Articles | Volume 17, issue 9
https://doi.org/10.5194/bg-17-2473-2020
© Author(s) 2020. 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-17-2473-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
07 May 2020
Research article |
| 07 May 2020
| 07 May 2020
The nonconservative distribution pattern of organic matter in the Rajang, a tropical river with peatland in its estuary
Zhuo-Yi Zhu
CORRESPONDING AUTHOR
State Key Laboratory of Estuarine and Coastal Research, East China Normal
University, Shanghai, 200241, China
Joanne Oakes
Centre for Coastal Biogeochemistry, School of Environment, Science and
Engineering, Southern Cross University, Lismore, NSW, 2480, Australia
Bradley Eyre
Centre for Coastal Biogeochemistry, School of Environment, Science and
Engineering, Southern Cross University, Lismore, NSW, 2480, Australia
Youyou Hao
State Key Laboratory of Estuarine and Coastal Research, East China Normal
University, Shanghai, 200241, China
Edwin Sien Aun Sia
Faculty of Engineering, Computing and
Science, Swinburne University of Technology, Jalan Simpang Tiga, Kuching, 93350, Sarawak, Malaysia
Shan Jiang
State Key Laboratory of Estuarine and Coastal Research, East China Normal
University, Shanghai, 200241, China
Moritz Müller
Faculty of Engineering, Computing and
Science, Swinburne University of Technology, Jalan Simpang Tiga, Kuching, 93350, Sarawak, Malaysia
Jing Zhang
State Key Laboratory of Estuarine and Coastal Research, East China Normal
University, Shanghai, 200241, China
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This study offered detailed information on dFe concentrations, distribution and the magnitude of yield in the Rajang River, the largest river in Malaysia. Three blackwater rivers, draining from peatlands, were also included in our study. Compared with the Rajang River, the dFe concentrations and yield from three blackwater rivers were much higher. The precipitation and agricultural activities, such as palm oil plantations, may markedly increase the concentration dFe in these tropical rivers.
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Microbial community composition and diversity in freshwater habitats are much less studied compared to marine and soil communities. This study presents the first assessment of microbial communities of the Rajang River, the longest river in Malaysia, expanding our knowledge of microbial ecology in tropical regions. Areas surrounded by oil palm plantations showed the lowest diversity and other signs of anthropogenic impacts included the presence of CFB groups as well as probable algal blooms.
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Revised manuscript not accepted
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Nutrient loads carried by large rivers and discharged into the continental shelf and coastal waters are vital to support primary production. Our knowledge of tropical river systems is fragmented with very few seasonal studies available for Southeast Asia (SEA). We present data from three sampling campaigns on the longest river in Malaysia, the Rajang river. Our results show the generalization of SEA as a nutrient hotspot might not hold true for all regions and requires further investigation.
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In this manuscript, we evaluated the submarine groundwater discharge (SGD) by three approaches and its derived nutrients in the highly stratified Krka River Estuary (KRE), Croatia based on radium isotopes. By establishing the water and nutrient budgets in the KRE surface layer, even if SGD accounted for a small portion of the total water input, nutrient fluxes through SGD were significant, especially the high N : P ratios in SGD have the notable potential to impact the ecosystem of the KRE.
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Biogeosciences, 16, 4243–4260, https://doi.org/10.5194/bg-16-4243-2019, https://doi.org/10.5194/bg-16-4243-2019, 2019
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Microbial community composition and diversity in freshwater habitats are much less studied compared to marine and soil communities. This study presents the first assessment of microbial communities of the Rajang River, the longest river in Malaysia, expanding our knowledge of microbial ecology in tropical regions. Areas surrounded by oil palm plantations showed the lowest diversity and other signs of anthropogenic impacts included the presence of CFB groups as well as probable algal blooms.
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Revised manuscript not accepted
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Nutrient loads carried by large rivers and discharged into the continental shelf and coastal waters are vital to support primary production. Our knowledge of tropical river systems is fragmented with very few seasonal studies available for Southeast Asia (SEA). We present data from three sampling campaigns on the longest river in Malaysia, the Rajang river. Our results show the generalization of SEA as a nutrient hotspot might not hold true for all regions and requires further investigation.
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Biogeosciences, 15, 6847–6865, https://doi.org/10.5194/bg-15-6847-2018, https://doi.org/10.5194/bg-15-6847-2018, 2018
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Philip M. Riekenberg, Joanne M. Oakes, and Bradley D. Eyre
Biogeosciences, 15, 2873–2889, https://doi.org/10.5194/bg-15-2873-2018, https://doi.org/10.5194/bg-15-2873-2018, 2018
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Georgina Robinson, Thomas MacTavish, Candida Savage, Gary S. Caldwell, Clifford L. W. Jones, Trevor Probyn, Bradley D. Eyre, and Selina M. Stead
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This study examined the combined effect of seawater warming and organic matter enrichment on coral reef sediment metabolism. Sediments under control conditions were net autotrophic and net calcifying. Warming shifted the sediment to net heterotrophy and net dissolution, while organic matter enrichment increased net production and net calcification. When combined, the effects of each treatment were counterbalanced and sediment metabolism did not significantly differ from control treatments.
