how this variation may be studied and analyzed.
Laurie C. Menviel, Paul Spence, Andrew E. Kiss, Matthew A. Chamberlain, Hakase Hayashida, Matthew H. England, and Darryn Waugh
Biogeosciences, 20, 4413–4431, https://doi.org/10.5194/bg-20-4413-2023, https://doi.org/10.5194/bg-20-4413-2023, 2023
Short summary
Short summary
As the ocean absorbs 25% of the anthropogenic emissions of carbon, it is important to understand the impact of climate change on the flux of carbon between the ocean and the atmosphere. Here, we use a very high-resolution ocean, sea-ice, carbon cycle model to show that the capability of the Southern Ocean to uptake CO2 has decreased over the last 40 years due to a strengthening and poleward shift of the southern hemispheric westerlies. This trend is expected to continue over the coming century.
Petr Znachor, Jiří Nedoma, Vojtech Kolar, and Anna Matoušů
Biogeosciences, 20, 4273–4288, https://doi.org/10.5194/bg-20-4273-2023, https://doi.org/10.5194/bg-20-4273-2023, 2023
Short summary
Short summary
We conducted intensive spatial sampling of the hypertrophic fishpond to better understand the spatial dynamics of methane fluxes and environmental heterogeneity in fishponds. The diffusive fluxes of methane accounted for only a minor fraction of the total fluxes and both varied pronouncedly within the pond and over the studied summer season. This could be explained only by the water depth. Wind substantially affected temperature, oxygen and chlorophyll a distribution in the pond.
Sofie Sjögersten, Martha Ledger, Matthias Siewert, Betsabé de la Barreda-Bautista, Andrew Sowter, David Gee, Giles Foody, and Doreen S. Boyd
Biogeosciences, 20, 4221–4239, https://doi.org/10.5194/bg-20-4221-2023, https://doi.org/10.5194/bg-20-4221-2023, 2023
Short summary
Short summary
Permafrost thaw in Arctic regions is increasing methane emissions, but quantification is difficult given the large and remote areas impacted. We show that UAV data together with satellite data can be used to extrapolate emissions across the wider landscape as well as detect areas at risk of higher emissions. A transition of currently degrading areas to fen type vegetation can increase emission by several orders of magnitude, highlighting the importance of quantifying areas at risk.
Cole G. Brachmann, Tage Vowles, Riikka Rinnan, Mats P. Björkman, Anna Ekberg, and Robert G. Björk
Biogeosciences, 20, 4069–4086, https://doi.org/10.5194/bg-20-4069-2023, https://doi.org/10.5194/bg-20-4069-2023, 2023
Short summary
Short summary
Herbivores change plant communities through grazing, altering the amount of CO2 and plant-specific chemicals (termed VOCs) emitted. We tested this effect by excluding herbivores and studying the CO2 and VOC emissions. Herbivores reduced CO2 emissions from a meadow community and altered VOC composition; however, community type had the strongest effect on the amount of CO2 and VOCs released. Herbivores can mediate greenhouse gas emissions, but the effect is marginal and community dependent.
Ole Lessmann, Jorge Encinas Fernández, Karla Martínez-Cruz, and Frank Peeters
Biogeosciences, 20, 4057–4068, https://doi.org/10.5194/bg-20-4057-2023, https://doi.org/10.5194/bg-20-4057-2023, 2023
Short summary
Short summary
Based on a large dataset of seasonally resolved methane (CH4) pore water concentrations in a reservoir's sediment, we assess the significance of CH4 emissions due to reservoir flushing. In the studied reservoir, CH4 emissions caused by one flushing operation can represent 7 %–14 % of the annual CH4 emissions and depend on the timing of the flushing operation. In reservoirs with high sediment loadings, regular flushing may substantially contribute to the overall CH4 emissions.
Matti Räsänen, Risto Vesala, Petri Rönnholm, Laura Arppe, Petra Manninen, Markus Jylhä, Jouko Rikkinen, Petri Pellikka, and Janne Rinne
Biogeosciences, 20, 4029–4042, https://doi.org/10.5194/bg-20-4029-2023, https://doi.org/10.5194/bg-20-4029-2023, 2023
Short summary
Short summary
Fungus-growing termites recycle large parts of dead plant material in African savannas and are significant sources of greenhouse gases. We measured CO2 and CH4 fluxes from their mounds and surrounding soils in open and closed habitats. The fluxes scale with mound volume. The results show that emissions from mounds of fungus-growing termites are more stable than those from other termites. The soil fluxes around the mound are affected by the termite colonies at up to 2 m distance from the mound.
Tim René de Groot, Anne Margriet Mol, Katherine Mesdag, Pierre Ramond, Rachel Ndhlovu, Julia Catherine Engelmann, Thomas Röckmann, and Helge Niemann
Biogeosciences, 20, 3857–3872, https://doi.org/10.5194/bg-20-3857-2023, https://doi.org/10.5194/bg-20-3857-2023, 2023
Short summary
Short summary
This study investigates methane dynamics in the Wadden Sea. Our measurements revealed distinct variations triggered by seasonality and tidal forcing. The methane budget was higher in warmer seasons but surprisingly high in colder seasons. Methane dynamics were amplified during low tides, flushing the majority of methane into the North Sea or releasing it to the atmosphere. Methanotrophic activity was also elevated during low tide but mitigated only a small fraction of the methane efflux.
