Articles | Volume 12, issue 16
https://doi.org/10.5194/bg-12-4953-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-12-4953-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
19 Aug 2015
Research article |
| 19 Aug 2015
Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa: insights from a stable isotope study covering an annual cycle
C. Morana
CORRESPONDING AUTHOR
Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
F. Darchambeau
Chemical Oceanography Unit, Université de Liège, Liege, Belgium
F. A. E. Roland
Chemical Oceanography Unit, Université de Liège, Liege, Belgium
A. V. Borges
Chemical Oceanography Unit, Université de Liège, Liege, Belgium
F. Muvundja
Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur, Belgium
Unité d'Enseignement et de Recherche en Hydrobiologie Appliquée, ISP-Bukavu, Bukavu, Democratic Republic of the Congo
Z. Kelemen
Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
P. Masilya
Unité d'Enseignement et de Recherche en Hydrobiologie Appliquée, ISP-Bukavu, Bukavu, Democratic Republic of the Congo
J.-P. Descy
Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur, Belgium
S. Bouillon
Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
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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
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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.
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
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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. 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.
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
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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
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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.
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
W. Thiery, A. Martynov, F. Darchambeau, J.-P. Descy, P.-D. Plisnier, L. Sushama, and N. P. M. van Lipzig
Geosci. Model Dev., 7, 317–337, https://doi.org/10.5194/gmd-7-317-2014, https://doi.org/10.5194/gmd-7-317-2014, 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
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The nature of organic carbon in density-fractionated sediments in the Sacramento-San Joaquin River Delta (California)
Microbial nutrient limitation in Arctic lakes in a permafrost landscape of southwest Greenland
Ido Sirota, Rik Tjallingii, Sylvia Pinkerneil, Birgit Schroeder, Marlen Albert, Rebecca Kearney, Oliver Heiri, Simona Breu, and Achim Brauer
Biogeosciences, 21, 4317–4339, https://doi.org/10.5194/bg-21-4317-2024, https://doi.org/10.5194/bg-21-4317-2024, 2024
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Hypoxia has spread in Tiefer See (NE Germany) due to increased human activity. The onset of hypoxia indicated by varve preservation is dated to ~1920 at the lake’s depocenter, which responds faster and more severely to the reduction in oxygen level. The spread of hypoxic conditions is a gradual process that has lasted nearly 100 years, and the chemistry of the sediments shows that the depletion of oxygen in the lake started several decades before the onset of varve preservation.
Amelie Stieg, Boris K. Biskaborn, Ulrike Herzschuh, Andreas Marent, Jens Strauss, Dorothee Wilhelms–Dick, Luidmila A. Pestryakova, and Hanno Meyer
EGUsphere, https://doi.org/10.5194/egusphere-2024-2470, https://doi.org/10.5194/egusphere-2024-2470, 2024
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Globally, lake ecosystems have undergone significant shifts since the 1950s due to human activities. This study offers a unique 220-year sediment record from a remote Siberian boreal lake, revealing the impacts of climate warming and pollution. Multi-proxy analyses, including diatom taxonomy, silicon isotopes, carbon and nitrogen proxies, reveal complex biogeochemical interactions, highlighting the need for further research to mitigate anthropogenic effects on these vital water resources.
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
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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.
Elizabeth D. Swanner, Chris Harding, Sajjad A. Akam, Ioan Lascu, Gabrielle Ledesma, Pratik Poudel, Heeyeon Sun, Samuel Duncanson, Karly Bandy, Alex Branham, Liza Bryant-Tapper, Tanner Conwell, Omri Jamison, and Lauren Netz
Biogeosciences, 21, 1549–1562, https://doi.org/10.5194/bg-21-1549-2024, https://doi.org/10.5194/bg-21-1549-2024, 2024
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Four lakes were thought to be permanently stratified. Years’ worth of data indicate only one lake is permanently stratified. Strong temperature gradients keep it stratified – unusual for a lake in a temperate climate. The lake has elevated oxygen concentrations within the temperature gradient. Rapid development of the gradient in the spring traps oxygen, and oxygen production by photosynthetic organisms during the summer adds more.