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Jianan Liu, Jinzhou Du, Blaženka Gašparović, Milan Čanković, Enis Hrustić, Neven Cukrov, Zhuoyi Zhu, and Ruifeng Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-254, https://doi.org/10.5194/bg-2017-254, 2017
Preprint retracted
Short summary
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In this manuscript, we evaluated the submarine groundwater discharge (SGD) by three approaches and its derived nutrients in the highly stratified Krka River Estuary (KRE), Croatia based on radium isotopes. By establishing the water and nutrient budgets in the KRE surface layer, even if SGD accounted for a small portion of the total water input, nutrient fluxes through SGD were significant, especially the high N : P ratios in SGD have the notable potential to impact the ecosystem of the KRE.
Hilton B. Swan, Graham B. Jones, Elisabeth S. M. Deschaseaux, and Bradley D. Eyre
Biogeosciences, 14, 229–239, https://doi.org/10.5194/bg-14-229-2017, https://doi.org/10.5194/bg-14-229-2017, 2017
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We measured the sulfur gas dimethylsulfide (DMS) in marine air at a coral cay on the Great Barrier Reef. DMS is well known to be released from the world's oceans, but environmental evidence of coral reefs releasing DMS has not been clearly demonstrated. We showed the coral reef can sometimes release DMS to the air, which was seen as spikes above the DMS released from the ocean. The DMS from the reef supplements the DMS from the ocean to assist formation of clouds that influence local climate.
Zhuo-Yi Zhu, Ying Wu, Su-Mei Liu, Fred Wenger, Jun Hu, Jing Zhang, and Rui-Feng Zhang
Biogeosciences, 13, 975–987, https://doi.org/10.5194/bg-13-975-2016, https://doi.org/10.5194/bg-13-975-2016, 2016
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J. M. Oakes and B. D. Eyre
Biogeosciences, 11, 1927–1940, https://doi.org/10.5194/bg-11-1927-2014, https://doi.org/10.5194/bg-11-1927-2014, 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
B. D. Eyre, I. R. Santos, and D. T. Maher
Biogeosciences, 10, 2601–2615, https://doi.org/10.5194/bg-10-2601-2013, https://doi.org/10.5194/bg-10-2601-2013, 2013
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Biogeosciences, 10, 2467–2480, https://doi.org/10.5194/bg-10-2467-2013, https://doi.org/10.5194/bg-10-2467-2013, 2013
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Algal biomarkers were used to assess sea ice and pelagic algal production across the western Arctic Ocean with changing sea-ice conditions. They show three distinct areas along with a marked latitudinal gradient of sea ice over pelagic algal production in surface sediments that are reflected by the H-Print index. Our data also show that efficient grazing consumption accounted for the dramatic decrease of diatom-derived biomarkers in sediments compared to that of particulate matter.
Hanxiao Wang, Zhifei Liu, Jiaying Li, Baozhi Lin, Yulong Zhao, Xiaodong Zhang, Junyuan Cao, Jingwen Zhang, Hongzhe Song, and Wenzhuo Wang
Biogeosciences, 20, 5109–5123, https://doi.org/10.5194/bg-20-5109-2023, https://doi.org/10.5194/bg-20-5109-2023, 2023
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The sinking of zooplankton fecal pellets is a key process in the marine biological carbon pump. This study presents carbon export of four shapes of fecal pellets from two time-series sediment traps in the South China Sea. The results show that the sinking fate of fecal pellets is regulated by marine primary productivity, deep-dwelling zooplankton community, and deep-sea currents in the tropical marginal sea, thus providing a new perspective for exploring the carbon cycle in the world ocean.
Rebecca J. Chmiel, Riss M. Kell, Deepa Rao, Dawn M. Moran, Giacomo R. DiTullio, and Mak A. Saito
Biogeosciences, 20, 3997–4027, https://doi.org/10.5194/bg-20-3997-2023, https://doi.org/10.5194/bg-20-3997-2023, 2023
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Cobalt is an important micronutrient for plankton, yet it is often scarce throughout the oceans. A 2017/2018 expedition to coastal Antarctica, including regions of the Amundsen Sea and the Ross Sea, discovered lower concentrations of cobalt compared to two past expeditions in 2005 and 2006, particularly for the type of cobalt preferred as a nutrient by phytoplankton. This loss may be due to changing inputs of other nutrients, causing higher uptake of cobalt by plankton over the last decade.
Emily B. Graham, Hyun-Seob Song, Samantha Grieger, Vanessa A. Garayburu-Caruso, James C. Stegen, Kevin D. Bladon, and Allison N. Myers-Pigg
Biogeosciences, 20, 3449–3457, https://doi.org/10.5194/bg-20-3449-2023, https://doi.org/10.5194/bg-20-3449-2023, 2023
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Intensifying wildfires are increasing pyrogenic organic matter (PyOM) production and its impact on water quality. Recent work indicates that PyOM may have a greater impact on aquatic biogeochemistry than previously assumed, driven by higher bioavailability. We provide a full assessment of the potential bioavailability of PyOM across its chemical spectrum. We indicate that PyOM can be actively transformed within the river corridor and, therefore, may be a growing source of riverine C emissions.
Nora Richter, Ellen C. Hopmans, Danica Mitrović, Pedro M. Raposeiro, Vítor Gonçalves, Ana C. Costa, Linda A. Amaral-Zettler, Laura Villanueva, and Darci Rush
Biogeosciences, 20, 2065–2098, https://doi.org/10.5194/bg-20-2065-2023, https://doi.org/10.5194/bg-20-2065-2023, 2023
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Bacteriohopanepolyols (BHPs) are a diverse class of lipids produced by bacteria across a wide range of environments. This study characterizes the diversity of BHPs in lakes and coastal lagoons in the Azores Archipelago, as well as a co-culture enriched for methanotrophs. We highlight the potential of BHPs as taxonomic markers for bacteria associated with certain ecological niches, which can be preserved in sedimentary records.