Cited articles
Abril, G. and Borges, A. V.: Carbon leaks from flooded land: do we need to
re-plumb the inland water active pipe?, Biogeosciences, 16, 769–784,
https://doi.org/10.5194/bg-16-769-2019, 2019.
Abril, G., Martinez, J.-M., Artigas, L. F., Moreira-Turcq, P., Benedetti,
M. F., Vidal, L., Meziane, T., Kim, J.-H., Bernardes, M. C., Savoye, N.,
Deborde, J., Albéric, P., Souza, M. F. L., Souza, E. L., and Roland, F.:
Amazon river carbon dioxide outgassing fuelled by wetlands, Nature, 505,
395–398, https://doi.org/10.1038/nature12797, 2014.
Abril, G., Bouillon, S., Darchambeau, F., Teodoru, C. R., Marwick, T. R.,
Tamooh, F., Omengo, F. O., 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.
Aho, K. S. and Raymond, P. A.: Differential response of greenhouse gas evasion to storms in forested and wetland streams, J. Geophys. Res., 124, 649–662, https://doi.org/10.1029/2018JG004750, 2019.
Allen, G. H. and Pavelsky, T. M.: Global extent of rivers and streams,
Science, 28, eaat0636, https://doi.org/10.1126/science.aat0636, 2018.
Almeida, R. M., Pacheco, F. S., Barros, N., Rosi, E., and Roland, F.:
Extreme floods increase CO2 outgassing from a large Amazonian river,
Limnol. Oceanogr., 62, 989–999, https://doi.org/10.1002/lno.10480, 2017.
Alsdorf, D., Beighley, E., Laraque, A., Lee, H., Tshimanga, R., O'Loughlin,
F., Mahé, G., Dinga, B., Moukandi, G., and Spencer, R. G. M.:
Opportunities for hydrologic research in the Congo Basin, Rev. Geophys., 54,
378–409, https://doi.org/10.1002/2016RG000517, 2016.
Amaral, J. H. F., Borges, A. V., Melack, J. M., Sarmento, H., Barbosa, P.
M., Kasper, D., Melo, M. L., de Fex Wolf, D., da Silva, J. S., and Forsberg,
B. R.: Influence of plankton metabolism and mixing depth on CO2
dynamics in an Amazon floodplain lake, Sci. Total Environ., 630, 1381–1393,
https://doi.org/10.1016/j.scitotenv.2018.02.331, 2018.
APHA: Standard methods for the examination of water and wastewater, American
Public Health Association, 1325 pp., 1998.
Balagizi, C. M., Darchambeau, F., Bouillon, S., Yalire, M. M., Lambert, T.,
and Borges, A. V.: River geochemistry, chemical weathering and atmospheric
CO2 consumption rates in the Virunga Volcanic Province (East Africa),
Geochem. Geophy. Geosy., 16, 2637–2660, https://doi.org/10.1002/2015GC005999, 2015.
Barbosa, P. M., Melack, J. M., Farjalla, V. F., Amaral, J. H. F., Scofield,
V., and Forsberg, B. R.: Diffusive methane fluxes from Negro, Solimões
and Madeira rivers and fringing lakes in the Amazon basin, Limnol.
Oceanogr., 61, S221–S237, https://doi.org/10.1002/lno.10358, 2016.
Bastviken, D., Ejlertsson, J., and Tranvik, L.: Measurement of methane
oxidation in lakes: A comparison of methods, Environ. Sci. Technol., 36,
3354–3361, https://doi.org/10.1021/es010311p, 2002.
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, p. 50, https://doi.org/10.1126/science.1196808, 2011.
Battin, T. J., Kaplan, L. A., Findlay, S., Hopkinson, C. S., Marti, E.,
Packman, A. I., Newbold, J. D., and Sabater, F.: Biophysical controls on
organic carbon fluxes in fluvial networks, Nat. Geosci., 1, 95–100, https://doi.org/10.1038/ngeo101, 2008.
Baulch, H. M., Schiff, S. L., Maranger, R., and Dillon, P. J.: Nitrogen
enrichment and the emission of nitrous oxide from streams, Global
Biogeochem. Cy., 25, GB4013, https://doi.org/10.1029/2011GB004047, 2011.
Benstead, J. P. and Leigh, D. S.: An expanded role for river networks,
Nat. Geosci., 5, 678–679, https://doi.org/10.1038/ngeo1593, 2012.
Billett, M. F., Palmer, S. M., Hope, D., Deacon, C., Storeton-West, R.,
Hargreaves, K. J., Flechard, C., and Fowler, D.: Linking
land-atmosphere-stream carbon fluxes in a lowland peatland system, Global
Biogeochem. Cy., 18, GB1024, https://doi.org/10.1029/2003GB002058, 2004.
Bird, M. I. and Pousai, P.: Variations of δ13C in the surface
soil organic carbon pool, Global Biogeoch. Cy., 11, 313–322, https://doi.org/10.1029/97GB01197, 1997.
Bird, M. I., Giresse, P., and Chivas, A. R.: Effect of forest and savanna
vegetation on the carbon-isotope composition from the Sanaga River,
Cameroon, Limnol. Oceanogr., 39, 1845–1854, https://doi.org/10.4319/lo.1994.39.8.1845,
1994.
Bowen, G. J., Wassenaar, L. I., and Hobson, K. A.: Global application of stable
hydrogen and oxygen isotopes to wildlife forensics, Oecologia, 143, 337–348,
https://doi.org/10.1007/s00442-004-1813-y, 2005.