Alice R. Paine, Isabel M. Fendley, Joost Frieling, Tamsin A. Mather, Jack H. Lacey, Bernd Wagner, Stuart A. Robinson, David M. Pyle, Alexander Francke, Theodore R. Them II, and Konstantinos Panagiotopoulos
Biogeosciences, 21, 531–556, https://doi.org/10.5194/bg-21-531-2024, https://doi.org/10.5194/bg-21-531-2024, 2024
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Many important processes within the global mercury (Hg) cycle operate over thousands of years. Here, we explore the timing, magnitude, and expression of Hg signals retained in sediments of lakes Prespa and Ohrid over the past ∼90 000 years. Divergent signals suggest that local differences in sediment composition, lake structure, and water balance influence the local Hg cycle and determine the extent to which sedimentary Hg signals reflect local- or global-scale environmental changes.
Thomas A. Davidson, Martin Søndergaard, Joachim Audet, Eti Levi, Chiara Esposito, Tuba Bucak, and Anders Nielsen
Biogeosciences, 21, 93–107, https://doi.org/10.5194/bg-21-93-2024, https://doi.org/10.5194/bg-21-93-2024, 2024
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Shallow lakes and ponds undergo frequent stratification in summer months. Here we studied how this affects greenhouse gas (GHG) emissions. We found that stratification caused anoxia in the bottom waters, driving increased GHG emissions, in particular methane released as bubbles. In addition, methane and carbon dioxide accumulated in the bottom waters during stratification, leading to large emissions when the lake mixed again.
Austin Delany, Robert Ladwig, Cal Buelo, Ellen Albright, and Paul C. Hanson
Biogeosciences, 20, 5211–5228, https://doi.org/10.5194/bg-20-5211-2023, https://doi.org/10.5194/bg-20-5211-2023, 2023
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Internal and external sources of organic carbon (OC) in lakes can contribute to oxygen depletion, but their relative contributions remain in question. To study this, we built a two-layer model to recreate processes relevant to carbon for six Wisconsin lakes. We found that internal OC was more important than external OC in depleting oxygen. This shows that it is important to consider both the fast-paced cycling of internally produced OC and the slower cycling of external OC when studying lakes.
Hao-Chi Lin, Keisuke Nakayama, Jeng-Wei Tsai, and Chih-Yu Chiu
Biogeosciences, 20, 4359–4376, https://doi.org/10.5194/bg-20-4359-2023, https://doi.org/10.5194/bg-20-4359-2023, 2023
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We successfully developed conceptual models to examine how dissolved carbon distributions change with climate within a small subtropical lake, considering both physical and biochemical processes. Typhoons controlled the seasonal and interannual variation in C fluxes due to large amounts of carbon loading and rapid mixing within the whole lake, resulting in the net primary production being 3.14 times higher in typhoon years than in non-typhoon years in Yuan‒Yang Lake.
Sigrid van Grinsven and Carsten Schubert
Biogeosciences, 20, 4213–4220, https://doi.org/10.5194/bg-20-4213-2023, https://doi.org/10.5194/bg-20-4213-2023, 2023
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Agriculture relies heavily on plastic mulch films, which may be transported to aquatic environments. We investigated the breakdown of soil-biodegradable agricultural mulch films in lake sediments. After 40 weeks, films were intact, and no significant CO2 or CH4 was produced from the biodegradable mulch films. We conclude that the mulch films we used have a low biodegradability in lake sediments. The sediment lacks the microbes needed to break down the biodegradable plastics that were used here.
Ricky Mwangada Mwanake, Gretchen Maria Gettel, Elizabeth Gachibu Wangari, Clarissa Glaser, Tobias Houska, Lutz Breuer, Klaus Butterbach-Bahl, and Ralf Kiese
Biogeosciences, 20, 3395–3422, https://doi.org/10.5194/bg-20-3395-2023, https://doi.org/10.5194/bg-20-3395-2023, 2023
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Despite occupying <1 %; of the globe, streams are significant sources of greenhouse gas (GHG) emissions. In this study, we determined anthropogenic effects on GHG emissions from streams. We found that anthropogenic-influenced streams had up to 20 times more annual GHG emissions than natural ones and were also responsible for seasonal peaks. Anthropogenic influences also altered declining GHG flux trends with stream size, with potential impacts on stream-size-based spatial upscaling techniques.
