Articles | Volume 18, issue 4
https://doi.org/10.5194/bg-18-1417-2021
© Author(s) 2021. 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-18-1417-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
24 Feb 2021
Research article |
| 24 Feb 2021
| 24 Feb 2021
Spatio-temporal variations in lateral and atmospheric carbon fluxes from the Danube Delta
Marie-Sophie Maier
CORRESPONDING AUTHOR
Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zurich 8092, Switzerland
Eawag, Swiss Federal Institute of Aquatic Science and Technology,
Kastanienbaum 6047, Switzerland
Cristian R. Teodoru
Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zurich 8092, Switzerland
Bernhard Wehrli
Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zurich 8092, Switzerland
Eawag, Swiss Federal Institute of Aquatic Science and Technology,
Kastanienbaum 6047, Switzerland
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R. Scott Winton, Silvia López-Casas, Daniel Valencia-Rodríguez, Camilo Bernal-Forero, Juliana Delgado, Bernhard Wehrli, and Luz Jiménez-Segura
Hydrol. Earth Syst. Sci., 27, 1493–1505, https://doi.org/10.5194/hess-27-1493-2023, https://doi.org/10.5194/hess-27-1493-2023, 2023
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Dams are an important and rapidly growing means of energy generation in the Tropical Andes of South America. To assess the impacts of dams in the region, we assessed differences in the upstream and downstream water quality of all hydropower dams in Colombia. We found evidence of substantial dam-induced changes in water temperature, dissolved oxygen concentration and suspended sediments. Dam-induced changes in Colombian waters violate regulations and are likely impacting aquatic life.
Anna Canning, Bernhard Wehrli, and Arne Körtzinger
Biogeosciences, 18, 3961–3979, https://doi.org/10.5194/bg-18-3961-2021, https://doi.org/10.5194/bg-18-3961-2021, 2021
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Inland waters are usually not well restrained in terms of greenhouse gas measurements. One of these regions is the Danube Delta, Romania. Therefore, we measured continuously with sensors to collect high-resolution data for CH4 and O2 throughout the Delta. We found significant variation for all concentrations over the day and night and between regions, as well as large spatial variation throughout all regions, with large CH4 concentrations flowing in from the reed beds to the lakes.
Sigrid van Grinsven, Kirsten Oswald, Bernhard Wehrli, Corinne Jegge, Jakob Zopfi, Moritz F. Lehmann, and Carsten J. Schubert
Biogeosciences, 18, 3087–3101, https://doi.org/10.5194/bg-18-3087-2021, https://doi.org/10.5194/bg-18-3087-2021, 2021
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Lake Lovojärvi is a nutrient-rich lake with high amounts of methane at the bottom, but little near the top. Methane comes from the sediment and rises up through the water but is consumed by microorganisms along the way. They use oxygen if available, but in deeper water layers, no oxygen was present. There, nitrite, iron and humic substances were used, besides a collaboration between photosynthetic organisms and methane consumers, in which the first produced oxygen for the latter.
Magdalena J. Mayr, Matthias Zimmermann, Jason Dey, Bernhard Wehrli, and Helmut Bürgmann
Biogeosciences, 17, 4247–4259, https://doi.org/10.5194/bg-17-4247-2020, https://doi.org/10.5194/bg-17-4247-2020, 2020
Benedikt Ehrenfels, Maciej Bartosiewicz, Athanasio S. Mbonde, Kathrin B. L. Baumann, Christian Dinkel, Julian Junker, Tumaini Kamulali, Ismael A. Kimirei, Daniel Odermatt, Francesco Pomati, Emmanuel A. Sweke, and Bernhard Wehrli
Biogeosciences Discuss., https://doi.org/10.5194/bg-2020-214, https://doi.org/10.5194/bg-2020-214, 2020
Revised manuscript not accepted
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Cyanobacterial blooms are a widespread phenomenon, but their formation is poorly understood in nutrient-poor water bodies. During two cruises we collected physical, nutrient, pigment and phytoplankton data to study nitrogen fixing cyanobacteria (diazotrophs) in Lake Tanganyika, Africa. We found that, due to their capability of fixing gaseous nitrogen, diazotrophs thrive when the supply of dissolved inorganic nitrogen to the sun-lit surface waters is low, but phosphorous is still available.
