Articles | Volume 16, issue 2
https://doi.org/10.5194/bg-16-485-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/bg-16-485-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
29 Jan 2019
Research article |
| 29 Jan 2019
| 29 Jan 2019
The ballast effect of lithogenic matter and its influences on the carbon fluxes in the Indian Ocean
Leibniz Center for Tropical Marine Research, 28359 Bremen, Germany
Institute for Geology, University of Hamburg, 20146 Hamburg,
Germany
Birgit Gaye
Institute for Geology, University of Hamburg, 20146 Hamburg,
Germany
Kay-Christian Emeis
Institute for Geology, University of Hamburg, 20146 Hamburg,
Germany
Helmholtz-Zentrum Geesthacht, Institute of Coastal Research,
21502 Geesthacht, Germany
Venkitasubramani Ramaswamy
National Institute of Oceanography, Dona Paula, Goa, 403004, India
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Southeast Asian peat-draining rivers are potentially strong sources of carbon to the atmosphere due to the large amounts of organic carbon stored in those ecosystems. We present the first assessment of CO2 emissions from the Rajang River, the largest peat-draining river in Malaysia. The peatlands’ influence on the CO2 emissions from the Rajang River was smaller than expected, probably due to their proximity to the coast. Therefore, the Rajang was only a moderate source of CO2 to the atmosphere.
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Tropical peat-draining rivers contain high amounts of carbon. Surprisingly, measured carbon dioxide (CO2) emissions from those rivers are comparatively moderate. We compiled data from 10 Southeast Asian rivers and found that CO2 production within these rivers is hampered by low water pH, providing a natural threshold for CO2 emissions. Furthermore, we find that enhanced carbonate input, e.g. caused by human activities, suspends this natural threshold and causes increased CO2 emissions.
Shichao Tian, Birgit Gaye, Jianhui Tang, Yongming Luo, Wenguo Li, Niko Lahajnar, Kirstin Dähnke, Tina Sanders, Tianqi Xiong, Weidong Zhai, and Kay-Christian Emeis
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We constrain the nitrogen budget and in particular the internal sources and sinks of nitrate in the Bohai Sea by using a mass-based and dual stable isotope approach based on δ15N and δ18O of nitrate. Based on available mass fluxes and isotope data an updated nitrogen budget is proposed. Compared to previous estimates, it is more complete and includes the impact of the interior cycle (nitrification) on the nitrate pool. The main external nitrogen sources are rivers contributing 19.2 %–25.6 %.
Birgit Gaye, Niko Lahajnar, Natalie Harms, Sophie Anna Luise Paul, Tim Rixen, and Kay-Christian Emeis
Biogeosciences, 19, 807–830, https://doi.org/10.5194/bg-19-807-2022, https://doi.org/10.5194/bg-19-807-2022, 2022
Short summary
Short summary
Amino acids were analyzed in a large number of samples of particulate and dissolved organic matter from coastal regions and the open ocean. A statistical analysis produced two new biogeochemical indicators. An indicator of sinking particle and sediment degradation (SDI) traces the degradation of organic matter from the surface waters into the sediments. A second indicator shows the residence time of suspended matter in the ocean (RTI).
Nicole Burdanowitz, Tim Rixen, Birgit Gaye, and Kay-Christian Emeis
Clim. Past, 17, 1735–1749, https://doi.org/10.5194/cp-17-1735-2021, https://doi.org/10.5194/cp-17-1735-2021, 2021
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Tim Rixen, Greg Cowie, Birgit Gaye, Joaquim Goes, Helga do Rosário Gomes, Raleigh R. Hood, Zouhair Lachkar, Henrike Schmidt, Joachim Segschneider, and Arvind Singh
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Nele Tim, Eduardo Zorita, Kay-Christian Emeis, Franziska U. Schwarzkopf, Arne Biastoch, and Birgit Hünicke
Earth Syst. Dynam., 10, 847–858, https://doi.org/10.5194/esd-10-847-2019, https://doi.org/10.5194/esd-10-847-2019, 2019
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Our study reveals that the latitudinal position and intensity of Southern Hemisphere trades and westerlies are correlated. In the last decades the westerlies have shifted poleward and intensified. Furthermore, the latitudinal shifts and intensity of the trades and westerlies impact the sea surface temperatures around southern Africa and in the South Benguela upwelling region. The future development of wind stress depends on the strength of greenhouse gas forcing.