Andrea Scheibe, Carlos A. Sierra, and Marie Spohn
Biogeosciences, 20, 827–838, https://doi.org/10.5194/bg-20-827-2023, https://doi.org/10.5194/bg-20-827-2023, 2023
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We explored carbon cycling in soils in three climate zones in Chile down to a depth of 6 m, using carbon isotopes. Our results show that microbial activity several meters below the soil surface is mostly fueled by recently fixed carbon and that strong decomposition of soil organic matter only occurs in the upper decimeters of the soils. The study shows that different layers of the critical zone are tightly connected and that processes in the deep soil depend on recently fixed carbon.
Melissa Sophia Schwab, Hannah Gies, Chantal Valérie Freymond, Maarten Lupker, Negar Haghipour, and Timothy Ian Eglinton
Biogeosciences, 19, 5591–5616, https://doi.org/10.5194/bg-19-5591-2022, https://doi.org/10.5194/bg-19-5591-2022, 2022
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The majority of river studies focus on headwater or floodplain systems, while often neglecting intermediate river segments. Our study on the subalpine Sihl River bridges the gap between streams and lowlands and demonstrates that moderately steep river segments are areas of significant instream alterations, modulating the export of organic carbon over short distances.
Lisa Noll, Shasha Zhang, Qing Zheng, Yuntao Hu, Florian Hofhansl, and Wolfgang Wanek
Biogeosciences, 19, 5419–5433, https://doi.org/10.5194/bg-19-5419-2022, https://doi.org/10.5194/bg-19-5419-2022, 2022
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Cleavage of proteins to smaller nitrogen compounds allows microorganisms and plants to exploit the largest nitrogen reservoir in soils and is considered the bottleneck in soil organic nitrogen cycling. Results from soils covering a European transect show that protein turnover is constrained by soil geochemistry, shifts in climate and associated alterations in soil weathering and should be considered as a driver of soil nitrogen availability with repercussions on carbon cycle processes.
Muhammed Fatih Sert, Helge Niemann, Eoghan P. Reeves, Mats A. Granskog, Kevin P. Hand, Timo Kekäläinen, Janne Jänis, Pamela E. Rossel, Bénédicte Ferré, Anna Silyakova, and Friederike Gründger
Biogeosciences, 19, 2101–2120, https://doi.org/10.5194/bg-19-2101-2022, https://doi.org/10.5194/bg-19-2101-2022, 2022
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We investigate organic matter composition in the Arctic Ocean water column. We collected seawater samples from sea ice to deep waters at six vertical profiles near an active hydrothermal vent and its plume. In comparison to seawater, we found that the organic matter in waters directly affected by the hydrothermal plume had different chemical composition. We suggest that hydrothermal processes may influence the organic matter distribution in the deep ocean.
Charlotte Haugk, Loeka L. Jongejans, Kai Mangelsdorf, Matthias Fuchs, Olga Ogneva, Juri Palmtag, Gesine Mollenhauer, Paul J. Mann, P. Paul Overduin, Guido Grosse, Tina Sanders, Robyn E. Tuerena, Lutz Schirrmeister, Sebastian Wetterich, Alexander Kizyakov, Cornelia Karger, and Jens Strauss
Biogeosciences, 19, 2079–2094, https://doi.org/10.5194/bg-19-2079-2022, https://doi.org/10.5194/bg-19-2079-2022, 2022
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Buried animal and plant remains (carbon) from the last ice age were freeze-locked in permafrost. At an extremely fast eroding permafrost cliff in the Lena Delta (Siberia), we found this formerly frozen carbon well preserved. Our results show that ongoing degradation releases substantial amounts of this carbon, making it available for future carbon emissions. This mobilisation at the studied cliff and also similarly eroding sites bear the potential to affect rivers and oceans negatively.
Aleksandar I. Goranov, Andrew S. Wozniak, Kyle W. Bostick, Andrew R. Zimmerman, Siddhartha Mitra, and Patrick G. Hatcher
Biogeosciences, 19, 1491–1514, https://doi.org/10.5194/bg-19-1491-2022, https://doi.org/10.5194/bg-19-1491-2022, 2022
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Wildfire-derived molecules are ubiquitous in the aquatic environment, but their biological fate remains understudied. We have evaluated the compositional changes that occur to wildfire-derived molecules after incubation with soil microbes. We observe a significant degradation but also a production of numerous new labile molecules. Our results indicate that wildfire-derived molecules can be broken down and the carbon and nitrogen therein can be incorporated into microbial food webs.
Edgart Flores, Sebastian I. Cantarero, Paula Ruiz-Fernández, Nadia Dildar, Matthias Zabel, Osvaldo Ulloa, and Julio Sepúlveda
Biogeosciences, 19, 1395–1420, https://doi.org/10.5194/bg-19-1395-2022, https://doi.org/10.5194/bg-19-1395-2022, 2022
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In this study, we investigate the chemical diversity and abundance of microbial lipids as markers of organic matter sources in the deepest points of the Atacama Trench sediments and compare them to similar lipid stocks in shallower surface sediments and in the overlying water column. We evaluate possible organic matter provenance and some potential chemical adaptations of the in situ microbial community to the extreme conditions of high hydrostatic pressure in hadal realm.