Laura Balzer, Carluvy Baptista-Salazar, Sofi Jonsson, and Harald Biester
Biogeosciences, 20, 1459–1472, https://doi.org/10.5194/bg-20-1459-2023, https://doi.org/10.5194/bg-20-1459-2023, 2023
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Toxic methylmercury (MeHg) in lakes can be enriched in fish and is harmful for humans. Phytoplankton is the entry point for MeHg into the aquatic food chain. We investigated seasonal MeHg concentrations in plankton of a productive lake. Our results show that high amounts of MeHg occur in algae and suspended matter in lakes and that productive lakes are hot spots of MeHg formation, which is mainly controlled by decomposition of algae organic matter and water-phase redox conditions.
Nathan J. Tomczyk, Amy D. Rosemond, Anna Kaz, and Jonathan P. Benstead
Biogeosciences, 20, 191–204, https://doi.org/10.5194/bg-20-191-2023, https://doi.org/10.5194/bg-20-191-2023, 2023
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Warming is expected to increase rates of microbial metabolism, but the effect of warming on nutrient demand is unclear. Our experiments demonstrate that microbial nutrient uptake increases less with temperature than metabolism, particularly when environmental nutrient concentrations are low. However, our simulation models suggest that warming may actually lead to declines in ecosystem-scale nutrient uptake as warming accelerates the depletion of carbon substrates required for microbial growth.
Chuanqiao Zhou, Yu Peng, Li Chen, Miaotong Yu, Muchun Zhou, Runze Xu, Lanqing Zhang, Siyuan Zhang, Xiaoguang Xu, Limin Zhang, and Guoxiang Wang
Biogeosciences, 19, 4351–4360, https://doi.org/10.5194/bg-19-4351-2022, https://doi.org/10.5194/bg-19-4351-2022, 2022
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The dramatical increase in SO42- concentration up to 100 mg L-1 in eutrophic lakes has aroused great attention. It enhanced the sulfate reduction to release a large amount of ΣS2- during cyanobacteria decomposition. The Fe2+ released from the iron reduction process is captured by ΣS2-, and finally the combination of iron and P was reduced, promoting the release of endogenous P. Therefore, increasing sulfate concentrations are shown to be a hidden promoter of eutrophication in shallow lakes.
Flora Mazoyer, Isabelle Laurion, and Milla Rautio
Biogeosciences, 19, 3959–3977, https://doi.org/10.5194/bg-19-3959-2022, https://doi.org/10.5194/bg-19-3959-2022, 2022
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Dissolved organic matter collected at the end of winter from a peatland thermokarst lake was highly transformed and degraded by sunlight, leading to bacterial stimulation and CO2 production, but a fraction was also potentially lost by photoflocculation. Over 18 days, 18 % of the incubated dissolved organic matter was lost under sunlight, while dark bacterial degradation was negligible. Sunlight could have a marked effect on carbon cycling in organic-rich thermokarst lakes after ice-off.
Clara Romero González-Quijano, Sonia Herrero Ortega, Peter Casper, Mark O. Gessner, and Gabriel A. Singer
Biogeosciences, 19, 2841–2853, https://doi.org/10.5194/bg-19-2841-2022, https://doi.org/10.5194/bg-19-2841-2022, 2022
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Despite today's diversity of methods to measure dissolved organic matter (DOM), its potential to give ecological information about urban surface waters has been underused. We found DOM from urban lakes and ponds to differ greatly from that of urban streams and rivers in composition as well as temporal turnover. Urban land use (the percentage of green space), nutrient supply and point source pollution were the principal drivers of DOM. We suggest including DOM composition in regular monitoring.
Madeleine Moyle, John F. Boyle, and Richard C. Chiverrell
Biogeosciences, 18, 5609–5638, https://doi.org/10.5194/bg-18-5609-2021, https://doi.org/10.5194/bg-18-5609-2021, 2021
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We reconstruct Holocene landscape P yield and lake water TP concentration for 24 sites across the Northern Hemisphere by applying a process model to published lake sediment geochemical records. We find sites with the same landscape development history show similar geochemical profiles depending on climate, human impact, and other local factors. Our reconstructions can be used to understand present-day terrestrial P cycling, lake water nutrient status, and export of terrestrial P to the oceans.