Shan Jiang, Moritz Müller, Jie Jin, Ying Wu, Kun Zhu, Guosen Zhang, Aazani Mujahid, Tim Rixen, Mohd Fakharuddin Muhamad, Edwin Sien Aun Sia, Faddrine Holt Ajon Jang, and Jing Zhang
Biogeosciences, 16, 2821–2836, https://doi.org/10.5194/bg-16-2821-2019, https://doi.org/10.5194/bg-16-2821-2019, 2019
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Three cruises were conducted in the Rajang River estuary, Malaysia. The results revealed that the decomposition of terrestrial organic matter and the subsequent soil leaching were the main sources of dissolved inorganic nitrogen (DIN) in the fresh river water. Porewater exchange and ammonification enhanced DIN concentrations in the estuary water, while intensities of DIN addition varied between seasons. The riverine DIN flux could reach 101.5 ton(N) / d, supporting the coastal primary producers.
Natalie C. Harms, Niko Lahajnar, Birgit Gaye, Tim Rixen, Kirstin Dähnke, Markus Ankele, Ulrich Schwarz-Schampera, and Kay-Christian Emeis
Biogeosciences, 16, 2715–2732, https://doi.org/10.5194/bg-16-2715-2019, https://doi.org/10.5194/bg-16-2715-2019, 2019
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The Indian Ocean subtropical gyre is a large oligotrophic area that is likely to adjust to continued warming by increasing stratification, reduced nutrient supply and decreasing biological production. In this study, we investigated concentrations of nutrients and stable isotopes of nitrate. We determine the lateral influence of water masses entering the gyre from the northern Indian Ocean and from the Southern Ocean and quantify the input of nitrogen by N2 fixation into the surface layer.
Denise Müller-Dum, Thorsten Warneke, Tim Rixen, Moritz Müller, Antje Baum, Aliki Christodoulou, Joanne Oakes, Bradley D. Eyre, and Justus Notholt
Biogeosciences, 16, 17–32, https://doi.org/10.5194/bg-16-17-2019, https://doi.org/10.5194/bg-16-17-2019, 2019
Short summary
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Southeast Asian peat-draining rivers are potentially strong sources of carbon to the atmosphere due to the large amounts of organic carbon stored in those ecosystems. We present the first assessment of CO2 emissions from the Rajang River, the largest peat-draining river in Malaysia. The peatlands’ influence on the CO2 emissions from the Rajang River was smaller than expected, probably due to their proximity to the coast. Therefore, the Rajang was only a moderate source of CO2 to the atmosphere.
Celeste Sánchez-Noguera, Ines Stuhldreier, Jorge Cortés, Carlos Jiménez, Álvaro Morales, Christian Wild, and Tim Rixen
Biogeosciences, 15, 2349–2360, https://doi.org/10.5194/bg-15-2349-2018, https://doi.org/10.5194/bg-15-2349-2018, 2018
Short summary
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The Papagayo upwelling system is a natural laboratory for studying ecosystems' response to ocean acidification (OA). We measured pH and pCO2 in situ with high temporal resolution and compared them with data available from upwelling season. Local coral reefs are exposed to acidic and undersaturated waters in upwelling and non-upwelling events. These restrictive conditions occur alongside local stressors, potentially decreasing reefs' resilience and increasing their vulnerability under future OA.
Birgit Gaye, Anna Böll, Joachim Segschneider, Nicole Burdanowitz, Kay-Christian Emeis, Venkitasubramani Ramaswamy, Niko Lahajnar, Andreas Lückge, and Tim Rixen
Biogeosciences, 15, 507–527, https://doi.org/10.5194/bg-15-507-2018, https://doi.org/10.5194/bg-15-507-2018, 2018
Short summary
Short summary
The Arabian Sea has one of the most severe oxygen minima of the world's oceans between about 100 and 1200 m of water depth and is therefore a major oceanic nitrogen sink. Stable nitrogen isotopic ratios in sediments record changes in oxygen concentrations and were studied for the last 25 kyr. Oxygen concentrations dropped at the end of the last glacial and became further reduced during the Holocene, probably due to the increasing age of the low-oxygen water mass.