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
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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).
Zoë R. van Kemenade, Laura Villanueva, Ellen C. Hopmans, Peter Kraal, Harry J. Witte, Jaap S. Sinninghe Damsté, and Darci Rush
Biogeosciences, 19, 201–221, https://doi.org/10.5194/bg-19-201-2022, https://doi.org/10.5194/bg-19-201-2022, 2022
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Anaerobic ammonium oxidation (anammox) is an important nitrogen-removal process in the ocean. We assess the distribution of bacteriohopanetetrol-x (BHT-x), used to trace past anammox, along a redox gradient in the water column of the Benguela upwelling system. BHT-x / BHT ratios of >0.18 correspond to the presence of living anammox bacteria and oxygen levels <50 μmol L−1. This allows for a more robust application of BHT-x to trace past marine anammox and deoxygenation in dynamic marine systems.
Jia-Jang Hung, Ching-Han Tung, Zong-Ying Lin, Yuh-ling Lee Chen, Shao-Hung Peng, Yen-Huei Lin, and Li-Shan Tsai
Biogeosciences, 18, 5141–5162, https://doi.org/10.5194/bg-18-5141-2021, https://doi.org/10.5194/bg-18-5141-2021, 2021
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We report measured active and passive fluxes and their controlling mechanisms in the northern South China Sea (NSCS). The total fluxes were higher than most reports in open oceans, indicating the significance of NSCS in atmospheric CO2 uptake and in storing that CO2 in the ocean’s interior. Winter cooling and extreme events enhanced nutrient availability and elevated fluxes. Global warming may have profound impacts on reducing ocean’s uptake and storage of CO2 in subtropical–tropical oceans.
Jens Daniel Müller, Bernd Schneider, Ulf Gräwe, Peer Fietzek, Marcus Bo Wallin, Anna Rutgersson, Norbert Wasmund, Siegfried Krüger, and Gregor Rehder
Biogeosciences, 18, 4889–4917, https://doi.org/10.5194/bg-18-4889-2021, https://doi.org/10.5194/bg-18-4889-2021, 2021
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Based on profiling pCO2 measurements from a field campaign, we quantify the biomass production of a cyanobacteria bloom in the Baltic Sea, the export of which would foster deep water deoxygenation. We further demonstrate how this biomass production can be accurately reconstructed from long-term surface measurements made on cargo vessels in combination with modelled temperature profiles. This approach enables a better understanding of a severe concern for the Baltic’s good environmental status.
Alexander Braun, Marina Spona-Friedl, Maria Avramov, Martin Elsner, Federico Baltar, Thomas Reinthaler, Gerhard J. Herndl, and Christian Griebler
Biogeosciences, 18, 3689–3700, https://doi.org/10.5194/bg-18-3689-2021, https://doi.org/10.5194/bg-18-3689-2021, 2021
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It is known that CO2 fixation by photoautotrophic organisms is the major sink from the atmosphere. While biologists are aware that CO2 fixation also occurs in heterotrophic organisms, this route of inorganic carbon, and its quantitative role, is hardly recognized in biogeochemistry. We demonstrate that a considerable amount of CO2 is fixed annually through anaplerotic reactions in heterotrophic organisms, and a significant quantity of inorganic carbon is temporally sequestered in biomass.
Jonathan H. Raberg, David J. Harning, Sarah E. Crump, Greg de Wet, Aria Blumm, Sebastian Kopf, Áslaug Geirsdóttir, Gifford H. Miller, and Julio Sepúlveda
Biogeosciences, 18, 3579–3603, https://doi.org/10.5194/bg-18-3579-2021, https://doi.org/10.5194/bg-18-3579-2021, 2021
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BrGDGT lipids are a proxy for temperature in lake sediments, but other parameters like pH can influence them, and seasonality can affect the temperatures they record. We find a warm-season bias at 43 new high-latitude sites. We also present a new method that deconvolves the effects of temperature, pH, and conductivity and generate global calibrations for these variables. Our study provides new paleoclimate tools, insight into brGDGTs at the biochemical level, and a new method for future study.
Charlotte L. Spencer-Jones, Erin L. McClymont, Nicole J. Bale, Ellen C. Hopmans, Stefan Schouten, Juliane Müller, E. Povl Abrahamsen, Claire Allen, Torsten Bickert, Claus-Dieter Hillenbrand, Elaine Mawbey, Victoria Peck, Aleksandra Svalova, and James A. Smith
Biogeosciences, 18, 3485–3504, https://doi.org/10.5194/bg-18-3485-2021, https://doi.org/10.5194/bg-18-3485-2021, 2021
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Long-term ocean temperature records are needed to fully understand the impact of West Antarctic Ice Sheet collapse. Glycerol dialkyl glycerol tetraethers (GDGTs) are powerful tools for reconstructing ocean temperature but can be difficult to apply to the Southern Ocean. Our results show active GDGT synthesis in relatively warm depths of the ocean. This research improves the application of GDGT palaeoceanographic proxies in the Southern Ocean.
Alec W. Armstrong, Leanne Powers, and Michael Gonsior
Biogeosciences, 18, 3367–3390, https://doi.org/10.5194/bg-18-3367-2021, https://doi.org/10.5194/bg-18-3367-2021, 2021
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Living things decay into organic matter, which can dissolve into water (like tea brewing). Tea receives its color by absorbing light. Similarly, this material absorbs light, which can then cause chemical reactions that change it. By measuring changes in these optical properties, we found that materials from some places are more sensitive to light than others. Comparing sensitivity to light helps us understand where these materials come from and what happens as they move through water.