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.
Ove H. Meisel, Joshua F. Dean, Jorien E. Vonk, Lukas Wacker, Gert-Jan Reichart, and Han Dolman
Biogeosciences, 18, 2241–2258, https://doi.org/10.5194/bg-18-2241-2021, https://doi.org/10.5194/bg-18-2241-2021, 2021
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Arctic permafrost lakes form thaw bulbs of unfrozen soil (taliks) beneath them where carbon degradation and greenhouse gas production are increased. We analyzed the stable carbon isotopes of Alaskan talik sediments and their porewater dissolved organic carbon and found that the top layers of these taliks are likely more actively degraded than the deeper layers. This in turn implies that these top layers are likely also more potent greenhouse gas producers than the underlying deeper layers.
Stamatina Makri, Andrea Lami, Luyao Tu, Wojciech Tylmann, Hendrik Vogel, and Martin Grosjean
Biogeosciences, 18, 1839–1856, https://doi.org/10.5194/bg-18-1839-2021, https://doi.org/10.5194/bg-18-1839-2021, 2021
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Anoxia in lakes is a major growing concern. In this study we applied a multiproxy approach combining high-resolution hyperspectral imaging (HSI) pigment data with specific HPLC data to examine the Holocene evolution and main drivers of lake anoxia and trophic state changes. We find that when human impact was low, these changes were driven by climate and natural lake-catchment evolution. In the last 500 years, increasing human impact has promoted lake eutrophication and permanent anoxia.
Cynthia Soued and Yves T. Prairie
Biogeosciences, 18, 1333–1350, https://doi.org/10.5194/bg-18-1333-2021, https://doi.org/10.5194/bg-18-1333-2021, 2021
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Freshwater reservoirs emit greenhouse gases (GHGs, CO2 and CH4) to the atmosphere; however, the sources underlying these emissions are numerous, and their magnitude is not well known. This study quantifies surface CO2 and CH4 emissions and all their potential sources in a tropical reservoir. Results highlight the changes in GHG sources along the river–reservoir continuum, with internal metabolism being a key component but highly uncertain and challenging to estimate at an ecosystem scale.
Christopher M. Dempsey, Jennifer A. Brentrup, Sarah Magyan, Lesley B. Knoll, Hilary M. Swain, Evelyn E. Gaiser, Donald P. Morris, Michael T. Ganger, and Craig E. Williamson
Biogeosciences, 17, 6327–6340, https://doi.org/10.5194/bg-17-6327-2020, https://doi.org/10.5194/bg-17-6327-2020, 2020
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We looked at how terrestrial dissolved organic carbon (DOC) from the watersheds of four different lakes responded to both biodegradation (i.e., microbes) and photodegradation (i.e., sunlight). The traditional paradigm is that biodegradation is more important than photodegradation. Our research shows that, on short timescales (i.e., 7 d), sunlight is more important than microbes in degrading DOC. Interestingly, the lakes had different responses to sunlight based on their trophic status.
Luyao Tu, Paul Zander, Sönke Szidat, Ronald Lloren, and Martin Grosjean
Biogeosciences, 17, 2715–2729, https://doi.org/10.5194/bg-17-2715-2020, https://doi.org/10.5194/bg-17-2715-2020, 2020
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In a small, deep lake on the Swiss Plateau, net fluxes of labile P fractions in sediments that can be released to surface waters have been predominately controlled by past hypolimnetic anoxic conditions since the early 1900s. More than 40 years of hypolimnetic withdrawal can effectively reduce net P fluxes in sediments and internal P loads but not effectively decrease eutrophication. These findings should likely serve the management of deep eutrophic lakes in temperate zones.
Jiantao Cao, Zhiguo Rao, Fuxi Shi, and Guodong Jia
Biogeosciences, 17, 2521–2536, https://doi.org/10.5194/bg-17-2521-2020, https://doi.org/10.5194/bg-17-2521-2020, 2020
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BrGDGT distribution in Gonghai Lake is different from surrounding soils, and its derived temperature reflects a mean annual lake water temperature (LWT) that is higher than the mean annual air temperature (AT). The higher mean annual LWT is due to ice formation in winter that prevents thermal exchange between lake water and air.