Alberto V. Borges, François Darchambeau, Thibault Lambert, Cédric Morana, George H. Allen, Ernest Tambwe, Alfred Toengaho Sembaito, Taylor Mambo, José Nlandu Wabakhangazi, Jean-Pierre Descy, Cristian R. Teodoru, and Steven Bouillon
Biogeosciences, 16, 3801–3834, https://doi.org/10.5194/bg-16-3801-2019, https://doi.org/10.5194/bg-16-3801-2019, 2019
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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.
Robert Scott Winton, Elisa Calamita, and Bernhard Wehrli
Biogeosciences, 16, 1657–1671, https://doi.org/10.5194/bg-16-1657-2019, https://doi.org/10.5194/bg-16-1657-2019, 2019
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A global boom in dam construction throughout the world’s tropics motivated us to review and synthesize information on the water quality impacts of dams with a focus on low-latitude contexts and scope for mitigation. Sediment trapping and reservoir stratification are key process driving chemical and ecological impacts on tropical rivers. We analyze the 54 most-voluminous low-latitude reservoirs and find that stratification seems to be a ubiquitous phenomenon.
Thomas Steinsberger, Martin Schmid, Alfred Wüest, Robert Schwefel, Bernhard Wehrli, and Beat Müller
Biogeosciences, 14, 3275–3285, https://doi.org/10.5194/bg-14-3275-2017, https://doi.org/10.5194/bg-14-3275-2017, 2017
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Based on a broad dataset of lake sediment analysis and porewater measurements from various Swiss lakes, this paper argues that the accumulation of organic carbon in the sediment is one of the main driving forces for the generation of reduced substances such as methane and ammonia. These substances significantly contribute to the hypolimnetic oxygen consumption. The relationships presented help to evaluate the scale of the flux of reduced substances where no direct measurements are available.
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
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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. 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
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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.
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
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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.
J. Friedrich, F. Janssen, D. Aleynik, H. W. Bange, N. Boltacheva, M. N. Çagatay, A. W. Dale, G. Etiope, Z. Erdem, M. Geraga, A. Gilli, M. T. Gomoiu, P. O. J. Hall, D. Hansson, Y. He, M. Holtappels, M. K. Kirf, M. Kononets, S. Konovalov, A. Lichtschlag, D. M. Livingstone, G. Marinaro, S. Mazlumyan, S. Naeher, R. P. North, G. Papatheodorou, O. Pfannkuche, R. Prien, G. Rehder, C. J. Schubert, T. Soltwedel, S. Sommer, H. Stahl, E. V. Stanev, A. Teaca, A. Tengberg, C. Waldmann, B. Wehrli, and F. Wenzhöfer
Biogeosciences, 11, 1215–1259, https://doi.org/10.5194/bg-11-1215-2014, https://doi.org/10.5194/bg-11-1215-2014, 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
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Total alkalinity (TA) is the oceanic capacity to store CO2. Estuaries can be a TA source. Anaerobic metabolic pathways like denitrification (reduction of NO3− to N2) generate TA and are a major nitrogen (N) sink. Another important N sink is anammox that transforms NH4+ with NO2− into N2 without TA generation. By combining TA and N2 production, we identified a TA source, denitrification, occurring in the water column and suggest anammox as the dominant N2 producer in the bottom layer of the Ems.
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The direction and magnitude of the net erosion-induced land–atmosphere C exchange have been the topic of a big scientific debate for more than a decade now. Many have assumed that erosion leads to a loss of soil carbon to the atmosphere, whereas others have shown that erosion ultimately leads to a carbon sink. Here, we show that the soil carbon erosion source–sink paradox is reconciled when the broad range of temporal and spatial scales at which the underlying processes operate are considered.
