Articles | Volume 18, issue 15
https://doi.org/10.5194/bg-18-4491-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-18-4491-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
02 Aug 2021
Research article |
| 02 Aug 2021
| 02 Aug 2021
Stable isotope ratios in seawater nitrate reflect the influence of Pacific water along the northwest Atlantic margin
Department of Earth and Environmental Sciences, Dalhousie University,
Halifax, NS, B3H 4R2, Canada
Samuel H. Davin
Geotop Research Centre, Université du Québec à
Montréal, Montréal, QC, H3C 3P8, Canada
Nadine Lehmann
Department of Oceanography, Dalhousie University, Halifax, NS, B3H
4R2, Canada
Carolyn Buchwald
Department of Oceanography, Dalhousie University, Halifax, NS, B3H
4R2, Canada
Evan N. Edinger
Department of Geography, Department of Biology, and Department of
Earth Sciences, Memorial University of Newfoundland, St. John's, NL, A1B
3X9, Canada
Moritz F. Lehmann
Department of Environmental Sciences, University of Basel, Basel,
4056, Switzerland
Markus Kienast
Department of Oceanography, Dalhousie University, Halifax, NS, B3H
4R2, Canada
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Kim A. P. Faassen, Jordi Vilà-Guerau de Arellano, Raquel González-Armas, Bert G. Heusinkveld, Ivan Mammarella, Wouter Peters, and Ingrid T. Luijkx
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Ingrid Chanca, Ingeborg Levin, Susan Trumbore, Kita Macario, Jost Lavric, Carlos Alberto Quesada, Alessandro Carioca de Araújo, Cléo Quaresma Dias Júnior, Hella van Asperen, Samuel Hammer, and Carlos Sierra
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Assessing the net carbon (C) budget of the Amazon entails considering the magnitude and timing of C absorption and losses through respiration (transit time of C). Radiocarbon-based estimates of the transit time of C in the Amazon Tall Tower Observatory (ATTO) suggest a doubling of the transit time from 6 ± 2 years and 18 ± 5 years (October 2019 and December 2021, respectively). This variability indicates that only a fraction of newly fixed C can be stored for decades or longer.
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Alessandro Zanchetta, Linda M. J. Kooijmans, Steven van Heuven, Andrea Scifo, Hubertus A. Scheeren, Ivan Mammarella, Ute Karstens, Jin Ma, Maarten Krol, and Huilin Chen
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Joel T. Bostic, David M. Nelson, and Keith N. Eshleman
Biogeosciences, 20, 2485–2498, https://doi.org/10.5194/bg-20-2485-2023, https://doi.org/10.5194/bg-20-2485-2023, 2023
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Land-use changes can affect water quality. We used tracers of pollution sources and water flow paths to show that an urban watershed exports variable sources during storm events relative to a less developed watershed. Our results imply that changing precipitation patterns combined with increasing urbanization may alter sources of pollution in the future.
Robin Havas, Christophe Thomazo, Miguel Iniesto, Didier Jézéquel, David Moreira, Rosaluz Tavera, Jeanne Caumartin, Elodie Muller, Purificación López-García, and Karim Benzerara
Biogeosciences, 20, 2405–2424, https://doi.org/10.5194/bg-20-2405-2023, https://doi.org/10.5194/bg-20-2405-2023, 2023
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Dissolved organic carbon (DOC) is a reservoir of prime importance in the C cycle of both continental and marine systems. It has also been suggested to influence the past Earth climate but is still poorly characterized in ancient-Earth-like environments. In this paper we show how DOC analyses from modern redox-stratified lakes can evidence specific metabolic reactions and environmental factors and how these can help us to interpret the C cycle of specific periods in the Earth's past.
Robin Havas, Christophe Thomazo, Miguel Iniesto, Didier Jézéquel, David Moreira, Rosaluz Tavera, Jeanne Caumartin, Elodie Muller, Purificación López-García, and Karim Benzerara
Biogeosciences, 20, 2347–2367, https://doi.org/10.5194/bg-20-2347-2023, https://doi.org/10.5194/bg-20-2347-2023, 2023
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We describe the C cycle of four modern stratified water bodies from Mexico, a necessary step to better understand the C cycle of primitive-Earth-like environments, which were dominated by these kinds of conditions. We highlight the importance of local external factors on the C cycle of these systems. Notably, they influence the sensitivity of the carbonate record to environmental changes. We also show the strong C-cycle variability among these lakes and their organic C sediment record.