Joachim Jansen, Brett F. Thornton, Alicia Cortés, Jo Snöälv, Martin Wik, Sally MacIntyre, and Patrick M. Crill
Biogeosciences, 17, 1911–1932, https://doi.org/10.5194/bg-17-1911-2020, https://doi.org/10.5194/bg-17-1911-2020, 2020
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Lakes are important emitters of the greenhouse gas methane. We use field observations and a model to evaluate the importance of known drivers of methane production and release. Fast and slow changes of the diffusive flux were governed by wind speed and sediment temperature, respectively. Increased turbulence enhanced release, but storms depleted the lakes of gas and limited emissions. Our findings may inform model studies on the effects of weather and climate change on lake methane emissions.
Gabrielle R. Quadra, Sebastian Sobek, José R. Paranaíba, Anastasija Isidorova, Fábio Roland, Roseilson do Vale, and Raquel Mendonça
Biogeosciences, 17, 1495–1505, https://doi.org/10.5194/bg-17-1495-2020, https://doi.org/10.5194/bg-17-1495-2020, 2020
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Hydropower is expanding in the Amazon Basin, but the potential effects of river damming on carbon fluxes cannot be gauged due to a lack of studies. We quantified, for the first time in an Amazonian reservoir, both organic carbon burial and the concentrations of methane in the sediments. We found that the dual role of sediments as both a carbon sink and methane source may be particularly pronounced in this Amazonian reservoir.
Adeline N. Y. Cojean, Jakob Zopfi, Alan Gerster, Claudia Frey, Fabio Lepori, and Moritz F. Lehmann
Biogeosciences, 16, 4705–4718, https://doi.org/10.5194/bg-16-4705-2019, https://doi.org/10.5194/bg-16-4705-2019, 2019
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Our results demonstrate the importance of oxygen in regulating the fate of nitrogen (N) in the sediments of Lake Lugano south basin, Switzerland. Hence, our study suggests that, by changing oxygen concentration in bottom waters, the seasonal water column turnover may significantly regulate the partitioning between N removal and N recycling in surface sediments, and it is likely that a similar pattern can be expected in a wide range of environments.
Boris K. Biskaborn, Larisa Nazarova, Lyudmila A. Pestryakova, Liudmila Syrykh, Kim Funck, Hanno Meyer, Bernhard Chapligin, Stuart Vyse, Ruslan Gorodnichev, Evgenii Zakharov, Rong Wang, Georg Schwamborn, Hannah L. Bailey, and Bernhard Diekmann
Biogeosciences, 16, 4023–4049, https://doi.org/10.5194/bg-16-4023-2019, https://doi.org/10.5194/bg-16-4023-2019, 2019
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To better understand time-series data in lake sediment cores in times of rapidly changing climate, we study within-lake spatial variabilities of environmental indicator data in 38 sediment surface samples along spatial habitat gradients in the boreal deep Lake Bolshoe Toko (Russia). Our methods comprise physicochemical as well as diatom and chironomid analyses. Species diversities vary according to benthic niches, while abiotic proxies depend on river input, water depth, and catchment lithology.
Jeremy McCormack, Finn Viehberg, Derya Akdemir, Adrian Immenhauser, and Ola Kwiecien
Biogeosciences, 16, 2095–2114, https://doi.org/10.5194/bg-16-2095-2019, https://doi.org/10.5194/bg-16-2095-2019, 2019
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We juxtapose changes in ostracod taxonomy, morphology (noding) and oxygen (δ18O) and carbon (δ13C) isotopic composition for the last 150 kyr with independent low-resolution salinity proxies. We demonstrate that for Lake Van, salinity is the most important factor influencing the composition of the ostracod assemblage and the formation of nodes on the valves of limnocytherinae species. Ostracod δ18O shows a higher sensibility towards climatic and hydrological variations than the bulk isotopy.
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.