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Biogeosciences, 20, 663–686, https://doi.org/10.5194/bg-20-663-2023, https://doi.org/10.5194/bg-20-663-2023, 2023
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Terrestrial organic matter (TerrOM) is transported to the ocean by rivers, where its burial can potentially form a long-term carbon sink. This burial is dependent on the type and characteristics of the TerrOM. We used bulk sediment properties, biomarkers, and palynology to identify the dispersal patterns of plant-derived, soil–microbial, and marine OM in the northern Gulf of Mexico and show that plant-derived OM is transported further into the coastal zone than soil and marine-produced TerrOM.
Paul A. Bukaveckas
Biogeosciences, 19, 4209–4226, https://doi.org/10.5194/bg-19-4209-2022, https://doi.org/10.5194/bg-19-4209-2022, 2022
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Inland waters play an important role in the global carbon cycle by storing, transforming and transporting carbon from land to sea. Comparatively little is known about carbon dynamics at the river–estuarine transition. A study of tributaries of Chesapeake Bay showed that biological processes exerted a strong effect on carbon transformations. Peak carbon retention occurred during periods of elevated river discharge and was associated with trapping of particulate matter.
Frédérique M. S. A. Kirkels, Huub M. Zwart, Muhammed O. Usman, Suning Hou, Camilo Ponton, Liviu Giosan, Timothy I. Eglinton, and Francien Peterse
Biogeosciences, 19, 3979–4010, https://doi.org/10.5194/bg-19-3979-2022, https://doi.org/10.5194/bg-19-3979-2022, 2022
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Soil organic carbon (SOC) that is transferred to the ocean by rivers forms a long-term sink of atmospheric CO2 upon burial on the ocean floor. We here test if certain bacterial membrane lipids can be used to trace SOC through the monsoon-fed Godavari River basin in India. We find that these lipids trace the mobilisation and transport of SOC in the wet season but that these lipids are not transferred far into the sea. This suggests that the burial of SOC on the sea floor is limited here.
Niek Jesse Speetjens, George Tanski, Victoria Martin, Julia Wagner, Andreas Richter, Gustaf Hugelius, Chris Boucher, Rachele Lodi, Christian Knoblauch, Boris P. Koch, Urban Wünsch, Hugues Lantuit, and Jorien E. Vonk
Biogeosciences, 19, 3073–3097, https://doi.org/10.5194/bg-19-3073-2022, https://doi.org/10.5194/bg-19-3073-2022, 2022
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Climate change and warming in the Arctic exceed global averages. As a result, permanently frozen soils (permafrost) which store vast quantities of carbon in the form of dead plant material (organic matter) are thawing. Our study shows that as permafrost landscapes degrade, high concentrations of organic matter are released. Partly, this organic matter is degraded rapidly upon release, while another significant fraction enters stream networks and enters the Arctic Ocean.
Thorben Dunse, Kaixing Dong, Kjetil Schanke Aas, and Leif Christian Stige
Biogeosciences, 19, 271–294, https://doi.org/10.5194/bg-19-271-2022, https://doi.org/10.5194/bg-19-271-2022, 2022
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We investigate the effect of glacier meltwater on phytoplankton dynamics in Svalbard. Phytoplankton forms the basis of the marine food web, and its seasonal dynamics depend on the availability of light and nutrients, both of which are affected by glacier runoff. We use satellite ocean color, an indicator of phytoplankton biomass, and glacier mass balance modeling to find that the overall effect of glacier runoff on marine productivity is positive within the major fjord systems of Svalbard.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 18, 5327–5350, https://doi.org/10.5194/bg-18-5327-2021, https://doi.org/10.5194/bg-18-5327-2021, 2021
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Nitrogen is one of the most important elements for life in the ocean. A major source is the riverine discharge of dissolved nitrogen. While global models often omit rivers as a nutrient source, we included nitrogen from rivers in our Earth system model and found that additional nitrogen affected marine biology not only locally but also in regions far off the coast. Depending on regional conditions, primary production was enhanced or even decreased due to internal feedbacks in the nitrogen cycle.