Ben J. Fisher, Johan C. Faust, Oliver W. Moore, Caroline L. Peacock, and Christian März
Biogeosciences, 18, 3409–3419, https://doi.org/10.5194/bg-18-3409-2021, https://doi.org/10.5194/bg-18-3409-2021, 2021
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Organic carbon can be protected from microbial degradation in marine sediments through association with iron minerals on 1000-year timescales. Despite the importance of this carbon sink, our spatial and temporal understanding of iron-bound organic carbon interactions globally is poor. Here we show that caution must be applied when comparing quantification of iron-bound organic carbon extracted by different methods as the extraction strength and method specificity can be highly variable.
Mark A. Stevenson, Suzanne McGowan, Emma J. Pearson, George E. A. Swann, Melanie J. Leng, Vivienne J. Jones, Joseph J. Bailey, Xianyu Huang, and Erika Whiteford
Biogeosciences, 18, 2465–2485, https://doi.org/10.5194/bg-18-2465-2021, https://doi.org/10.5194/bg-18-2465-2021, 2021
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We link detailed stable isotope and biomarker analyses from the catchments of three Arctic upland lakes on Disko Island (West Greenland) to a recent dated sediment core to understand how carbon cycling has changed over the past ~500 years. We find that the carbon deposited in sediments in these upland lakes is predominately sourced from in-lake production due to the catchment's limited terrestrial vegetation and elevation and that recent increases in algal production link with climate change.
Nadine T. Smit, Laura Villanueva, Darci Rush, Fausto Grassa, Caitlyn R. Witkowski, Mira Holzheimer, Adriaan J. Minnaard, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 18, 1463–1479, https://doi.org/10.5194/bg-18-1463-2021, https://doi.org/10.5194/bg-18-1463-2021, 2021
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Soils from an everlasting fire (gas seep) in Sicily, Italy, reveal high relative abundances of novel uncultivated mycobacteria and unique 13C-depleted mycocerosic acids (multi-methyl branched fatty acids) close to the main gas seep. Our results imply that mycocerosic acids in combination with their depleted δ13C values offer a new biomarker tool to study the role of soil mycobacteria as hydrocarbon consumers in the modern and past global carbon cycle.
Marcus P. S. Badger
Biogeosciences, 18, 1149–1160, https://doi.org/10.5194/bg-18-1149-2021, https://doi.org/10.5194/bg-18-1149-2021, 2021
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Reconstructing ancient atmospheric CO2 is an important aim of palaeoclimate science in order to understand the Earth's climate system. One method, the alkenone proxy based on molecular fossils of coccolithophores, has been recently shown to be ineffective at low-to-moderate CO2 levels. In this paper I show that this is likely due to changes in the biogeochemistry of the coccolithophores when there is low carbon availability, but for much of the Cenozoic the alkenone proxy should have utility.
Loes G. J. van Bree, Francien Peterse, Allix J. Baxter, Wannes De Crop, Sigrid van Grinsven, Laura Villanueva, Dirk Verschuren, and Jaap S. Sinninghe Damsté
Biogeosciences, 17, 5443–5463, https://doi.org/10.5194/bg-17-5443-2020, https://doi.org/10.5194/bg-17-5443-2020, 2020
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Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are used as a paleothermometer based on their temperature dependence in global soils, but aquatic production complicates their use in lakes. BrGDGTs in the water column of Lake Chala, East Africa, respond to oxygen conditions and mixing. Changes in their signal can be linked to bacterial community composition rather than membrane adaptation to changing conditions. Their integrated signal in the sediment reflects mean air temperature.
Alexandra N. Loginova, Andrew W. Dale, Frédéric A. C. Le Moigne, Sören Thomsen, Stefan Sommer, David Clemens, Klaus Wallmann, and Anja Engel
Biogeosciences, 17, 4663–4679, https://doi.org/10.5194/bg-17-4663-2020, https://doi.org/10.5194/bg-17-4663-2020, 2020
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We measured dissolved organic carbon (DOC), nitrogen (DON) and matter (DOM) optical properties in pore waters and near-bottom waters of the eastern tropical South Pacific off Peru. The difference between diffusion-driven and net fluxes of DOC and DON and qualitative changes in DOM optical properties suggested active microbial utilisation of the released DOM at the sediment–water interface. Our results suggest that the sediment release of DOM contributes to microbial processes in the area.
Gerard J. M. Versteegh, Alexander J. P. Houben, and Karin A. F. Zonneveld
Biogeosciences, 17, 3545–3561, https://doi.org/10.5194/bg-17-3545-2020, https://doi.org/10.5194/bg-17-3545-2020, 2020
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Anoxic sediments mostly contain much more organic matter than oxic ones, and therefore organic matter in anoxic settings is often considered to be preserved better than in oxic settings. However, through the analysis of the same fossil dinoflagellate cyst species from both oxic and anoxic settings, we show that at a molecular level the preservation in the oxic sediments may be better since in the anoxic setting the cyst macromolecule has been altered by postdepositional modification.