Bloom, A. A., Palmer, P. I., Fraser, A., Reay, D. S., and Frankenberg, C.:
Large-scale controls of methanogenesis inferred from methane and gravity
spaceborne data, Science, 327, 322–325, https://doi.org/10.1126/science.1175176, 2010.
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., Darchambeau, F., Lambert, T., Bouillon, S., Morana, C.,
Brouyère, S., Hakoun, V., Jurado, A., Tseng, H.-C., Descy, J.-P.,
and Roland, F. A. E.: Effects of agricultural land use on fluvial carbon
dioxide, methane and nitrous oxide concentrations in a large European river,
the Meuse (Belgium), Sci. Total Environ., 610/611, 342–355, https://doi.org/10.1016/j.scitotenv.2017.08.047, 2018.
Borges, A. V. and Bouillon, S.: Data-base of CO2, CH4, N2O and ancillary data in the Congo River, available at: https://zenodo.org/record/3413449#.XYm2eUYzaUk, last access: 24 September 2019.
Bouillon, S., Abril, G., Borges, A. V., Dehairs, F., Govers, G., Hughes, H.
J., Merckx, R., Meysman, F. J. R., Nyunja, J., Osburn, C., and Middelburg,
J. J.: Distribution, origin and cycling of carbon in the Tana River (Kenya):
a dry season basin-scale survey from headwaters to the delta,
Biogeosciences, 6, 2475–2493, https://doi.org/10.5194/bg-6-2475-2009, 2009.
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, 2012.
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.
Bultot, F.: Atlas Climatique du Bassin Congolais Publications de L'Institut
National pour L'Etude Agronomique du Congo (I.N.E.A.C.), Troisieme Partie,
Temperature et Humidite de L'Air, Rosee, Temperature du Sol, 253 pp., 1972.
Butman, D. and Raymond, P. A.: Significant efflux of carbon dioxide from
streams and rivers in the United States, Nat. Geosci., 4, 839–842, https://doi.org/10.1038/NGEO1294, 2011.
Bwangoy, J.-R. B., Hansen, M. C., Roy, D. P., De Grandi, G., and Justice, C.
O.: Wetland mapping in the Congo Basin using optical and radar remotely
sensed data and derived topographical indices, Remote Sens. Environ., 114,
73–86, https://doi.org/10.1016/j.rse.2009.08.004, 2010.
Canion, A., Overholt, W. A., Kostka, J. E., Huettel, M., Lavik, G., and
Kuypers, M. M. M.: Temperature response of denitrification and anaerobic
ammonium oxidation rates and microbial community structure in Arctic fjord
sediments, Environ. Microbiol., 16, 3331–3344, https://doi.org/10.1111/1462-2920.12593,
2014.
Cardoso, S. J., Enrich-Prast, A., Pace, M. L., and Roland, F.: Do models of
organic carbon mineralization extrapolate to warmer tropical sediments?
Limnol. Oceanogr., 59, 48–54, https://doi.org/10.4319/lo.2014.59.1.0048, 2014.
Ciais, P., Bombelli, A., Williams, M., Piao, S. L., Chave, J., Ryan, C. M.,
Henry, M., Brender, P., and Valentini, R.: The carbon balance of Africa:
synthesis of recent research studies, Philos. T. R. Soc. A, 369,
2038–2057, https://doi.org/10.1098/rsta.2010.0328, 2013.
Coplen, T. B. and Wassenaar, L. I.: LIMS for Lasers 2015 for achieving
long-term accuracy and precision of δ2H, δ17O, and
δ18O of waters using laser absorption spectrometry, Rapid Commun.
Mass Spectr., 29, 2122–2130, https://doi.org/10.1002/rcm.7372,2015.
Cole, B. E. and Cloern, J. E.: An empirical model for estimating
phytoplankton productivity in estuaries, Mar. Ecol. Prog. Ser., 36, 299–305,
https://doi.org/10.3354/meps036299, 1987.
Cole, J. J. and Caraco, N. F.: Carbon in catchments: connecting terrestrial
carbon losses with aquatic metabolism, Mar. Fresh. Res., 52, 101–110, https://doi.org/10.1071/MF00084, 2001.
Cole, J. J., Caraco, N. F., Kling, G. W., and Kratz, T. K.: Carbon dioxide
supersaturation in the surface waters of lakes, Science, 265, 1568–1570,
https://doi.org/10.1126/science.265.5178.1568, 1994.
Cole, J. J., Prairie, Y. T., Caraco, N. F., McDowell, W. H., Tranvik, L. J.,
Striegl, R. G. , Duarte, C. M., Kortelainen, P., Downing, J. A., Middelburg,
J. J., and Melack, J.: Plumbing the global carbon cycle: Integrating inland
waters into the terrestrial carbon budget, Ecosystems, 10, 171–184,
https://doi.org/10.1007/s10021-006-9013-8, 2007.
Coynel, A., Seyler, P., Etcheber, H., Meybeck, M., and Orange, D.: Spatial
and seasonal dynamics of total suspended sediment and organic carbon species
in the Congo River, Global Biogeochem. Cy., 19, GB4019,
https://doi.org/10.1029/2004GB002335, 2005.
Craine J. M., Elmore, A. J., Wang, L., Aranibar, J., Bauters, M., Boeckx,
P., Crowley, B. E., Dawes, M. A., Delzon, S., Fajardo, A., Fang, Y.,
Fujiyoshi, L., Gray, A., Guerrieri, R., Gundale, M. J., Hawke, D.J., Hietz,
P., Jonard, M., Kearsley, E., Kenzo, T., Makarov, M.,
Marañón-Jiménez, S., McGlynn, T. P., McNeil, B. E., Mosher, S.