Valerie Menke, Werner Ehrmann, Yvonne Milker, Swaantje Brzelinski, Jürgen Möbius, Uwe Mikolajewicz, Bernd Zolitschka, Karin Zonneveld, Kay Christian Emeis, and Gerhard Schmiedl
Clim. Past Discuss., https://doi.org/10.5194/cp-2017-139, https://doi.org/10.5194/cp-2017-139, 2017
Preprint withdrawn
Short summary
Short summary
This study examines changes in the marine ecosystem during the past 1300 years in the Gulf of Taranto (Italy) to unravel natural and anthropogenic forcing. Our data suggest, that processes at the sea floor are linked to the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation. During the past 200 years, the effects of rising northern hemisphere temperature and increasing anthropogenic activity enhanced nutrient and organic matter fluxes leading to more eutrophic conditions.
Tim Rixen, Birgit Gaye, Kay-Christian Emeis, and Venkitasubramani Ramaswamy
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-317, https://doi.org/10.5194/bg-2017-317, 2017
Manuscript not accepted for further review
Short summary
Short summary
Sediment trap experiments showed that in the river-influenced regions of the Indian Ocean lithogenic matter supplied from land controls the organic carbon export into the deep sea via its ballast effect in sinking particles. Carbonate produced by plankton is the main ballast material in the open ocean. The ballast effect increases the CO2 uptake of the organic carbon pump by enhancing the amount of nutrients used to bind CO2 and by favouring the sedimentation of organic matter.
Nele Tim, Eduardo Zorita, Birgit Hünicke, Xing Yi, and Kay-Christian Emeis
Ocean Sci., 12, 807–823, https://doi.org/10.5194/os-12-807-2016, https://doi.org/10.5194/os-12-807-2016, 2016
Short summary
Short summary
The impact of external climate forcing on the four eastern boundary upwelling systems is investigated for the recent past and future. Under increased radiative forcing, upwelling-favourable winds should strengthen due to unequal heating of land and oceans. However, coastal upwelling simulated in ensembles of climate simulations do not show any imprint of external forcing neither for the past millennium nor for the future, with the exception of the strongest future scenario.
Denise Müller, Hermann W. Bange, Thorsten Warneke, Tim Rixen, Moritz Müller, Aazani Mujahid, and Justus Notholt
Biogeosciences, 13, 2415–2428, https://doi.org/10.5194/bg-13-2415-2016, https://doi.org/10.5194/bg-13-2415-2016, 2016
Short summary
Short summary
Estuaries act as sources of the greenhouse gases nitrous oxide (N2O) and methane (CH4) to the atmosphere. We provide first measurements of N2O and CH4 in two estuaries in north-western Borneo, a region which is dominated by peatlands. We show that N2O and CH4 concentrations in these estuaries are moderate despite high organic carbon loads, that nutrient enhancement does not lead to enhanced N2O emissions, and that the wet season dominates the variability of the emissions in these systems.
D. Müller, T. Warneke, T. Rixen, M. Müller, A. Mujahid, H. W. Bange, and J. Notholt
Biogeosciences, 13, 691–705, https://doi.org/10.5194/bg-13-691-2016, https://doi.org/10.5194/bg-13-691-2016, 2016
Short summary
Short summary
We studied organic carbon and the dissolved greenhouse gases carbon dioxide (CO2) and carbon monoxide (CO) in two estuaries in Sarawak, Malaysia, whose coast is covered by carbon-rich peatlands. The estuaries received terrestrial organic carbon from peat-draining tributaries. A large fraction was converted to CO2 and a minor fraction to CO. Both gases were released to the atmosphere. This shows how these estuaries function as efficient filters between land and ocean in this important region.
D. Müller, T. Warneke, T. Rixen, M. Müller, S. Jamahari, N. Denis, A. Mujahid, and J. Notholt
Biogeosciences, 12, 5967–5979, https://doi.org/10.5194/bg-12-5967-2015, https://doi.org/10.5194/bg-12-5967-2015, 2015
Short summary
Short summary
Tropical peatlands are an important source of organic carbon to rivers. However, due to the remoteness of these ecosystems, data are scarce. We present the first combined assessment of both lateral organic carbon fluxes and CO2 emissions from an undisturbed tropical peat-draining river. Compared to the organic carbon concentrations, CO2 fluxes to the atmosphere were actually relatively moderate, which we attributed to the short water residence time.