Yifan Ma, Kuanbo Zhou, Weifang Chen, Junhui Chen, Jin-Yu Terence Yang, and Minhan Dai
Biogeosciences, 20, 2013–2030, https://doi.org/10.5194/bg-20-2013-2023, https://doi.org/10.5194/bg-20-2013-2023, 2023
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We distinguished particulate organic carbon (POC) export fluxes out of the nutrient-depleted layer (NDL) and the euphotic zone. The amount of POC export flux at the NDL base suggests that the NDL could be a hotspot of particle export. The substantial POC export flux at the NDL base challenges traditional concepts that the NDL was limited in terms of POC export. The dominant nutrient source for POC export fluxes should be subsurface nutrients, which was determined by 15N isotopic mass balance.
Clémence Paul, Clément Piel, Joana Sauze, Nicolas Pasquier, Frédéric Prié, Sébastien Devidal, Roxanne Jacob, Arnaud Dapoigny, Olivier Jossoud, Alexandru Milcu, and Amaëlle Landais
Biogeosciences, 20, 1047–1062, https://doi.org/10.5194/bg-20-1047-2023, https://doi.org/10.5194/bg-20-1047-2023, 2023
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To improve the interpretation of the δ18Oatm and Δ17O of O2 in air bubbles in ice cores, we need to better quantify the oxygen fractionation coefficients associated with biological processes. We performed a simplified analogue of the terrestrial biosphere in a closed chamber. We found a respiration fractionation in agreement with the previous estimates at the microorganism scale, and a terrestrial photosynthetic fractionation was found. This has an impact on the estimation of the Dole effect.
Adam Francis, Raja S. Ganeshram, Robyn E. Tuerena, Robert G. M. Spencer, Robert M. Holmes, Jennifer A. Rogers, and Claire Mahaffey
Biogeosciences, 20, 365–382, https://doi.org/10.5194/bg-20-365-2023, https://doi.org/10.5194/bg-20-365-2023, 2023
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Climate change is causing extensive permafrost degradation and nutrient releases into rivers with great ecological impacts on the Arctic Ocean. We focused on nitrogen (N) release from this degradation and associated cycling using N isotopes, an understudied area. Many N species are released at degradation sites with exchanges between species. N inputs from permafrost degradation and seasonal river N trends were identified using isotopes, helping to predict climate change impacts.
Mohamed Ayache, Jean-Claude Dutay, Kazuyo Tachikawa, Thomas Arsouze, and Catherine Jeandel
Biogeosciences, 20, 205–227, https://doi.org/10.5194/bg-20-205-2023, https://doi.org/10.5194/bg-20-205-2023, 2023
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The neodymium (Nd) is one of the most useful tracers to fingerprint water mass provenance. However, the use of Nd is hampered by the lack of adequate quantification of the external sources. Here, we present the first simulation of dissolved Nd concentration and Nd isotopic composition in the Mediterranean Sea using a high-resolution model. We aim to better understand how the various external sources affect the Nd cycle and particularly assess how it is impacted by atmospheric inputs.
Marta Santos-Garcia, Raja S. Ganeshram, Robyn E. Tuerena, Margot C. F. Debyser, Katrine Husum, Philipp Assmy, and Haakon Hop
Biogeosciences, 19, 5973–6002, https://doi.org/10.5194/bg-19-5973-2022, https://doi.org/10.5194/bg-19-5973-2022, 2022
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Terrestrial sources of nitrate are important contributors to the nutrient pool in the fjords of Kongsfjorden and Rijpfjorden in Svalbard during the summer, and they sustain most of the fjord primary productivity. Ongoing tidewater glacier retreat is postulated to favour light limitation and less dynamic circulation in fjords. This is suggested to encourage the export of nutrients to the middle and outer part of the fjord system, which may enhance primary production within and in offshore areas.