Kyra A. St. Pierre, Brian P. V. Hunt, Suzanne E. Tank, Ian Giesbrecht, Maartje C. Korver, William C. Floyd, Allison A. Oliver, and Kenneth P. Lertzman
Biogeosciences, 18, 3029–3052, https://doi.org/10.5194/bg-18-3029-2021, https://doi.org/10.5194/bg-18-3029-2021, 2021
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Using 4 years of paired freshwater and marine water chemistry from the Central Coast of British Columbia (Canada), we show that coastal temperate rainforest streams are sources of organic nitrogen, iron, and carbon to the Pacific Ocean but not the inorganic nutrients easily used by marine phytoplankton. This distinction may have important implications for coastal food webs and highlights the need to sample all nutrients in fresh and marine waters year-round to fully understand coastal dynamics.
Thomas S. Bianchi, Madhur Anand, Chris T. Bauch, Donald E. Canfield, Luc De Meester, Katja Fennel, Peter M. Groffman, Michael L. Pace, Mak Saito, and Myrna J. Simpson
Biogeosciences, 18, 3005–3013, https://doi.org/10.5194/bg-18-3005-2021, https://doi.org/10.5194/bg-18-3005-2021, 2021
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Better development of interdisciplinary ties between biology, geology, and chemistry advances biogeochemistry through (1) better integration of contemporary (or rapid) evolutionary adaptation to predict changing biogeochemical cycles and (2) universal integration of data from long-term monitoring sites in terrestrial, aquatic, and human systems that span broad geographical regions for use in modeling.
Anna Rose Canning, Peer Fietzek, Gregor Rehder, and Arne Körtzinger
Biogeosciences, 18, 1351–1373, https://doi.org/10.5194/bg-18-1351-2021, https://doi.org/10.5194/bg-18-1351-2021, 2021
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The paper describes a novel, fully autonomous, multi-gas flow-through set-up for multiple gases that combines established, high-quality oceanographic sensors in a small and robust system designed for use across all salinities and all types of platforms. We describe the system and its performance in all relevant detail, including the corrections which improve the accuracy of these sensors, and illustrate how simultaneous multi-gas set-ups can provide an extremely high spatiotemporal resolution.
Joonas J. Virtasalo, Peter Österholm, Aarno T. Kotilainen, and Mats E. Åström
Biogeosciences, 17, 6097–6113, https://doi.org/10.5194/bg-17-6097-2020, https://doi.org/10.5194/bg-17-6097-2020, 2020
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Rivers draining the acid sulphate soils of western Finland deliver large amounts of metals (e.g. Cd, Co, Cu, La, Mn, Ni, and Zn) to the coastal sea. To better understand metal enrichment in the sea floor, we analysed metal contents and grain size distribution in nine sediment cores, which increased in the 1960s and 1970s and stayed at high levels afterwards. The enrichment is visible more than 25 km out from the river mouths. Organic aggregates are suggested as the key seaward metal carriers.
Simon David Herzog, Per Persson, Kristina Kvashnina, and Emma Sofia Kritzberg
Biogeosciences, 17, 331–344, https://doi.org/10.5194/bg-17-331-2020, https://doi.org/10.5194/bg-17-331-2020, 2020
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Fe concentrations in boreal rivers are increasing strongly in several regions in Northern Europe. This study focuses on how Fe speciation and interaction with organic matter affect stability of Fe across estuarine salinity gradients. The results confirm a positive relationship between the relative contribution of organically complexed Fe and stability. Moreover, organically complexed Fe was more prevalent at high flow conditions and more dominant further upstream in a catchment.