T. Rixen, A. Baum, B. Gaye, and B. Nagel
Biogeosciences, 11, 5733–5747, https://doi.org/10.5194/bg-11-5733-2014, https://doi.org/10.5194/bg-11-5733-2014, 2014
A. Flohr, A. K. van der Plas, K.-C. Emeis, V. Mohrholz, and T. Rixen
Biogeosciences, 11, 885–897, https://doi.org/10.5194/bg-11-885-2014, https://doi.org/10.5194/bg-11-885-2014, 2014
B. Gaye, B. Nagel, K. Dähnke, T. Rixen, N. Lahajnar, and K.-C. Emeis
Biogeosciences, 10, 7689–7702, https://doi.org/10.5194/bg-10-7689-2013, https://doi.org/10.5194/bg-10-7689-2013, 2013
Related subject area
Biogeochemistry: Land - Sea Coupling
Distinct impacts of the El Niño–Southern Oscillation and Indian Ocean Dipole on China's gross primary production
Atmospheric CO2 exchanges measured by eddy covariance over a temperate salt marsh and influence of environmental controlling factors
Characterization of the benthic biogeochemical dynamics after flood events in the Rhône River prodelta: a data–model approach
Recent inorganic carbon increase in a temperate estuary driven by water quality improvement and enhanced by droughts
Alkalinity and nitrate dynamics reveal dominance of anammox in a hyper-turbid estuary
Reconciling the paradox of soil organic carbon erosion by water
The dispersal of fluvially discharged and marine, shelf-produced particulate organic matter in the northern Gulf of Mexico
Carbon dynamics at the river–estuarine transition: a comparison among tributaries of Chesapeake Bay
From soil to sea: sources and transport of organic carbon traced by tetraether lipids in the monsoonal Godavari River, India
Dissolved organic matter characterization in soils and streams in a small coastal low-Arctic catchment
Regional-scale phytoplankton dynamics and their association with glacier meltwater runoff in Svalbard
Riverine nitrogen supply to the global ocean and its limited impact on global marine primary production: a feedback study using an Earth system model
Rain-fed streams dilute inorganic nutrients but subsidise organic-matter-associated nutrients in coastal waters of the northeast Pacific Ocean
Ideas and perspectives: Biogeochemistry – some key foci for the future
Spatio-temporal variations in lateral and atmospheric carbon fluxes from the Danube Delta
Technical note: Seamless gas measurements across the land–ocean aquatic continuum – corrections and evaluation of sensor data for CO2, CH4 and O2 from field deployments in contrasting environments
Enrichment of trace metals from acid sulfate soils in sediments of the Kvarken Archipelago, eastern Gulf of Bothnia, Baltic Sea
Organic iron complexes enhance iron transport capacity along estuarine salinity gradients of Baltic estuaries
Particulate organic matter controls benthic microbial N retention and N removal in contrasting estuaries of the Baltic Sea
Export fluxes of dissolved inorganic carbon to the northern Indian Ocean from the Indian monsoonal rivers
Integrating multimedia models to assess nitrogen losses from the Mississippi River basin to the Gulf of Mexico
Reconciling drainage and receiving basin signatures of the Godavari River system
Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments
Sources, fluxes, and behaviors of fluorescent dissolved organic matter (FDOM) in the Nakdong River Estuary, Korea
Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon
Carbon degradation in agricultural soils flooded with seawater after managed coastal realignment
A global hotspot for dissolved organic carbon in hypermaritime watersheds of coastal British Columbia
Nitrogen transformations along a shallow subterranean estuary
Modelling nutrient retention in the coastal zone of an eutrophic sea
Patterns and persistence of hydrologic carbon and nutrient export from collapsing upland permafrost
Modelling the impact of riverine DON removal by marine bacterioplankton on primary production in the Arctic Ocean
Seasonal response of air–water CO2 exchange along the land–ocean aquatic continuum of the northeast North American coast.