Marlene Dordoni, Michael Seewald, Karsten Rinke, Kurt Friese, Robert van Geldern, Jakob Schmidmeier, and Johannes A. C. Barth
Biogeosciences, 19, 5343–5355, https://doi.org/10.5194/bg-19-5343-2022, https://doi.org/10.5194/bg-19-5343-2022, 2022
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Organic matter (OM) turnover into dissolved inorganic carbon (DIC) was investigated by means of carbon isotope mass balances in Germany's largest water reservoir. This includes a metalimnetic oxygen minimum (MOM). Autochthonous particulate organic carbon (POC) was the main contributor to DIC, with rates that were highest for the MOM. Generally low turnover rates outline the environmental fragility of this water body in the case that OM loads increase due to storm events or land use changes.
Frédérique M. S. A. Kirkels, Hugo J. de Boer, Paulina Concha Hernández, Chris R. T. Martes, Marcel T. J. van der Meer, Sayak Basu, Muhammed O. Usman, and Francien Peterse
Biogeosciences, 19, 4107–4127, https://doi.org/10.5194/bg-19-4107-2022, https://doi.org/10.5194/bg-19-4107-2022, 2022
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The distinct carbon isotopic values of C3 and C4 plants are widely used to reconstruct past hydroclimate, where more C3 plants reflect wetter and C4 plants drier conditions. Here we examine the impact of regional hydroclimatic conditions on plant isotopic values in the Godavari River basin, India. We find that it is crucial to identify regional plant isotopic values and consider drought stress, which introduces a bias in C3 / C4 plant estimates and associated hydroclimate reconstructions.
Mhlangabezi Mdutyana, Tanya Marshall, Xin Sun, Jessica M. Burger, Sandy J. Thomalla, Bess B. Ward, and Sarah E. Fawcett
Biogeosciences, 19, 3425–3444, https://doi.org/10.5194/bg-19-3425-2022, https://doi.org/10.5194/bg-19-3425-2022, 2022
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Nitrite-oxidizing bacteria in the winter Southern Ocean show a high affinity for nitrite but require a minimum (i.e., "threshold") concentration before they increase their rates of nitrite oxidation significantly. The classic Michaelis–Menten model thus cannot be used to derive the kinetic parameters, so a modified equation was employed that also yields the threshold nitrite concentration. Dissolved iron availability may play an important role in limiting nitrite oxidation.
Weitian Ding, Urumu Tsunogai, Fumiko Nakagawa, Takashi Sambuichi, Hiroyuki Sase, Masayuki Morohashi, and Hiroki Yotsuyanagi
Biogeosciences, 19, 3247–3261, https://doi.org/10.5194/bg-19-3247-2022, https://doi.org/10.5194/bg-19-3247-2022, 2022
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Excessive leaching of nitrate from forested catchments during storm events degrades water quality and causes eutrophication in downstream areas. Thus, tracing the source of nitrate increase during storm events in forested streams is important for sustainable forest management. Based on the isotopic compositions of stream nitrate, including Δ17O, this study clarifies that the source of stream nitrate increase during storm events was soil nitrate in the riparian zone.
Nicolas Séon, Romain Amiot, Guillaume Suan, Christophe Lécuyer, François Fourel, Fabien Demaret, Arnauld Vinçon-Laugier, Sylvain Charbonnier, and Peggy Vincent
Biogeosciences, 19, 2671–2681, https://doi.org/10.5194/bg-19-2671-2022, https://doi.org/10.5194/bg-19-2671-2022, 2022
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We analysed the oxygen isotope composition of bones and teeth of four marine species possessing regional heterothermies. We observed a consistent link between oxygen isotope composition and temperature heterogeneities recorded by classical methods. This opens up new perspectives on the determination of the thermoregulatory strategies of extant marine vertebrates where conventional methods are difficult to apply, but also allows us to investigate thermophysiologies of extinct vertebrates.