Ines Bartl, Dana Hellemann, Christophe Rabouille, Kirstin Schulz, Petra Tallberg, Susanna Hietanen, and Maren Voss
Biogeosciences, 16, 3543–3564, https://doi.org/10.5194/bg-16-3543-2019, https://doi.org/10.5194/bg-16-3543-2019, 2019
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Irrespective of variable environmental settings in estuaries, the quality of organic particles is an important factor controlling microbial processes that facilitate a reduction of land-derived nitrogen loads to the open sea. Through the interplay of biogeochemical processing, geomorphology, and hydrodynamics, organic particles may function as a carrier and temporary reservoir of nitrogen, which has a major impact on the efficiency of nitrogen load reduction.
Moturi S. Krishna, Rongali Viswanadham, Mamidala H. K. Prasad, Vuravakonda R. Kumari, and Vedula V. S. S. Sarma
Biogeosciences, 16, 505–519, https://doi.org/10.5194/bg-16-505-2019, https://doi.org/10.5194/bg-16-505-2019, 2019
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An order-of-magnitude variability in DIC was found within the Indian estuaries due to significant variability in size of rivers, precipitation pattern and lithology in the catchments. Indian monsoonal estuaries annually export ∼ 10.3 Tg of DIC to the northern Indian Ocean, of which 75 % enters into the Bay of Bengal. Our results indicated that chemical weathering of carbonate and silicate minerals by soil CO2 is the major source of DIC in the Indian monsoonal rivers.
Tim Rixen, Birgit Gaye, Kay-Christian Emeis, and Venkitasubramani Ramaswamy
Biogeosciences, 16, 485–503, https://doi.org/10.5194/bg-16-485-2019, https://doi.org/10.5194/bg-16-485-2019, 2019
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Data obtained from sediment trap experiments in the Indian Ocean indicate that lithogenic matter ballast increases organic carbon flux rates on average by 45 % and by up to 62 % at trap locations in the river-influenced regions of the Indian Ocean. Such a strong lithogenic matter ballast effect implies that land use changes and the associated enhanced transport of lithogenic matter may significantly affect the CO2 uptake of the organic carbon pump in the receiving ocean areas.
Yongping Yuan, Ruoyu Wang, Ellen Cooter, Limei Ran, Prasad Daggupati, Dongmei Yang, Raghavan Srinivasan, and Anna Jalowska
Biogeosciences, 15, 7059–7076, https://doi.org/10.5194/bg-15-7059-2018, https://doi.org/10.5194/bg-15-7059-2018, 2018
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Elevated levels of nutrients in surface water, which originate from deposition of atmospheric N, drainage from agricultural fields, and discharges from sewage treatment plants, cause explosive algal blooms that impair water quality. The complex cycling of nutrients through the land, air, and water requires an integrated multimedia modeling system linking air, land surface, and stream processes to assess their sources, transport, and transformation in large river basins for decision making.
Muhammed Ojoshogu Usman, Frédérique Marie Sophie Anne Kirkels, Huub Michel Zwart, Sayak Basu, Camilo Ponton, Thomas Michael Blattmann, Michael Ploetze, Negar Haghipour, Cameron McIntyre, Francien Peterse, Maarten Lupker, Liviu Giosan, and Timothy Ian Eglinton
Biogeosciences, 15, 3357–3375, https://doi.org/10.5194/bg-15-3357-2018, https://doi.org/10.5194/bg-15-3357-2018, 2018
Tom Jilbert, Eero Asmala, Christian Schröder, Rosa Tiihonen, Jukka-Pekka Myllykangas, Joonas J. Virtasalo, Aarno Kotilainen, Pasi Peltola, Päivi Ekholm, and Susanna Hietanen
Biogeosciences, 15, 1243–1271, https://doi.org/10.5194/bg-15-1243-2018, https://doi.org/10.5194/bg-15-1243-2018, 2018
Short summary
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Iron is a common dissolved element in river water, recognizable by its orange-brown colour. Here we show that when rivers reach the ocean much of this iron settles to the sediments by a process known as flocculation. The iron is then used by microbes in coastal sediments, which are important hotspots in the global carbon cycle.