Quantification of iron-rich volcanogenic dust emissions and deposition over the ocean from Icelandic dust sources
Effects of seabird nitrogen input on biomass and carbon accumulation after 50 years of primary succession on a young volcanic island, Surtsey
Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf
Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments
Antarctic ice sheet fertilises the Southern Ocean
Nutrient dynamics in tropical rivers, lagoons, and coastal ecosystems of eastern Hainan Island, South China Sea
Bioavailability of riverine dissolved organic matter in three Baltic Sea estuaries and the effect of catchment land use
Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA
Export of 134 Cs and 137 Cs in the Fukushima river systems at heavy rains by Typhoon Roke in September 2011
The fate of riverine nutrients on Arctic shelves
External forcings, oceanographic processes and particle flux dynamics in Cap de Creus submarine canyon, NW Mediterranean Sea
Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident
Tracing inputs of terrestrial high molecular weight dissolved organic matter within the Baltic Sea ecosystem
The role of alkalinity generation in controlling the fluxes of CO2 during exposure and inundation on tidal flats
Coupling of fog and marine microbial content in the near-shore coastal environment
Spatialized N budgets in a large agricultural Mediterranean watershed: high loading and low transfer
Effects of water discharge and sediment load on evolution of modern Yellow River Delta, China, over the period from 1976 to 2009
Carbon isotopes and lipid biomarker investigation of sources, transport and degradation of terrestrial organic matter in the Buor-Khaya Bay, SE Laptev Sea
Ran Yan, Jun Wang, Weimin Ju, Xiuli Xing, Miao Yu, Meirong Wang, Jingye Tan, Xunmei Wang, Hengmao Wang, and Fei Jiang
Biogeosciences, 21, 5027–5043, https://doi.org/10.5194/bg-21-5027-2024, https://doi.org/10.5194/bg-21-5027-2024, 2024
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Our study reveals that the effects of the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on China's gross primary production (GPP) are basically opposite, with obvious seasonal changes. Soil moisture primarily influences GPP during ENSO events (except spring) and temperature during IOD events (except fall). Quantitatively, China's annual GPP displays modest positive anomalies during La Niña and negative anomalies in El Niño years, driven by significant seasonal variations.
Jérémy Mayen, Pierre Polsenaere, Éric Lamaud, Marie Arnaud, Pierre Kostyrka, Jean-Marc Bonnefond, Philippe Geairon, Julien Gernigon, Romain Chassagne, Thomas Lacoue-Labarthe, Aurore Regaudie de Gioux, and Philippe Souchu
Biogeosciences, 21, 993–1016, https://doi.org/10.5194/bg-21-993-2024, https://doi.org/10.5194/bg-21-993-2024, 2024
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We deployed an atmospheric eddy covariance system to measure continuously the net ecosystem CO2 exchanges (NEE) over a salt marsh and determine the major biophysical drivers. Our results showed an annual carbon sink mainly due to photosynthesis of the marsh plants. Our study also provides relevant information on NEE fluxes during marsh immersion by decreasing daytime CO2 uptake and night-time CO2 emissions at the daily scale, whereas the immersion did not affect the annual marsh C balance.
Eva Ferreira, Stanley Nmor, Eric Viollier, Bruno Lansard, Bruno Bombled, Edouard Regnier, Gaël Monvoisin, Christian Grenz, Pieter van Beek, and Christophe Rabouille
Biogeosciences, 21, 711–729, https://doi.org/10.5194/bg-21-711-2024, https://doi.org/10.5194/bg-21-711-2024, 2024
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The study provides new insights by examining the short-term impact of winter floods on biogeochemical sediment processes near the Rhône River (NW Mediterranean Sea). This is the first winter monitoring of sediment and porewater in deltaic areas. The coupling of these data with a new model enables us to quantify the evolution of biogeochemical processes. It also provides new perspectives on the benthic carbon cycle in river deltas considering climate change, whereby flooding should intensify.
Louise C. V. Rewrie, Burkard Baschek, Justus E. E. van Beusekom, Arne Körtzinger, Gregor Ollesch, and Yoana G. Voynova
Biogeosciences, 20, 4931–4947, https://doi.org/10.5194/bg-20-4931-2023, https://doi.org/10.5194/bg-20-4931-2023, 2023
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After heavy pollution in the 1980s, a long-term inorganic carbon increase in the Elbe Estuary (1997–2020) was fueled by phytoplankton and organic carbon production in the upper estuary, associated with improved water quality. A recent drought (2014–2020) modulated the trend, extending the water residence time and the dry summer season into May. The drought enhanced production of inorganic carbon in the estuary but significantly decreased the annual inorganic carbon export to coastal waters.
Mona Norbisrath, Andreas Neumann, Kirstin Dähnke, Tina Sanders, Andreas Schöl, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 20, 4307–4321, https://doi.org/10.5194/bg-20-4307-2023, https://doi.org/10.5194/bg-20-4307-2023, 2023
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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.
Kristof Van Oost and Johan Six
Biogeosciences, 20, 635–646, https://doi.org/10.5194/bg-20-635-2023, https://doi.org/10.5194/bg-20-635-2023, 2023
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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.
Yord W. Yedema, Francesca Sangiorgi, Appy Sluijs, Jaap S. Sinninghe Damsté, and Francien Peterse
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.
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
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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.
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.
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
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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
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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
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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
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Short summary
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.
Data obtained from sediment trap experiments in the Indian Ocean indicate that lithogenic matter...
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