Jingjing Guo, Miriam Glendell, Jeroen Meersmans, Frédérique Kirkels, Jack J. Middelburg, and Francien Peterse
Biogeosciences, 17, 3183–3201, https://doi.org/10.5194/bg-17-3183-2020, https://doi.org/10.5194/bg-17-3183-2020, 2020
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The fluxes of soil organic carbon (OC) transport from land to sea are poorly constrained, mostly due to the lack of a specific tracer for soil OC. Here we evaluate the use of specific molecules derived from soil bacteria as a tracer for soil OC in a small river catchment. We find that the initial soil signal is lost upon entering the aquatic environment. However, the local environmental history of the catchment is reflected by these molecules in the lake sediments that act as their sink.
Wenjie Xiao, Yasong Wang, Yongsheng Liu, Xi Zhang, Linlin Shi, and Yunping Xu
Biogeosciences, 17, 2135–2148, https://doi.org/10.5194/bg-17-2135-2020, https://doi.org/10.5194/bg-17-2135-2020, 2020
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The hadal zone (6–11 km depth) is the least explored habitat on Earth. We studied microbial branched glycerol dialkyl glycerol tetraethers (brGDGTs) in the Challenger Deep, Mariana Trench. One unique feature is the strong predominance of 6-methyl brGDGT, which likely reflects an adaption of brGDGT-producing bacteria to alkaline seawater and low temperature. BrGDGTs, with elemental and isotopic data, suggest an autochthonous product for brGDGT. A new approach is proposed for brGDGT sourcing.
Yuge Bai, Edisson Subdiaga, Stefan B. Haderlein, Heike Knicker, and Andreas Kappler
Biogeosciences, 17, 683–698, https://doi.org/10.5194/bg-17-683-2020, https://doi.org/10.5194/bg-17-683-2020, 2020
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Biogeochemical processes of SOM are key for greenhouse gas emission and water quality. We extracted SOM by water or by NaOH–HCl under oxic–anoxic conditions. Chemical and anoxic extractions lead to higher SOM electron exchange capacities, resulting in stimulation of microbial Fe(III) reduction. Therefore, aqueous pH-neutral SOM extracts should be used to reflect environmental SOM redox processes, and artifacts of chemical extractions need to be considered when evaluating SOM redox processes.
Yan Shen, Volker Thiel, Pablo Suarez-Gonzalez, Sebastiaan W. Rampen, and Joachim Reitner
Biogeosciences, 17, 649–666, https://doi.org/10.5194/bg-17-649-2020, https://doi.org/10.5194/bg-17-649-2020, 2020
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Today, sterols are widespread in plants, animals, and fungi but are almost absent in the oldest rocks. Microbial mats, representing the earliest complex ecosystems on Earth, were omnipresent in Precambrian marine environments and may have degraded the sterols at that time. Here we analyze the distribution of sterols through a microbial mat. This provides insight into how variations in biological and nonbiological factors affect the preservation of sterols in modern and ancient microbial mats.
Sarah Coffinet, Travis B. Meador, Lukas Mühlena, Kevin W. Becker, Jan Schröder, Qing-Zeng Zhu, Julius S. Lipp, Verena B. Heuer, Matthew P. Crump, and Kai-Uwe Hinrichs
Biogeosciences, 17, 317–330, https://doi.org/10.5194/bg-17-317-2020, https://doi.org/10.5194/bg-17-317-2020, 2020
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This study deals with two membrane lipids called BDGTs and PDGTs. Membrane lipids are molecules forming the cell envelope of all organisms. Different organisms produce different lipids thus they can be used to detect the presence of specific organisms in the environment. We analyzed the structure of these new lipids and looked for potential producers. We found that they are likely made by microbes emitting methane below the sediment surface and could be used to track these specific microbes.
Ying Wu, Kun Zhu, Jing Zhang, Moritz Müller, Shan Jiang, Aazani Mujahid, Mohd Fakharuddin Muhamad, and Edwin Sien Aun Sia
Biogeosciences, 16, 4517–4533, https://doi.org/10.5194/bg-16-4517-2019, https://doi.org/10.5194/bg-16-4517-2019, 2019
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Our understanding of terrestrial organic matter (TOM) in tropical peat-draining rivers remains limited, especially in Southeast Asia. We explored the characteristics of TOM via bulk parameters and lignin phenols of sediment in Malaysia. This showed that the most important plant source of the organic matter in these rivers is woody angiosperm C3 plants with limited diagenetic alteration. This slower degradation of TOM may be a link to higher total nitrogen content, especially for the small river.
Caitlyn R. Witkowski, Sylvain Agostini, Ben P. Harvey, Marcel T. J. van der Meer, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 16, 4451–4461, https://doi.org/10.5194/bg-16-4451-2019, https://doi.org/10.5194/bg-16-4451-2019, 2019
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Carbon dioxide concentrations (pCO2) in the atmosphere play an integral role in Earth system dynamics, especially climate. Past climates help us understand future ones, but reconstructing pCO2 over the geologic record remains a challenge. This research demonstrates new approaches for exploring past pCO2 via the carbon isotope fractionation in general algal lipids, which we test over a high CO2 gradient from a naturally occurring CO2 seep.
Yongli Zhou, Patrick Martin, and Moritz Müller
Biogeosciences, 16, 2733–2749, https://doi.org/10.5194/bg-16-2733-2019, https://doi.org/10.5194/bg-16-2733-2019, 2019
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We found that peatlands in coastal Sarawak, Borneo, export extremely humified organic matter, which dominates the riverine organic matter pool and conservatively mixes with seawater, while the freshly produced fraction is low and stable in concentration at all salinities. We estimated that terrigenous fractions, which showed high photolability, still account for 20 % of the coastal dissolved organic carbon pool, implying the importance of peat-derived organic matter in the coastal carbon cycle.