Shin-Ah Lee and Guebuem Kim
Biogeosciences, 15, 1115–1122, https://doi.org/10.5194/bg-15-1115-2018, https://doi.org/10.5194/bg-15-1115-2018, 2018
Short summary
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The fluorescent dissolved organic matter (FDOM) delivered from riverine discharges significantly affects carbon and biogeochemical cycles in coastal waters. Our results show that the terrestrial concentrations of humic-like FDOM in river water were 60–80 % higher in the summer and fall, while the in situ production of protein-like FDOM was 70–80 % higher in the spring. Our results suggest that there are large seasonal changes in riverine fluxes of FDOM components to the ocean.
Yafei Zhu, Andrew McCowan, and Perran L. M. Cook
Biogeosciences, 14, 4423–4433, https://doi.org/10.5194/bg-14-4423-2017, https://doi.org/10.5194/bg-14-4423-2017, 2017
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We used a 3-D coupled hydrodynamic–biogeochemical water quality model to investigate the effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system. The results highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.
Kamilla S. Sjøgaard, Alexander H. Treusch, and Thomas B. Valdemarsen
Biogeosciences, 14, 4375–4389, https://doi.org/10.5194/bg-14-4375-2017, https://doi.org/10.5194/bg-14-4375-2017, 2017
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Permanent flooding of low-lying coastal areas is a growing threat due to climate-change-related sea-level rise. To reduce coastal damage, buffer zones can be created by managed coastal realignment where existing dykes are breached and new dykes are built further inland. We studied the impacts on organic matter degradation in soils flooded with seawater by managed coastal realignment and suggest that most of the organic carbon present in coastal soils will be permanently preserved after flooding.
Allison A. Oliver, Suzanne E. Tank, Ian Giesbrecht, Maartje C. Korver, William C. Floyd, Paul Sanborn, Chuck Bulmer, and Ken P. Lertzman
Biogeosciences, 14, 3743–3762, https://doi.org/10.5194/bg-14-3743-2017, https://doi.org/10.5194/bg-14-3743-2017, 2017
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Rivers draining small watersheds of the outer coastal Pacific temperate rainforest export some of the highest yields of dissolved organic carbon (DOC) in the world directly to the ocean. This DOC is largely derived from soils and terrestrial plants. Rainfall, temperature, and watershed characteristics such as wetlands and lakes are important controls on DOC export. This region may be significant for carbon export and linking terrestrial carbon to marine ecosystems.
Mathilde Couturier, Gwendoline Tommi-Morin, Maude Sirois, Alexandra Rao, Christian Nozais, and Gwénaëlle Chaillou
Biogeosciences, 14, 3321–3336, https://doi.org/10.5194/bg-14-3321-2017, https://doi.org/10.5194/bg-14-3321-2017, 2017
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At the land–ocean interface, subterranean estuaries (STEs) are a critical transition pathway of nitrogen. Environmental conditions in the groundwater lead to nitrogen transformation, altering the nitrogen species and concentrations exported to the coastal ocean. This study highlights the role of a STE in processing groundwater-derived N in a shallow boreal STE, far from anthropogenic pressures. Biogeochemical transformations provide new N species from terrestrial origin to the coastal ocean.
Elin Almroth-Rosell, Moa Edman, Kari Eilola, H. E. Markus Meier, and Jörgen Sahlberg
Biogeosciences, 13, 5753–5769, https://doi.org/10.5194/bg-13-5753-2016, https://doi.org/10.5194/bg-13-5753-2016, 2016
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Nutrients from land have been discussed to increase eutrophication in the open sea. This model study shows that the coastal zone works as an efficient filter. Water depth and residence time regulate the retention that occurs mostly in the sediment due to processes such as burial and denitrification. On shorter timescales the retention capacity might seem less effective when the land load of nutrients decreases, but with time the coastal zone can import nutrients from the open sea.