Yuwei Liu, Guofeng Zhu, Zhuanxia Zhang, Zhigang Sun, Leilei Yong, Liyuan Sang, Lei Wang, and Kailiang Zhao
Biogeosciences, 19, 877–889, https://doi.org/10.5194/bg-19-877-2022, https://doi.org/10.5194/bg-19-877-2022, 2022
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We took the water cycle process of soil–plant–atmospheric precipitation as the research objective. In the water cycle of soil–plant–atmospheric precipitation, precipitation plays the main controlling role. The main source of replenishment for alpine meadow plants is precipitation and alpine meltwater; the main source of replenishment for forest plants is soil water; and the plants in the arid foothills mainly use groundwater.
Roberto Velázquez-Ochoa, María Julia Ochoa-Izaguirre, and Martín Federico Soto-Jiménez
Biogeosciences, 19, 1–27, https://doi.org/10.5194/bg-19-1-2022, https://doi.org/10.5194/bg-19-1-2022, 2022
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Our research is the first approximation to understand the δ13C macroalgal variability in one of the most diverse marine ecosystems in the world, the Gulf of California. The life-form is the principal cause of δ13C macroalgal variability, mainly taxonomy. However, changes in habitat characteristics and environmental conditions also influence the δ13C macroalgal variability. The δ13C macroalgae is indicative of carbon concentration mechanisms and isotope discrimination during carbon assimilation.
Raquel F. Flynn, Thomas G. Bornman, Jessica M. Burger, Shantelle Smith, Kurt A. M. Spence, and Sarah E. Fawcett
Biogeosciences, 18, 6031–6059, https://doi.org/10.5194/bg-18-6031-2021, https://doi.org/10.5194/bg-18-6031-2021, 2021
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Biological activity in the shallow Weddell Sea affects the biogeochemistry of recently formed deep waters. To investigate the drivers of carbon and nutrient export, we measured rates of primary production and nitrogen uptake, characterized the phytoplankton community, and estimated nutrient depletion ratios across the under-sampled western Weddell Sea in mid-summer. Carbon export was highest at the ice shelves and was determined by a combination of physical, chemical, and biological factors.
Stéphanie H. M. Jacquet, Christian Tamburini, Marc Garel, Aurélie Dufour, France Van Vambeke, Frédéric A. C. Le Moigne, Nagib Bhairy, and Sophie Guasco
Biogeosciences, 18, 5891–5902, https://doi.org/10.5194/bg-18-5891-2021, https://doi.org/10.5194/bg-18-5891-2021, 2021
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We compared carbon remineralization rates (MRs) in the western and central Mediterranean Sea in late spring during the PEACETIME cruise, as assessed using the barium tracer. We reported higher and deeper (up to 1000 m depth) MRs in the western basin, potentially sustained by an additional particle export event driven by deep convection. The central basin is the site of a mosaic of blooming and non-blooming water masses and showed lower MRs that were restricted to the upper mesopelagic layer.
Shinsuke Kawagucci, Yohei Matsui, Akiko Makabe, Tatsuhiro Fukuba, Yuji Onishi, Takuro Nunoura, and Taichi Yokokawa
Biogeosciences, 18, 5351–5362, https://doi.org/10.5194/bg-18-5351-2021, https://doi.org/10.5194/bg-18-5351-2021, 2021
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Hydrogen and carbon isotope ratios of methane as well as the relevant biogeochemical parameters and microbial community compositions in hydrothermal plumes in the Okinawa Trough were observed. We succeeded in simultaneously determining hydrogen and carbon isotope fractionation factors associated with aerobic oxidation of methane in seawater (εH = 49.4 ± 5.0 ‰, εC = 5.2 ± 0.4 ‰) – the former being the first of its kind ever reported.
Nicolai Schleinkofer, David Evans, Max Wisshak, Janina Vanessa Büscher, Jens Fiebig, André Freiwald, Sven Härter, Horst R. Marschall, Silke Voigt, and Jacek Raddatz
Biogeosciences, 18, 4733–4753, https://doi.org/10.5194/bg-18-4733-2021, https://doi.org/10.5194/bg-18-4733-2021, 2021
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We have measured the chemical composition of the carbonate shells of the parasitic foraminifera Hyrrokkin sarcophaga in order to test if it is influenced by the host organism (bivalve or coral). We find that both the chemical and isotopic composition is influenced by the host organism. For example strontium is enriched in foraminifera that grew on corals, whose skeleton is built from aragonite, which is naturally enriched in strontium compared to the bivalves' calcite shell.