Kateri R. Salk, George S. Bullerjahn, Robert Michael L. McKay, Justin D. Chaffin, and Nathaniel E. Ostrom
Biogeosciences, 15, 2891–2907, https://doi.org/10.5194/bg-15-2891-2018, https://doi.org/10.5194/bg-15-2891-2018, 2018
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This paper highlights dynamic nitrogen cycling in a freshwater estuary, with implications for harmful algal blooms and downstream nitrogen loading. Phytoplankton and microbes actively consumed nitrogen in this system, contributing to recycling of nitrogen within the system and permanent nitrogen removal, respectively. However, delivery of nitrogen from the river and fixation of atmospheric nitrogen by phytoplankton outweighed nitrogen uptake, resulting in variable downstream nitrogen delivery.
Luciana Pena Mello Brandão, Ludmila Silva Brighenti, Peter Anton Staehr, Eero Asmala, Philippe Massicotte, Denise Tonetta, Francisco Antônio Rodrigues Barbosa, Diego Pujoni, and José Fernandes Bezerra-Neto
Biogeosciences, 15, 2931–2943, https://doi.org/10.5194/bg-15-2931-2018, https://doi.org/10.5194/bg-15-2931-2018, 2018
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Using mesocosms we investigated the effect of the increase in the allochthonous and autochthonous sources of DOM in a tropical lake, in order to simulate its effects on the characteristics of lakes caused by anthropogenic impacts. The seasonal allochthonous input has much larger effects on the lake and, in addition to increasing nutrients, alters the transparency of water and consequently controls the seasonal dynamics of phytoplankton (autochthonous source) and lake ecology.
Maria Provenzale, Anne Ojala, Jouni Heiskanen, Kukka-Maaria Erkkilä, Ivan Mammarella, Pertti Hari, and Timo Vesala
Biogeosciences, 15, 2021–2032, https://doi.org/10.5194/bg-15-2021-2018, https://doi.org/10.5194/bg-15-2021-2018, 2018
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We extensively tested and refined a direct, high-frequency free-water CO2 measurement method to study the lake net ecosystem productivity. The method was first proposed in 2008, but neglected ever since.
With high-frequency direct methods, we can calculate the lake productivity more precisely, and parameterise its dependency on environmental variables. This helps us expand our knowledge on the carbon cycle in the water, and leads to a better integration of water bodies in carbon budgets.
Justyna J. Hampel, Mark J. McCarthy, Wayne S. Gardner, Lu Zhang, Hai Xu, Guangwei Zhu, and Silvia E. Newell
Biogeosciences, 15, 733–748, https://doi.org/10.5194/bg-15-733-2018, https://doi.org/10.5194/bg-15-733-2018, 2018
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Our paper highlights the importance of dual-nutrient management: nitrogen (N) and phosphorus (P) in lakes with cyanobacterial harmful algal blooms.
Taihu Lake (China) experiences seasonal blooms due to increased input of N and P from field runoff. The main process investigated in our study, nitrification,
is important for N removal through denitrification. We show that nitrification is less efficient during the blooms, due to competition for nutrients between
N microbes and cyanobacteria.
Martin Berggren, Marcus Klaus, Balathandayuthabani Panneer Selvam, Lena Ström, Hjalmar Laudon, Mats Jansson, and Jan Karlsson
Biogeosciences, 15, 457–470, https://doi.org/10.5194/bg-15-457-2018, https://doi.org/10.5194/bg-15-457-2018, 2018
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The quality of dissolved organic carbon (DOC), especially its color, is a defining feature of freshwater ecosystems. We found that colored DOC fractions are surprisingly resistant to natural degradation during water transit through many brown-water lakes. This is explained by the dominance of microbial processes that appear to selectively remove noncolored DOC. However, in lakes where sunlight degradation plays a relatively larger role, significant DOC bleaching occurs.
Peter Berg and Michael L. Pace
Biogeosciences, 14, 5595–5606, https://doi.org/10.5194/bg-14-5595-2017, https://doi.org/10.5194/bg-14-5595-2017, 2017
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We use the aquatic eddy covariance technique – developed first for benthic O2 flux measurements – right below the air–water interface (~ 4 cm) to determine gas exchange rates and coefficients. This use of the technique is particularly useful in studies of gas exchange and its dynamics and controls. The approach can thus help reduce the recognized problem of large uncertainties linked to gas exchange estimates in traditional aquatic ecosystem studies.