G., Nelson, D. M., Peri, P. L., Roggy, J. C., Sanders-DeMott, R., Song, M.,
Szpak, P., Templer, P. H., Van der Colff, D., Werner, C., Xu, X., Yang, Y.,
Yu, G., and Zmudczyńska-Skarbek, K.: Isotopic evidence for
oligotrophication of terrestrial ecosystems, Nat. Ecol. Evol., 2, 1735–1744,
https://doi.org/10.1038/s41559-018-0694-0, 2018.
Crawford J. T., Stanley, E. H., Dornblaser, M., and Striegl, R. G.: CO2
time series patterns in contrasting headwater streams of North America,
Aquat. Sci., 79, 473–486, https://doi.org/10.1007/s00027-016-0511-2, 2017.
Dargie, G. C., Lewis, S. L., Lawson, I. T., Mitchard, E. T. A., Page, S. E.,
Bocko, Y. E., and Ifo, S. A.: Age, extent and carbon storage of the central
Congo Basin peatland complex, Nature, 542, 86–90, https://doi.org/10.1038/nature21048, 2017.
Deirmendjian, L. and Abril, G.: Carbon dioxide degassing at the
groundwater-stream-atmosphere interface: isotopic equilibration and
hydrological mass balance in a sandy watershed, J. Hydrol., 558, 129–143,
2018.
Deirmendjian, L., Loustau, D., Augusto, L., Lafont, S., Chipeaux, C.,
Poirier, D., and Abril, G.: Hydro-ecological controls on dissolved carbon
dynamics in groundwater and export to streams in a temperate pine forest,
Biogeosciences, 15, 669–691, https://doi.org/10.5194/bg-15-669-2018, 2018.
Dinsmore, K. J., Wallin, M. B., Johnson, M. S., Billett, M. F., Bishop, K.,
Pumpanen, J., and Ojala, A.: Contrasting CO2 concentration discharge
dynamics in headwater streams: a multi-catchment comparison, J. Geophys.
Res., 118, 445–461, https://doi.org/10.1002/jgrg.20047, 2013.
Del Giorgio, P. A., Cole, J. J., Caraco, N. F., and Peters, R. H.: Linking
planktonic biomass and metabolism to net gas fluxes in northern temperate
lakes, Ecology, 80, 1422–1431, https://doi.org/10.1890/0012-9658(1999)080[1422:LPBAMT]2.0.CO;2, 1999.
Descy, J.-P., Hardy, M.-A., Sténuite, S., Pirlot, S., Leporcq, B.,
Kimirei, I., Sekadende, B., Mwaitega, S. R., and Sinyenza, D.: Phytoplankton
pigments and community composition in Lake Tanganyika, Freshwater Biol.,
50, 668–684, https://doi.org/10.1111/j.1365-2427.2005.01358.x, 2005.
Descy, J.-P., Darchambeau, F., Lambert, T., Stoyneva, M. P., Bouillon, S.,
and Borges, A. V.: Phytoplankton dynamics in the Congo River, Freshwater Biol.,
62, 87–101, https://doi.org/10.1111/fwb.12851, 2017.
Doctor, D. H., Kendall, C., Sebestyen, S. D., Shanley, J. B., Ohte, N., and
Boyer, E. W.: Carbon isotope fractionation of dissolved inorganic carbon
(DIC) due to outgassing of carbon dioxide from a headwater stream, Hydrol.
Process., 22, 2410–2423, https://doi.org/10.1002/hyp.6833, 2008.
Downing, J. A., Cole, J. J., Duarte, C. M., Middelburg, J. J., Melack, J.
M., Prairie, Y. T., Kortelainen, P., Striegl, R. G., McDowell, W. H., and
Tranvik, L. J.: Global abundance and size distribution of streams and
rivers, Inland Waters, 2, 229–236, https://doi.org/10.5268/IW-2.4.502, 2012.
Duvert, C., Butman, D. E., Marx, A., Ribolzi, O., and Hutley, L. B.: CO2
evasion along streams driven by groundwater inputs and geomorphic controls,
Nat. Geosci., 11, 813–818, https://doi.org/10.1038/s41561-018-0245-y, 2018.
Fisher, J. B., Sikka, M., Sitch, S., Ciais, P., Poulter, B., Galbraith, D.,
Lee, J.-E., Huntingford, C., Viovy, N., Zeng, N., Ahlström, A., Lomas,
M. R., Levy, P. E., Frankenberg, C., Saatchi, S., and Malhi, Y.: African
tropical rainforest net carbon dioxide fluxes in the twentieth century,
Philos. T. R. Soc. B, 368, 20120376, https://doi.org/10.1098/rstb.2012.0376, 2013.
Fluet-Chouinard, E., Lehner, B., Rebelo, L.-M., Papa, F., and Hamilton,
S. K.: Development of a global inundation map at high spatial resolution from
topographic downscaling of coarse-scale remote sensing data, Remote Sens.
Environ., 158, 348–361, https://doi.org/10.1016/j.rse.2014.10.015, 2015.
Frankignoulle, M., Borges, A., and Biondo R.: A new design of equilibrator
to monitor carbon dioxide in highly dynamic and turbid environments, Water
Res., 35, 1344–1347, https://doi.org/10.1016/S0043-1354(00)00369-9, 2001.
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.