Lena Rohe, Traute-Heidi Anderson, Heinz Flessa, Anette Goeske, Dominika Lewicka-Szczebak, Nicole Wrage-Mönnig, and Reinhard Well
Biogeosciences, 18, 4629–4650, https://doi.org/10.5194/bg-18-4629-2021, https://doi.org/10.5194/bg-18-4629-2021, 2021
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This is the first experimental setup combining a complex set of methods (microbial inhibitors and isotopic approaches) to differentiate between N2O produced by fungi or bacteria during denitrification in three soils. Quantifying the fungal fraction with inhibitors was not successful due to large amounts of uninhibited N2O production. All successful methods suggested a small or missing fungal contribution. Artefacts occurring with microbial inhibition to determine N2O fluxes are discussed.
Inga Köhler, Raul E. Martinez, David Piatka, Achim J. Herrmann, Arianna Gallo, Michelle M. Gehringer, and Johannes A. C. Barth
Biogeosciences, 18, 4535–4548, https://doi.org/10.5194/bg-18-4535-2021, https://doi.org/10.5194/bg-18-4535-2021, 2021
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We investigated how high Fe(II) levels influence the O2 budget of a circum-neutral Fe(II)-rich spring and if a combined study of dissolved O (DO) and its isotopic composition can help assess this effect. We showed that dissolved Fe(II) can exert strong effects on the δ18ODO even though a constant supply of atmospheric O2 occurs. In the presence of photosynthesis, direct effects of Fe oxidation become masked. Critical Fe(II) concentrations indirectly control the DO by enhancing photosynthesis.
Franziska Slotta, Lukas Wacker, Frank Riedel, Karl-Uwe Heußner, Kai Hartmann, and Gerhard Helle
Biogeosciences, 18, 3539–3564, https://doi.org/10.5194/bg-18-3539-2021, https://doi.org/10.5194/bg-18-3539-2021, 2021
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The African baobab is a challenging climate and environmental archive for its semi-arid habitat due to dating uncertainties and parenchyma-rich wood anatomy. Annually resolved F14C data of tree-ring cellulose (1941–2005) from a tree in Oman show the annual character of the baobab’s growth rings but were up to 8.8 % lower than expected for 1964–1967. Subseasonal δ13C and δ18O patterns reveal years with low average monsoon rain as well as heavy rainfall events from pre-monsoonal cyclones.
Peter M. J. Douglas, Emerald Stratigopoulos, Sanga Park, and Dawson Phan
Biogeosciences, 18, 3505–3527, https://doi.org/10.5194/bg-18-3505-2021, https://doi.org/10.5194/bg-18-3505-2021, 2021
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Hydrogen isotopes could be a useful tool to help resolve the geographic distribution of methane emissions from freshwater environments. We analyzed an expanded global dataset of freshwater methane hydrogen isotope ratios and found significant geographic variation linked to water isotopic composition. This geographic variability could be used to resolve changing methane fluxes from freshwater environments and provide more accurate estimates of the relative balance of global methane sources.
Veronica R. Rollinson, Julie Granger, Sydney C. Clark, Mackenzie L. Blanusa, Claudia P. Koerting, Jamie M. P. Vaudrey, Lija A. Treibergs, Holly C. Westbrook, Catherine M. Matassa, Meredith G. Hastings, and Craig R. Tobias
Biogeosciences, 18, 3421–3444, https://doi.org/10.5194/bg-18-3421-2021, https://doi.org/10.5194/bg-18-3421-2021, 2021
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We measured nutrients and the naturally occurring nitrogen (N) and oxygen (O) stable isotope ratios of nitrate discharged from a New England river over an annual cycle, to monitor N loading and identify dominant sources from the watershed. We uncovered a seasonality to loading and sources of N from the watershed. Seasonality in the nitrate isotope ratios also informed on N cycling, conforming to theoretical expectations of riverine nutrient cycling.