Matthew Q. Morison, Merrin L. Macrae, Richard M. Petrone, and LeeAnn Fishback
Biogeosciences, 14, 5471–5485, https://doi.org/10.5194/bg-14-5471-2017, https://doi.org/10.5194/bg-14-5471-2017, 2017
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Shallow ponds and lakes are common features in permafrost systems. We show that the chemistry of these water bodies can be dynamic, although the changes are consistent through time between ponds. This synchrony in some water chemistry appears to be related to water level variations. Because hydrological conditions can vary greatly over the course of the year and during a storm, this work underscores the importance of interpreting water samples from these systems within their hydrologic context.
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.
Ana M. Morales-Williams, Alan D. Wanamaker Jr., and John A. Downing
Biogeosciences, 14, 2865–2875, https://doi.org/10.5194/bg-14-2865-2017, https://doi.org/10.5194/bg-14-2865-2017, 2017
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Our study investigated the mechanisms sustaining cyanobacteria blooms when CO2 is depleted in lake surface waters. We found that when lake CO2 concentrations drop below those of the atmosphere, cyanobacteria switch on carbon concentrating mechanisms (CCMs), allowing them to actively take up bicarbonate. This may provide bloom-forming cyanobacteria with a competitive advantage over other algae. These results provide insight into the timing and duration of blooms in high-nutrient lakes.
Ana R. A. Soares, Ann-Kristin Bergström, Ryan A. Sponseller, Joanna M. Moberg, Reiner Giesler, Emma S. Kritzberg, Mats Jansson, and Martin Berggren
Biogeosciences, 14, 1527–1539, https://doi.org/10.5194/bg-14-1527-2017, https://doi.org/10.5194/bg-14-1527-2017, 2017
María Encina Aulló-Maestro, Peter Hunter, Evangelos Spyrakos, Pierre Mercatoris, Attila Kovács, Hajnalka Horváth, Tom Preston, Mátyás Présing, Jesús Torres Palenzuela, and Andrew Tyler
Biogeosciences, 14, 1215–1233, https://doi.org/10.5194/bg-14-1215-2017, https://doi.org/10.5194/bg-14-1215-2017, 2017
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As first study within my PhD with the general objective to improve and adapt remote sensing algorithms for the estimation of coloured dissolved organic matter (CDOM) content in lakes in a global scale, we carried out this set of measurements and experiments.
This study gives us a better understanding of sources and variability in the optical properties of CDOM in lakes and how photobleaching controls and affects them.
Pratirupa Bardhan, Syed Wajih Ahmad Naqvi, Supriya G. Karapurkar, Damodar M. Shenoy, Siby Kurian, and Hema Naik
Biogeosciences, 14, 767–779, https://doi.org/10.5194/bg-14-767-2017, https://doi.org/10.5194/bg-14-767-2017, 2017
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Although India has the third highest number of dams globally, there is a knowledge gap on the cycling of bioessential elements in such systems. This study (first of its kind) investigates the stable isotopes of nitrate and particulate organic matter in a pristine Indian reservoir. Nitrogen transformations in the anaerobic bottom waters were isotopically characterised. Overall, solar intensity, water depth and redox conditions are the major controls on the biogeochemical cycling in this system.
Bethany N. Deshpande, Sophie Crevecoeur, Alex Matveev, and Warwick F. Vincent
Biogeosciences, 13, 4411–4427, https://doi.org/10.5194/bg-13-4411-2016, https://doi.org/10.5194/bg-13-4411-2016, 2016
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Subarctic lakes are changing in size as a result of permafrost thawing, resulting in mobilization of soil materials. Our study characterizes the carbon and nutrient regime of a set of thaw lakes and their adjacent permafrost soils in a rapidly degrading landscape, showing how these materials create favorable conditions for aquatic bacterial communities. We discuss the controls over the bacterial community, and demonstrate that gain processes are not a primary control.
Marloes Groeneveld, Lars Tranvik, Sivakiruthika Natchimuthu, and Birgit Koehler
Biogeosciences, 13, 3931–3943, https://doi.org/10.5194/bg-13-3931-2016, https://doi.org/10.5194/bg-13-3931-2016, 2016
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Temporal variability in the apparent quantum yield of photochemical CDOM mineralisation in a boreal brown water lake was severalfold smaller than previously reported across different lakes. Simulated DIC photoproduction (2012–2014) averaged 2.0 ± 0.1 to 10.3 ± 0.7 g C m−2 yr−1 using the least and most reactive sample, which represented 1 to 8 % of the total mean CO2 emissions. Thus, direct CDOM photomineralisation makes only a minor contribution to mean CO2 emissions from Swedish brown water lakes.