Gillikin, D. P. and Bouillon, S.: Determination of δ18O of
water and δ13C of dissolved inorganic carbon using a simple
modification of an elemental analyzer – isotope ratio mass spectrometer
(EA-IRMS): an evaluation, Rapid Commun. Mass Spectr., 21, 1475–1478, https://doi.org/10.1002/rcm.2968, 2007.
Gran, G.: Determination of the equivalence point in potentiometric
titrations Part II, The Analyst, 77, 661–671, https://doi.org/10.1039/AN9527700661,
1952.
Hamilton, S. K., Sippel, S. J., and Melack J. M.: Comparison of inundation
patterns among major South American floodplains, J. Geophys. Res., 107, LBA
5-1-LBA 5-14, https://doi.org/10.1029/2000JD000306, 2002.
Happell, J., Chanton, J. P., and Showers, W.: The influence of methane
oxidation on the stable isotopic composition of methane emitted from Florida
Swamp forests, Geochim. Cosmochim. Ac., 58, 4377–4388,
https://doi.org/10.1016/0016-7037(94)90341-7, 1994.
Hedges, J. I., Clark, W. A., Quay, P. D., Richey, J. E., Devol, A. H., and
de M. Santos, U.: Compositions and fluxes of particulate organic material in
the Amazon River, Limnol Oceanogr., 31, 717–738, https://doi.org/10.4319/lo.1986.31.4.0717, 1986.
Hotchkiss, E. R., Hall Jr, R. O., Sponseller, R. A., Butman, D., Klaminder,
J., Laudon, H., Rosvall, M., and Karlsson, J.: Sources of and processes
controlling CO2 emissions change with the size of streams and rivers, Nat.
Geosci., 8, 696–699, https://doi.org/10.1038/ngeo2507, 2015.
Hu, M., Chen, D., and Dahlgren, R. A.: Modeling nitrous oxide emission from
rivers: a global Assessment, Glob. Change Biol., 22, 3566–3582, https://doi.org/10.1111/gcb.13351, 2016.
Hughes, R. H. and Hughes, J. S.: A directory of African wetlands, IUCN,
ISBN 2-88032-949-3, 820 pp., 1992.
Huotari, J., Haapanala, S., Pumpanen, J., Vesala, T., and Ojala, A.:
Efficient gas exchange between a boreal river and the atmosphere, Geophys.
Res. Lett., 40, 5683–5686, https://doi.org/10.1002/2013GL057705, 2013.
Kindler, R., Siemens, J., Kaiser, K., Walmsley, D. C., Bernhofer, C.,
Buchmann, N., Cellier, P., Eugster, W., Gleixner, G., Grunwald, T., Heim,
A., Ibrom, A., Jones, S. K., Jones, M., Klumpp, K., Kutsch, W., Steenberg
Larsen, K., Lehuger, S., Loubet, B., McKenzie, R., Moors, E., Osborne, B.,
Pilegaard, K., Rebmann, C., Saunders, M., Schmidt, M. W. I., Schrumpf, M.,
Seyfferth, J., Skiba, U., Soussana, J.-F., Sutton, M. A.; Tefs, C.,
Vowinckel, B., Zeeman, M. J., and Kaupenjohann, M.: Dissolved carbon
leaching from soil is a crucial component of net ecosystem carbon balance,
Glob. Change Biol., 17, 1167–1185, https://doi.org/10.1111/j.1365-2486.2010.02282.x,
2011.
Klaus, M., Geibrink, E., Jonsson, A., Bergström, A.-K., Bastviken, D.,
Laudon, H., Klaminder, J., and Karlsson, J.: Greenhouse gas emissions from
boreal inland waters unchanged after forest harvesting, Biogeosciences, 15,
5575–5594, https://doi.org/10.5194/bg-15-5575-2018, 2018.
Kokic, J., Sahlée, E., Sobek, S., Vachon, D., and Wallin, M. B.: High
spatial variability of gas transfer velocity in streams revealed by
turbulence measurements, Inland Waters, 8, 461–473, https://doi.org/10.1080/20442041.2018.1500228,
2018.
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.
Kosten, S., Piñeiro, M., de Goede, E., de Klein, J., Lamers, L. P. M., and
Ettwig, K.: Fate of methane in aquatic systems dominated by free-floating
plants, Water Res., 104, 200–207, 2016.
Kroeze, C., Dumont, E., and Seitzinger, S. P.: Future trends in emissions of
N2O from rivers and estuaries, J. Integr. Environ. Sc., 7, 71–78, https://doi.org/10.1080/1943815X.2010.496789, 2010.
Lambert, T., Bouillon, S., Darchambeau, F., Massicotte, P., and Borges,
A.V.: Shift in the chemical composition of dissolved organic matter in the
Congo River network, Biogeosciences, 13, 5405–5420,
https://doi.org/10.5194/bg-13-5405-2016, 2016.
Laraque, A., Mietton, M. Olivry, J. C., and Pandi, A.: Impact of lithological
and vegetal covers on flow discharge and water quality of Congolese
tributaries from the Congo river, Rev. Sci. Eau., 11, 209–224,
1998.
Laraque, A., Bricquet, J. P., Pandi, A., and Olivry, J. C.: A review of
material transport by the Congo River and its tributaries, Hydrol. Process.,
23, 3216–3224, https://doi.org/10.1002/hyp.7395, 2009.
Lauerwald, R., Laruelle, G. G., Hartmann, J., Ciais, P., and Regnier, P. A.
G.: Spatial patterns in CO2 evasion from the global river network,
Global Biogeochem. Cy., 29, 534–554, https://doi.org/10.1002/2014GB004941, 2015.