Kristin Doering, Claudia Ehlert, Philippe Martinez, Martin Frank, and Ralph Schneider
Biogeosciences, 16, 2163–2180, https://doi.org/10.5194/bg-16-2163-2019, https://doi.org/10.5194/bg-16-2163-2019, 2019
Alexandra N. Loginova, Sören Thomsen, Marcus Dengler, Jan Lüdke, and Anja Engel
Biogeosciences, 16, 2033–2047, https://doi.org/10.5194/bg-16-2033-2019, https://doi.org/10.5194/bg-16-2033-2019, 2019
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High primary production in the Peruvian upwelling system is followed by rapid heterotrophic utilization of organic matter and supports the formation of one of the most intense oxygen minimum zones (OMZs) in the world. Here, we estimated vertical fluxes of oxygen and dissolved organic matter (DOM) from the surface to the OMZ. Our results suggest that DOM remineralization substantially reduces oxygen concentration in the upper water column and controls the shape of the upper oxycline.
Carolina Cisternas-Novoa, Frédéric A. C. Le Moigne, and Anja Engel
Biogeosciences, 16, 927–947, https://doi.org/10.5194/bg-16-927-2019, https://doi.org/10.5194/bg-16-927-2019, 2019
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We investigate the composition and vertical fluxes of POM in two deep basins of the Baltic Sea (GB: Gotland Basin and LD: Landsort Deep). The two basins showed different O2 regimes resulting from the intrusion of oxygen-rich water from the North Sea that ventilated the deep waters in GB, but not in LD.
In GB, O2 intrusions lead to a high abundance of manganese oxides that aggregate with POM, altering its composition and vertical flux and contributing to a higher POC transfer efficiency in GB.
Marina Zamanillo, Eva Ortega-Retuerta, Sdena Nunes, Pablo Rodríguez-Ros, Manuel Dall'Osto, Marta Estrada, Maria Montserrat Sala, and Rafel Simó
Biogeosciences, 16, 733–749, https://doi.org/10.5194/bg-16-733-2019, https://doi.org/10.5194/bg-16-733-2019, 2019
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Many marine microorganisms produce polysaccharide-rich transparent exopolymer particles (TEPs) for rather unknown reasons but with important consequences for the ocean carbon cycle, sea–air gas exchange and formation of organic aerosols. Here we compare surface–ocean distributions of TEPs and physical, chemical and biological variables along a N–S transect in the Atlantic Ocean. Our data suggest that phytoplankton and not bacteria are the main TEP producers, and solar radiation acts as a sink.
Michael Philben, Sara Butler, Sharon A. Billings, Ronald Benner, Kate A. Edwards, and Susan E. Ziegler
Biogeosciences, 15, 6731–6746, https://doi.org/10.5194/bg-15-6731-2018, https://doi.org/10.5194/bg-15-6731-2018, 2018
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We explored the relationship between chemical composition and the temperature sensitivity of moss decomposition using 959-day lab incubations. Mass loss was low despite the predominance of carbohydrates, indicating the persistence of labile C. Scanning electron microscopy revealed little change in the moss cell-wall structure. These results suggest that the moss cell-wall matrix protects labile C from decomposition, contributing to the globally important stocks of moss-derived C.
Yinghui Wang, Robert G. M. Spencer, David C. Podgorski, Anne M. Kellerman, Harunur Rashid, Phoebe Zito, Wenjie Xiao, Dandan Wei, Yuanhe Yang, and Yunping Xu
Biogeosciences, 15, 6637–6648, https://doi.org/10.5194/bg-15-6637-2018, https://doi.org/10.5194/bg-15-6637-2018, 2018
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With global warming, thawing of permafrost releases dissolved organic matter (DOM) into streams. By analyzing DOM along an alpine stream on the Qinghai–Tibet Plateau, we found DOM was mainly from the active layer, but with deepening of the active layer, the contribution of the deep permafrost layer increased, causing a change in the chemical composition of DOM. From the head- to downstream, DOM is undergoing rapid degradation, but some components are persistent and can be transported downstream.
Sergio Balzano, Julie Lattaud, Laura Villanueva, Sebastiaan W. Rampen, Corina P. D. Brussaard, Judith van Bleijswijk, Nicole Bale, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 15, 5951–5968, https://doi.org/10.5194/bg-15-5951-2018, https://doi.org/10.5194/bg-15-5951-2018, 2018
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We tried to identify the microbes which biosynthesize a class of lipids widespread in seawater, the long chain alkyl diols (LCDs). We could not find any microorganism likely involved in the production of LCDs. The amounts of LCDs found are too high to be produced by living organisms and are likely to be part of the refractory organic matter persisting for long periods in the water column.
Julie Lattaud, Frédérique Kirkels, Francien Peterse, Chantal V. Freymond, Timothy I. Eglinton, Jens Hefter, Gesine Mollenhauer, Sergio Balzano, Laura Villanueva, Marcel T. J. van der Meer, Ellen C. Hopmans, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 15, 4147–4161, https://doi.org/10.5194/bg-15-4147-2018, https://doi.org/10.5194/bg-15-4147-2018, 2018
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Long-chain diols (LCDs) are biomarkers that occur widespread in marine environments and also in lakes and rivers. In this study, we looked at the distribution of LCDs in three river systems (Godavari, Danube, and Rhine) in relation to season, precipitation, and temperature. We found out that the LCDs are likely being produced in calm areas of the river systems and that marine LCDs have a different distribution than riverine LCDs.