Damien Bouffard and Marie-Elodie Perga
Biogeosciences, 13, 3573–3584, https://doi.org/10.5194/bg-13-3573-2016, https://doi.org/10.5194/bg-13-3573-2016, 2016
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This survey of an exceptional flood over Lake Geneva challenges the long-standing hypothesis that dense, particle-loaded and oxygenated rivers plunging into lakes necessarily contribute to deep-oxygen replenishment. We identified some river intrusions as hot spots for oxygen consumption, where inputs of fresh river-borne organic matter reactivate the respiration of more refractory lacustrine organic matter in a process referred to as "priming effect".
Raquel Mendonça, Sarian Kosten, Sebastian Sobek, Simone Jaqueline Cardoso, Marcos Paulo Figueiredo-Barros, Carlos Henrique Duque Estrada, and Fábio Roland
Biogeosciences, 13, 3331–3342, https://doi.org/10.5194/bg-13-3331-2016, https://doi.org/10.5194/bg-13-3331-2016, 2016
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Hydroelectric reservoirs in the tropics emit greenhouse gases but also bury carbon in their sediments. We investigated the efficiency of organic carbon (OC) burial in a large tropical reservoir, using spatially resolved measurements of sediment accumulation, and found that more than half (~ 57 %) of the OC deposited onto the sediment is buried. This high efficiency in OC burial indicates that tropical reservoirs may bury OC more efficiently than natural lakes.
Phil-Goo Kang, Myron J. Mitchell, Patrick J. McHale, Charles T. Driscoll, Shreeram Inamdar, and Ji-Hyung Park
Biogeosciences, 13, 2787–2801, https://doi.org/10.5194/bg-13-2787-2016, https://doi.org/10.5194/bg-13-2787-2016, 2016
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Lakes play important roles in controlling organic matter derived from watersheds and within-lake production. The organic matter is normally measured by elemental quantities, such as carbon(C) and nitrogen(N), because the two elements are essential for aquatic ecosystems. We observed an decrease of C, but an increase of N in organic matters in a lake. The reason of the different pattern might be that inorganic N in the lake appeared to be recycled to produce organic N due to within-lake processes.
L. Pinho, C. M. Duarte, H. Marotta, and A. Enrich-Prast
Biogeosciences, 13, 865–871, https://doi.org/10.5194/bg-13-865-2016, https://doi.org/10.5194/bg-13-865-2016, 2016
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Unlike the positive relationship reported before between partial pression of carbon dioxide and dissolved organic carbon for lake waters, we found no significant relationship in our low-latitude lakes, despite very broad ranges in both variables. The strength of this relationship declines with increasing water temperature, suggesting substantial differences in carbon cycling in warm lakes, which must be considered when upscaling limnetic carbon cycling to global scales.
S. G. Wakeham and E. A. Canuel
Biogeosciences, 13, 567–582, https://doi.org/10.5194/bg-13-567-2016, https://doi.org/10.5194/bg-13-567-2016, 2016
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Bed sediments from the Sacramento-San Joaquin River Delta (CA) were fractionated according to density and analyzed for sediment mass distribution, elemental (C and N) composition, mineral surface area, and stable carbon and radiocarbon isotope compositions of organic carbon (OC) and fatty acids to evaluate the nature of organic carbon in river sediments. These data demonstrate the complex source and age distributions within river sediments.
B. Burpee, J. E. Saros, R. M. Northington, and K. S. Simon
Biogeosciences, 13, 365–374, https://doi.org/10.5194/bg-13-365-2016, https://doi.org/10.5194/bg-13-365-2016, 2016
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This study investigates microbial nutrient limitation patterns across a region of southwest Greenland in relation to environmental factors. Using microbial enzyme activities to infer nutrient limitation patterns, we determined that most lakes are P-limited. Further, P limitation was tightly controlled by lake dissolved organic carbon (DOC) concentration.
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