B. W. Abbott, J. B. Jones, S. E. Godsey, J. R. Larouche, and W. B. Bowden
Biogeosciences, 12, 3725–3740, https://doi.org/10.5194/bg-12-3725-2015, https://doi.org/10.5194/bg-12-3725-2015, 2015
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As high latitudes warm, carbon and nitrogen stored in permafrost soil will be vulnerable to erosion and transport to Arctic streams and rivers. We sampled outflow from 83 permafrost collapse features in Alaska. Permafrost collapse caused substantial increases in dissolved organic carbon and inorganic nitrogen but decreased methane concentration by 90%. Upland thermokarst may be a dominant linkage transferring carbon and nutrients from terrestrial to aquatic ecosystems as the Arctic warms.
V. Le Fouest, M. Manizza, B. Tremblay, and M. Babin
Biogeosciences, 12, 3385–3402, https://doi.org/10.5194/bg-12-3385-2015, https://doi.org/10.5194/bg-12-3385-2015, 2015
G. G. Laruelle, R. Lauerwald, J. Rotschi, P. A. Raymond, J. Hartmann, and P. Regnier
Biogeosciences, 12, 1447–1458, https://doi.org/10.5194/bg-12-1447-2015, https://doi.org/10.5194/bg-12-1447-2015, 2015
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This study quantifies the exchange of carbon dioxide (CO2) between the atmosphere and the land-ocean aquatic continuum (LOAC) of the northeast North American coast, which consists of rivers, estuaries, and the coastal ocean. Our analysis reveals significant variations of the flux intensity both in time and space across the study area. Ice cover, snowmelt, and the intensity of the estuarine filter are identified as important control factors of the CO2 exchange along the LOAC.
O. Arnalds, H. Olafsson, and P. Dagsson-Waldhauserova
Biogeosciences, 11, 6623–6632, https://doi.org/10.5194/bg-11-6623-2014, https://doi.org/10.5194/bg-11-6623-2014, 2014
Short summary
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Iceland is one of the largest dust sources on Earth. Based on two separate methods, we estimate dust emissions to range between 30 and 40 million tons annually. Ocean deposition ranges between 5.5 and 13.8 million tons. Calculated iron deposition in oceans around Iceland ranges between 0.56 to 1.4 million tons, which are distributed over wide areas. Iron is a limiting nutrient for primary production in these waters, and dust is likely to affect oceanic Fe levels around Iceland.
N. I. W. Leblans, B. D. Sigurdsson, P. Roefs, R. Thuys, B. Magnússon, and I. A. Janssens
Biogeosciences, 11, 6237–6250, https://doi.org/10.5194/bg-11-6237-2014, https://doi.org/10.5194/bg-11-6237-2014, 2014
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We studied the influence of allochthonous N inputs on primary succession and soil development of a 50-year-old volcanic island, Surtsey. Seabirds increased the ecosystem N accumulation rate inside their colony to ~47 kg ha-1 y-1, compared to 0.7 kg ha-1 y-1 outside it. A strong relationship was found between total ecosystem N stock and both total above- and belowground biomass and SOC stock, which shows how fast external N input can boost primary succession and soil formation.