Marcel Bliedtner, Imke K. Schäfer, Roland Zech, and Hans von Suchodoletz
Biogeosciences, 15, 3927–3936, https://doi.org/10.5194/bg-15-3927-2018, https://doi.org/10.5194/bg-15-3927-2018, 2018
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In this study, we systematically analyze leaf wax derived n-alkane patterns in eastern Georgia to test their potential for paleoenvironmental reconstructions in the semi-humid to semi-arid central southern Caucasus region. We investigated the influence of vegetation types on the leaf wax signal in modern plants and topsoil material. Our results show distinct and systematic differences in the n-alkane patterns between vegetation types and prove their potential for vegetation reconstructions.
Mathieu Rembauville, Stéphane Blain, Clara Manno, Geraint Tarling, Anu Thompson, George Wolff, and Ian Salter
Biogeosciences, 15, 3071–3084, https://doi.org/10.5194/bg-15-3071-2018, https://doi.org/10.5194/bg-15-3071-2018, 2018
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Sinking phytoplankton from the surface ocean provide the principal energy source to deep-ocean ecosystems. Our aim was to understand how different phytoplankton communities impact the chemical nature of this sinking material. We show certain types of phytoplankton can preferentially export energy-rich storage compounds to the seafloor. Any climate-driven effects on phytoplankton community structure could thus impact remote deep-ocean ecosystems thousands of kilometres beneath the surface.
Xiaocong Wei, Xiangwen Deng, Wenhua Xiang, Pifeng Lei, Shuai Ouyang, Hongfang Wen, and Liang Chen
Biogeosciences, 15, 2991–3002, https://doi.org/10.5194/bg-15-2991-2018, https://doi.org/10.5194/bg-15-2991-2018, 2018
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Karst is a kind of typical calcium-rich environment, which is widely distributed. We measured the Ca2+ content of 41 plant species, as well as soil total Ca2+ and exchange Ca2+. We found out that different plants have different ways to high Ca2+ adaptation. According to the different high Ca2+ adaptation of the 17 dominant species, we divided them into 3 categories: Ca-indifferent plants, high-Ca plants and low-Ca plants. Our results can provide a theoretical basis for vegetation restoration.
Janina G. Stapel, Georg Schwamborn, Lutz Schirrmeister, Brian Horsfield, and Kai Mangelsdorf
Biogeosciences, 15, 1969–1985, https://doi.org/10.5194/bg-15-1969-2018, https://doi.org/10.5194/bg-15-1969-2018, 2018
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Climate warming in the Arctic results in thawing of permafrost deposits. This promotes the accessibility of freeze-locked old organic matter (OM) accumulated during the past. Characterizing OM of different depositional ages, we were able to show that OM from last glacial Yedoma deposits possess the highest potential to provide organic substrates such as acetate for microbial greenhouse gas production and therefore to accelerate the carbon–climate feedback cycle during ongoing global warming.
Changchun Huang, Quanliang Jiang, Ling Yao, Hao Yang, Chen Lin, Tao Huang, A-Xing Zhu, and Yimin Zhang
Biogeosciences, 15, 1827–1841, https://doi.org/10.5194/bg-15-1827-2018, https://doi.org/10.5194/bg-15-1827-2018, 2018
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The latitudinal dependency of POC / PON in ocean and inland water is significant, regulated by trophic state and climate, etc. factors. POC / PON significantly increased from coastal water (6.89 ± 2.38) to open ocean (7.59 ± 4.22) with the increasing rate of 0.0024 / km. The re-examination of the global relationship between, and variations in, POC and PON could be important for the global and regional coupling between the carbon and nitrogen cycles in the ocean and freshwater.
Nicole J. Bale, Tracy A. Villareal, Ellen C. Hopmans, Corina P. D. Brussaard, Marc Besseling, Denise Dorhout, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 15, 1229–1241, https://doi.org/10.5194/bg-15-1229-2018, https://doi.org/10.5194/bg-15-1229-2018, 2018
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Associations between diatoms and N-fixing cyanobacteria (diatom–diazotroph associations, DDAs) play an important role in the N cycle of the tropical North Atlantic. Heterocysts are the site of N fixation and contain unique glycolipids. We measured these glycolipids in the water column and surface sediment from the tropical North Atlantic. We found a significant correlation between the concentration of glycolipid and of DDAs, strengthening their application as biomarkers.
Laurent Jeanneau, Richard Rowland, and Shreeram Inamdar
Biogeosciences, 15, 973–985, https://doi.org/10.5194/bg-15-973-2018, https://doi.org/10.5194/bg-15-973-2018, 2018
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The source of particulate organic matter in headwaters during storm events remains an open question. We use the molecular composition of organic matter sampled during four spring–summer storms and compare it to potential sources. We identify litter, streambed and vicinal soils as the main sources of particulate organic matter. Their proportions depend on (i) the size of the catchment and (ii) the rain event.
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Short summary
Samples were collected in August 2016 in the Rajang River and its estuary, with tropical forest in the river basin and peatland in the estuary. Organic matter composition was influenced by transportation in the river basin, whereas peatland added clear biodegraded parts to the fluvial organic matter, which implies modification of the initial lability and/or starting points in the subsequent degradation and alternation processes after the organic matter enters the sea.
Samples were collected in August 2016 in the Rajang River and its estuary, with tropical forest...
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