Zixun Chen, Xuejun Liu, Xiaoqing Cui, Yaowen Han, Guoan Wang, and Jiazhu Li
Biogeosciences, 18, 2859–2870, https://doi.org/10.5194/bg-18-2859-2021, https://doi.org/10.5194/bg-18-2859-2021, 2021
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δ13C in plants is a sensitive long-term indicator of physiological acclimatization. The present study suggests that precipitation change and increasing atmospheric N deposition have little impact on δ13C of H. ammodendron, a dominant plant in central Asian deserts, but affect its gas exchange. In addition, this study shows that δ13C of H. ammodendron could not indicate its water use efficiency (WUE), suggesting that whether δ13C of C4 plants indicates WUE is species-specific.
Petra Zahajská, Carolina Olid, Johanna Stadmark, Sherilyn C. Fritz, Sophie Opfergelt, and Daniel J. Conley
Biogeosciences, 18, 2325–2345, https://doi.org/10.5194/bg-18-2325-2021, https://doi.org/10.5194/bg-18-2325-2021, 2021
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The drivers of high accumulation of single-cell siliceous algae (diatoms) in a high-latitude lake have not been fully characterized before. We studied silicon cycling of the lake through water, radon, silicon, and stable silicon isotope balances. Results showed that groundwater brings 3 times more water and dissolved silica than the stream inlet. We demonstrate that groundwater discharge and low sediment deposition have driven the high diatom accumulation in the studied lake in the past century.
Yu-Te Hsieh, Walter Geibert, E. Malcolm S. Woodward, Neil J. Wyatt, Maeve C. Lohan, Eric P. Achterberg, and Gideon M. Henderson
Biogeosciences, 18, 1645–1671, https://doi.org/10.5194/bg-18-1645-2021, https://doi.org/10.5194/bg-18-1645-2021, 2021
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The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions in the oceans, but the sources and fluxes of trace elements (TEs) to this region remain unclear. This study investigates seawater Ra-228 and provides important constraints on ocean mixing and dissolved TE fluxes to this region. Vertical mixing is a more important source than aeolian or shelf inputs in this region, but particulate or winter deep-mixing inputs may be required to balance the TE budgets.
Zhongjie Yu and Emily M. Elliott
Biogeosciences, 18, 805–829, https://doi.org/10.5194/bg-18-805-2021, https://doi.org/10.5194/bg-18-805-2021, 2021
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In this study, we demonstrated distinct nitrogen isotope effects for nitric oxide (NO) production from major microbial and chemical NO sources in an agricultural soil. These results highlight characteristic bond-forming and breaking mechanisms associated with microbial and chemical NO production and implicate that simultaneous isotopic analyses of NO and nitrous oxide (N2O) can lead to unprecedented insights into the sources and processes controlling NO and N2O emissions from agricultural soils.
Daniel A. Frick, Rainer Remus, Michael Sommer, Jürgen Augustin, Danuta Kaczorek, and Friedhelm von Blanckenburg
Biogeosciences, 17, 6475–6490, https://doi.org/10.5194/bg-17-6475-2020, https://doi.org/10.5194/bg-17-6475-2020, 2020
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Silicon is taken up by some plants to increase structural stability and to develop stress resistance and is rejected by others. To explore the underlying mechanisms, we used the stable isotopes of silicon that shift in their relative abundance depending on the biochemical transformation involved. On species with a rejective (tomato, mustard) and active (wheat) uptake mechanism, grown in hydroculture, we found that the transport of silicic acid is controlled by the precipitation of biogenic opal.
Quentin Charbonnier, Julien Bouchez, Jérôme Gaillardet, and Éric Gayer
Biogeosciences, 17, 5989–6015, https://doi.org/10.5194/bg-17-5989-2020, https://doi.org/10.5194/bg-17-5989-2020, 2020
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The abundance and isotope composition of the trace metal barium (Ba) allows us to track and quantify nutrient cycling throughout the Amazon Basin. In particular, we show that the Ba biological fingerprint evolves from that of a strong net nutrient uptake in the mountainous area of the Andes towards efficient nutrient recycling on the plains of the Lower Amazon. Our study highlights the fact that the geochemical signature of rock-derived nutrients transported by the Amazon is scarred by life.