Lauerwald, R., Regnier, P., Camino-Serrano, M., Guenet, B., Guimberteau, M.,
Ducharne, A., Polcher, J., and Ciais, P.: ORCHILEAK (revision 3875): a new
model branch to simulate carbon transfers along the terrestrial–aquatic
continuum of the Amazon basin, Geosci. Model Dev., 10, 3821–3859,
https://doi.org/10.5194/gmd-10-3821-2017, 2017.
Le, T. T. H., Fettig, J., and Meon, G.: Kinetics and simulation of
nitrification at various pH values of a polluted river in the tropics,
Ecohydrol. Hydrobiol., 19, 54–65, 2019.
Liptay, K., Chanton, J., Czepiel, P., and Mosher, B.: Use of stable isotopes
to determine methane oxidation in landfill cover soils, J. Geophys. Res.,
103, 8243–8250, https://doi.org/10.1029/97JD02630, 1998.
Liss, P. S. and Slater, P. G.: Flux of gases across the air sea interface,
Nature, 247, 181–184, https://doi.org/10.1038/247181a0, 1974.
Liu, S. and Raymond, P. A.: Hydrologic controls on pCO2 and CO2
efflux in US streams and rivers, Limnol. Oceanogr. Lett., 3, 428–435, https://doi.org/10.1002/lol2.10095, 2018.
Lynch, J. K., Beatty, C. M., Seidel, M. P., Jungst, L. J., and DeGrandpre, M.
D.: Controls of riverine CO2 over an annual cycle determined using
direct, high temporal resolution pCO2 measurements, J. Geophys. Res.,
115, G03016, https://doi.org/10.1029/2009JG001132, 2010.
Maavara, T., Lauerwald, R., Laruelle, G.G., Akbarzadeh, Z., Bouskill, N. J.,
Van Cappellen, P., and Regnier, P.: Nitrous oxide emissions from inland
waters: Are IPCC estimates too high?, Glob. Change Biol., 25, 473–488, https://doi.org/10.1111/gcb.14504,
2018.
Malhi, Y., Adu-Bredu, S., Asare, R. A., Lewis, S. L., and Mayaux, P.:
African rainforests: past, present and future, Philos. T. R. Soc. B, 368,
20120312, https://doi.org/10.1098/rstb.2012.0312, 2013.
Mann, P. J., Spencer, R. G. M., Dinga, B. J., Poulsen, J. R., Hernes, P. J.,
Fiske, G., Salter, M. E., Wang, Z. A., Hoering, K. A., Six, J., and Holmes
R. M.: The biogeochemistry of carbon across a gradient of streams and rivers
within the Congo Basin, J. Geophys. Res.-Biogeo., 119, 687–702,
https://doi.org/10.1002/2013JG002442, 2014.
Maurice, L., Rawlins, B. G., Farr, G., Bell, R., and Gooddy, D. C.: The
influence of flow and bed slope on gas transfer in steep streams and their
implications for evasion of CO2, J. Geophys. Res.-Biogeo., 122,
2862–2875, https://doi.org/10.1002/2017JG004045, 2017.
Marwick, T. R., Tamooh, F., Ogwoka, B., Teodoru, C., Borges, A. V.,
Darchambeau, F., and Bouillon, S.: Dynamic seasonal nitrogen cycling in
response to anthropogenic N loading in a tropical catchment,
Athi–Galana–Sabaki River, Kenya, Biogeosciences, 11, 1–18,
https://doi.org/10.5194/bg-11-1-2014, 2014.
Marx, A., Dusek, J., Jankovec, J., Sanda, M., Vogel, T., van Geldern, R.,
Hartmann, J., and Barth, J. A. C.: A review of CO2 and associated
carbon dynamics in headwater streams: A global perspective, Rev. Geophys.,
55, 560–585, https://doi.org/10.1002/2016RG000547, 2017.
McDowell, M. J. and Johnson, M. S.: Gas transfer velocities evaluated using
carbon dioxide as a tracer show high streamflow to be a major driver of
total CO2 evasion flux for a headwater stream, J. Geophys. Res.-Biogeo., 123, 2183–2197, https://doi.org/10.1029/2018JG004388, 2018.
Melack, J. M., Hess, L. L., Gastil, M., Forsberg, B. R., Hamilton, S. K.,
Lima, I. B. T., and Novo, E. M. L. M.: Regionalization of methane emissions in
the Amazon Basin with microwave remote sensing, Glob. Change Biol., 10,
530–544, https://doi.org/10.1111/j.1365-2486.2004.00763.x, 2004.
Meybeck, M.: Global chemical weathering of surficial rocks estimated from
river dissolved loads, Am. J. Sci., 287, 401–428, https://doi.org/10.2475/ajs.287.5.401,
1987.
Millero, F. J.: The thermodynamics of the carbonate system in seawater,
Geochem. Cosmochem. Ac., 43, 1651–1661, https://doi.org/10.1016/0016-7037(79)90184-4,1979.
Morana, C., Borges, A. V., Roland, F. A. E., Darchambeau, F., Descy, J.-P.,
and Bouillon, S.: Methanotrophy within the water column of a large
meromictic, tropical lake (Lake Kivu, East Africa), Biogeosciences, 12,
2077–2088, https://doi.org/10.5194/bg-12-2077-2015, 2015.
Nkounkou, R. R. and Probst, J. L.: Hydrology and geochemistry of the Congo
river system, Mitt. Geol–Palaont. Inst. Univ. Hamburg, SCOPE/UNEP, 64,
483–508, 1987.