J.-É. Tremblay, P. Raimbault, N. Garcia, B. Lansard, M. Babin, and J. Gagnon
Biogeosciences, 11, 4853–4868, https://doi.org/10.5194/bg-11-4853-2014, https://doi.org/10.5194/bg-11-4853-2014, 2014
H. E. Reader, C. A. Stedmon, and E. S. Kritzberg
Biogeosciences, 11, 3409–3419, https://doi.org/10.5194/bg-11-3409-2014, https://doi.org/10.5194/bg-11-3409-2014, 2014
R. Death, J. L. Wadham, F. Monteiro, A. M. Le Brocq, M. Tranter, A. Ridgwell, S. Dutkiewicz, and R. Raiswell
Biogeosciences, 11, 2635–2643, https://doi.org/10.5194/bg-11-2635-2014, https://doi.org/10.5194/bg-11-2635-2014, 2014
R. H. Li, S. M. Liu, Y. W. Li, G. L. Zhang, J. L. Ren, and J. Zhang
Biogeosciences, 11, 481–506, https://doi.org/10.5194/bg-11-481-2014, https://doi.org/10.5194/bg-11-481-2014, 2014
E. Asmala, R. Autio, H. Kaartokallio, L. Pitkänen, C. A. Stedmon, and D. N. Thomas
Biogeosciences, 10, 6969–6986, https://doi.org/10.5194/bg-10-6969-2013, https://doi.org/10.5194/bg-10-6969-2013, 2013
C. Buzzelli, Y. Wan, P. H. Doering, and J. N. Boyer
Biogeosciences, 10, 6721–6736, https://doi.org/10.5194/bg-10-6721-2013, https://doi.org/10.5194/bg-10-6721-2013, 2013
S. Nagao, M. Kanamori, S. Ochiai, S. Tomihara, K. Fukushi, and M. Yamamoto
Biogeosciences, 10, 6215–6223, https://doi.org/10.5194/bg-10-6215-2013, https://doi.org/10.5194/bg-10-6215-2013, 2013
V. Le Fouest, M. Babin, and J.-É. Tremblay
Biogeosciences, 10, 3661–3677, https://doi.org/10.5194/bg-10-3661-2013, https://doi.org/10.5194/bg-10-3661-2013, 2013
A. Rumín-Caparrós, A. Sanchez-Vidal, A. Calafat, M. Canals, J. Martín, P. Puig, and R. Pedrosa-Pàmies
Biogeosciences, 10, 3493–3505, https://doi.org/10.5194/bg-10-3493-2013, https://doi.org/10.5194/bg-10-3493-2013, 2013
M. A. Charette, C. F. Breier, P. B. Henderson, S. M. Pike, I. I. Rypina, S. R. Jayne, and K. O. Buesseler
Biogeosciences, 10, 2159–2167, https://doi.org/10.5194/bg-10-2159-2013, https://doi.org/10.5194/bg-10-2159-2013, 2013
B. Deutsch, V. Alling, C. Humborg, F. Korth, and C. M. Mörth
Biogeosciences, 9, 4465–4475, https://doi.org/10.5194/bg-9-4465-2012, https://doi.org/10.5194/bg-9-4465-2012, 2012
P. A. Faber, A. J. Kessler, J. K. Bull, I. D. McKelvie, F. J. R. Meysman, and P. L. M. Cook
Biogeosciences, 9, 4087–4097, https://doi.org/10.5194/bg-9-4087-2012, https://doi.org/10.5194/bg-9-4087-2012, 2012
M. E. Dueker, G. D. O'Mullan, K. C. Weathers, A. R. Juhl, and M. Uriarte
Biogeosciences, 9, 803–813, https://doi.org/10.5194/bg-9-803-2012, https://doi.org/10.5194/bg-9-803-2012, 2012
L. Lassaletta, E. Romero, G. Billen, J. Garnier, H. García-Gómez, and J. V. Rovira
Biogeosciences, 9, 57–70, https://doi.org/10.5194/bg-9-57-2012, https://doi.org/10.5194/bg-9-57-2012, 2012
J. Yu, Y. Fu, Y. Li, G. Han, Y. Wang, D. Zhou, W. Sun, Y. Gao, and F. X. Meixner
Biogeosciences, 8, 2427–2435, https://doi.org/10.5194/bg-8-2427-2011, https://doi.org/10.5194/bg-8-2427-2011, 2011
E. S. Karlsson, A. Charkin, O. Dudarev, I. Semiletov, J. E. Vonk, L. Sánchez-García, A. Andersson, and Ö. Gustafsson
Biogeosciences, 8, 1865–1879, https://doi.org/10.5194/bg-8-1865-2011, https://doi.org/10.5194/bg-8-1865-2011, 2011
C. Y. Bernard, H. H. Dürr, C. Heinze, J. Segschneider, and E. Maier-Reimer
Biogeosciences, 8, 551–564, https://doi.org/10.5194/bg-8-551-2011, https://doi.org/10.5194/bg-8-551-2011, 2011
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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.
Based on a 2-year monitoring study, we found that the freshwater system of the Danube Delta,...
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