O'Loughlin, F., Trigg, M. A., Schumann, G. J.-P., and Bates, P. D.:
Hydraulic characterization of the middle reach of the Congo River, Water
Resour. Res., 49, 5059–5070, https://doi.org/10.1002/wrcr.20398, 2013.
Peter, H., Singer, G. A., Preiler, C., Chifflard, P., Steniczka, G., and Battin,
T. J.: Scales and drivers of temporal pCO2 dynamics in an Alpine
stream, J. Geophys. Res.-Biogeo., 119, 1078–1091,
https://doi.org/10.1002/2013JG002552, 2014.
Powell, R. L., Yoo, E.-H., and Still, C. J.: Vegetation and soil carbon-13
isoscapes for South America: integrating remote sensing and ecosystem
isotope measurements, Ecosphere, 3, 1–25, https://doi.org/10.1890/ES12-00162.1, 2012.
Prairie, Y. T., Bird, D. F., and Cole, J. J.: The summer metabolic balance in
the epilimnion of southeastern Quebec lakes, Limnol. Oceanogr., 47, 316–321,
https://doi.org/10.4319/lo.2002.47.1.0316, 2002.
Raymond, P. A., Zappa, C. J., Butman, D., Bott, T. L., Potter, C.,
Mulholland, P., Laursen, A. E., McDowell, W. H., and Newbold, D.: Scaling
the gas transfer velocity and hydraulic geometry in streams and small
rivers, Limnol. Oceanogr. Fluids Environ., 2, 41–53, https://doi.org/10.1215/21573689-1597669, 2012.
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.
Reiman, J. H. and Xu, J. Y.: Diel variability of pCO2 and CO2
outgassing from the Lower Mississippi River: Implications for riverine
CO2 outgassing estimation, Water, 11, 1–15, https://doi.org/10.3390/w11010043,
2019.
Richardson, D. C., Newbold, J. D., Aufdenkampe, A. K., Taylor, P. G., and
Kaplan, L. A.: Measuring heterotrophic respiration rates of suspended
particulate organic carbon from stream ecosystems, Limnol. Oceanogr.-Method., 11, 247–261, https://doi.org/10.4319/lom.2013.11.247, 2013.
Richey, J. E., Devol, A. H., Wofy, S. C., Victoria, R., and Riberio, M. N.
G.: Biogenic gases and the oxidation and reduction of carbon in Amazon River
and floodplain waters, Limnol. Oceanogr., 33, 551–561,
https://doi.org/10.4319/lo.1988.33.4.0551, 1988.
Richey, J. E., Melack, J. M., Aufdenkampe, A. K., Ballester, V. M., and Hess,
L.: Outgassing from Amazonian rivers and wetlands as a large tropical source
of atmospheric CO2, Nature, 416, 617–620, https://doi.org/10.1038/416617a, 2002.
Runge, J.: Large Rivers: Geomorpholgy and Management, edited by: Gupta, A.,
John Wiley & Sons., 293–309, 2008.
Santos, I. R., Maher, D. T., and, Eyre B. D.: Coupling automated radon and
carbon dioxide measurements in coastal waters, Environ. Sci. Technol., 46,
7685–7691, https://doi.org/10.1021/es301961b, 2012.
Sawakuchi, H. O., Bastviken, D., Sawakuchi, A. O., Krusche, A. V.,
Ballester, M. V. R., and Richey, J. E.: Methane emissions from Amazonian
Rivers and their contribution to the global methane budget, Glob. Change
Biol., 20, 2829–2840, https://doi.org/10.1111/gcb.12646, 2014.
Sawakuchi, H. O., Bastviken, D., Sawakuchi, A. O., Ward, N. D., Borges, C. D.,
Tsai, S. M., Richey, J. E., Ballester, M. V. R. and Krusche, A. V.: Oxidative
mitigation of aquatic methane emissions in large Amazonian rivers, Glob.
Change Biol., 22, 1075–1085, https://doi.org/10.1111/gcb.13169, 2016.
Scofield, V., Melack, J. M., Barbosa, P. M., Amaral, J. H. F., Forsberg, B.
R., and Farjalla, V. F.: Carbon dioxide outgassing from Amazonian aquatic
ecosystems in the Negro River basin, Biogeochemistry, 129, 77–91, https://doi.org/10.1007/s10533-016-0220-x, 2016.
Seitzinger, S. P. and Kroeze, C.: Global distribution of nitrous oxide
production and N inputs in freshwater and coastal marine ecosystems, Global
Biogeochem. Cy., 12, 93–113, https://doi.org/10.1029/97GB03657, 1998.
Simpson, H. and Herczeg, A.: Stable isotopes as an indicator of evaporation
in the River Murray, Australia, Water Resour. Res., 27, 1925–1935,
https://doi.org/10.1029/91WR00941, 1991.
Spencer, R. G. M., Hernes, P. J., Aufdenkampe, A. K., Baker, A., Gulliver,
P., Stubbins, A., Aiken, G. R., Dyda, R. Y., Butler, K. D., Mwamba, V. L.,
Mangangu, A. M., Wabakanghanzi, J. N., and Six, J.: An initial investigation
into the organic matter biogeochemistry of the Congo River, Geochim.
Cosmochim. Ac., 84, 614–627, https://doi.org/10.1016/j.gca.2012.01.013, 2012.
SCA (Standing committee of Analysts): Ammonia in waters. Methods for the
examination of waters and associated materials, 16 pp., 1981.
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.
Still, C. J. and Powell, R. L.: Continental-scale distributions of
vegetation stable carbon isotope ratios, edited by: West, J. B., Bowen, G. J., Dawson, T. E., Tu,
K. P., Isoscapes, the Netherlands, Springer Netherlands, 179–193, 2010.
Takahashi, T., Sutherland, S. C., Wanninkhof, R., Sweeney, C., Feely, R. A.,
Chipman, D. W., Hales, B., Friederich, G., Chavez, F., Sabine, C., Watson,
A., Bakker, D. C. E., Schuster, U., Metzl, N., Yoshikawa-Inoue, H.I., Ishii,
M., Midorikawa, T., Nojiri, Y., Körtzinger, A., Steinhoff, T., Hoppema,
M., Olafsson, J., Arnarson, T. S., Tilbrook, B., Johannessen, T., Olsen, A.,
Bellerby, R., Wong, C. S., Delille, B., Bates, N. R., and de Baar, H. J. W.:
Climatological mean and decadal change in surface ocean pCO2, and net
sea-air CO2 flux over the global oceans, Deep-Sea Res. Pt. II, 56, 554–577,
https://doi.org/10.1016/j.dsr2.2008.12.009, 2009.
Tamooh, F., Borges, A. V., Meysman, F. J. R., Van Den Meersche, K., Dehairs,
F., Merckx, R., and Bouillon, S.:Dynamics of dissolved inorganic carbon and
aquatic metabolism in the Tana River basin, Kenya, Biogeosciences, 10,
6911–6928, https://doi.org/10.5194/bg-10-6911-2013, 2013
Teodoru, C. R., Nyoni, F. C., Borges, A. V., Darachambeau, F., Nyambe, I.,
and Bouillon, S.: Spatial variability and temporal dynamics of greenhouse
gas (CO2, CH4, N2O) concentrations and fluxes along the
Zambezi River mainstem and major tributaries, Biogeosciences, 12, 2431–2453,
https://doi.org/10.5194/bg-12-2431-2015, 2015.
Tyler, S. C., Bilek, R. S., Sass, R. L., and Fisher, F. M.: Methane oxidation
and pathways of production in a Texas paddy field deduced from measurements
of flux, δ13C, and δD of CH4, Global Biogeochem.
Cy., 11, 323–348, https://doi.org/10.1029/97GB01624, 1997.
Ulseth, A. J., Hall Jr, R. O., Canadell, M. B., Madinger, H. L., Niayifar,
A., and Battin, T. J.: Distinct air–water gas exchange regimes in low- and
high-energy streams, Nat. Geosci., 12, 259–263, https://doi.org/10.1038/s41561-019-0324-8, 2019
Upstill-Goddard, R. C., Salter, M. E., Mann, P. J., Barnes, J., Poulsen, J.,
Dinga, B., Fiske, G. J., and Holmes, R. M.: The riverine source of CH4
and N2O from the Republic of Congo, western Congo Basin,
Biogeosciences, 14, 2267–2281, https://doi.org/10.5194/bg-14-2267-2017, 2017.
Ward, N. D., Krusche, A. V., Sawakuchi, H. O., Brito, D. C., Cunha, A. C.,
Sousa Moura, J. M., da Silva, R., Yager, P. L., Keil, R. G., and Richey, J.
E.: The compositional evolution of dissolved and particulate organic matter
along the lower Amazon River–Óbidos to the ocean, Mar. Chem., 177,
244–256, https://doi.org/10.1016/j.marchem.2015.06.013, 2015.
Ward N. D., Sawakuchi, H. O., Neu, V., Less, D. F. S., Valerio, A. M., Cunha, A. C., Kampel, M., Bianchi, T. S., Krusche, A. V., Richey, J. E., and Keil, R.
G.: Velocity-amplified microbial respiration rates in the lower Amazon
River, Limnol. Oceanogr. Lett., 3, 265–274, https://doi.org/10.1002/lol2.10062,
2018.
Wassenaar, L. I., Coplen, T. B., and Aggarwal, P. K.: Approaches for
achieving long-term accuracy and precision of δ18O and δ2H for waters analyzed using laser absorption spectrometers, Environ.
Sci. Technol., 48, 1123–1131, https://doi.org/10.1021/es403354n, 2014.
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, https://doi.org/10.1016/0304-4203(80)90024-9, 1980.
Wissmar, R. C., Richey, J. E., Stallard, R. F., and Edmond, J. M.: Plankton
metabolism and carbon processes in the Amazon river, its tributaries, and
floodplain waters, Peru-Brazil, May–June 1977, Ecology, 62, 1622–1633, https://doi.org/10.2307/1941517, 1981.
Yoshida, N., Iguchi, H., Yurimoto, H., Murakami, A., and Sakai, Y.: Aquatic
plant surface as a niche for methanotrophs, Front. Microbiol., 30, 1–9,
https://doi.org/10.3389/fmicb.2014.00030, 2014.
Zhou, L., Tian, Y., Myneni, R. B., Ciais, P., Saatchi, S. L., Yi Y.,
Shilong, P., Chen, H., Vermote, E. F., Song, C., and Hwang, T.: Widespread
decline of Congo rainforest greenness in the past decade, Nature, 509,
86–90, https://doi.org/10.1038/nature13265, 2014.
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.
Tropical rivers might be strong sources of CO2 and CH4 to the atmosphere, although there is an...
Altmetrics
Final-revised paper
Preprint