Ajinkya G. Deshpande, Thomas W. Boutton, Ayumi Hyodo, Charles W. Lafon, and Georgianne W. Moore
Biogeosciences, 17, 5639–5653, https://doi.org/10.5194/bg-17-5639-2020, https://doi.org/10.5194/bg-17-5639-2020, 2020
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Wetland forests in the southern USA are threatened by changing climate and human-induced pressures. We used tree ring widths and C isotopes as indicators of forest growth and physiological stress, respectively, and compared these to past climate data. We observed that vegetation growing in the drier patches is susceptible to stress, while vegetation growth and physiology in wetter patches is less sensitive to unfavorable environmental conditions, highlighting the importance of optimal wetness.
Dominika Lewicka-Szczebak, Maciej Piotr Lewicki, and Reinhard Well
Biogeosciences, 17, 5513–5537, https://doi.org/10.5194/bg-17-5513-2020, https://doi.org/10.5194/bg-17-5513-2020, 2020
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We present the first validation of N2O isotopic approaches for estimating N2O source pathways and N2O reduction. These approaches are widely used for tracing soil nitrogen cycling, but the results of these estimations are very uncertain. Here we report the results from parallel treatments allowing for precise validation of these approaches, and we propose the best strategies for results interpretation, including the new idea of an isotope model integrating three isotopic signatures of N2O.
Markus Raitzsch, Claire Rollion-Bard, Ingo Horn, Grit Steinhoefel, Albert Benthien, Klaus-Uwe Richter, Matthieu Buisson, Pascale Louvat, and Jelle Bijma
Biogeosciences, 17, 5365–5375, https://doi.org/10.5194/bg-17-5365-2020, https://doi.org/10.5194/bg-17-5365-2020, 2020
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The isotopic composition of boron in carbonate shells of marine unicellular organisms is a popular tool to estimate seawater pH. Usually, many shells need to be dissolved and measured for boron isotopes, but the information on their spatial distribution is lost. Here, we investigate two techniques that allow for measuring boron isotopes within single shells and show that they yield robust mean values but provide additional information on the heterogeneity within and between single shells.
Florian Einsiedl, Anja Wunderlich, Mathieu Sebilo, Ömer K. Coskun, William D. Orsi, and Bernhard Mayer
Biogeosciences, 17, 5149–5161, https://doi.org/10.5194/bg-17-5149-2020, https://doi.org/10.5194/bg-17-5149-2020, 2020
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Nitrate pollution of freshwaters and methane emissions into the atmosphere are crucial factors in deteriorating the quality of drinking water and in contributing to global climate change. Here, we report vertical concentration and stable isotope profiles of CH4, NO3-, NO2-, and NH4+ in the water column of Fohnsee (southern Bavaria, Germany) that may indicate linkages between nitrate-dependent anaerobic methane oxidation and the anaerobic oxidation of ammonium.
Ruifang C. Xie, Frédéric A. C. Le Moigne, Insa Rapp, Jan Lüdke, Beat Gasser, Marcus Dengler, Volker Liebetrau, and Eric P. Achterberg
Biogeosciences, 17, 4919–4936, https://doi.org/10.5194/bg-17-4919-2020, https://doi.org/10.5194/bg-17-4919-2020, 2020
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Thorium-234 (234Th) is widely used to study carbon fluxes from the surface ocean to depth. But few studies stress the relevance of oceanic advection and diffusion on the downward 234Th fluxes in nearshore environments. Our study in offshore Peru showed strong temporal variations in both the importance of physical processes on 234Th flux estimates and the oceanic residence time of 234Th, whereas salinity-derived seawater 238U activities accounted for up to 40 % errors in 234Th flux estimates.
Ralf A. Oeser and Friedhelm von Blanckenburg
Biogeosciences, 17, 4883–4917, https://doi.org/10.5194/bg-17-4883-2020, https://doi.org/10.5194/bg-17-4883-2020, 2020
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We present a novel strategy to decipher the relative impact of biogenic and abiotic drivers of weathering. We parameterized the nutrient fluxes in four ecosystems along a climate and vegetation gradient situated on the Chilean Coastal Cordillera. We investigated how nutrient demand by plants drives weathering. We found that the increase in biomass nutrient demand is accommodated by faster nutrient recycling rather than an increase in the weathering–release rates.
Tito Arosio, Malin M. Ziehmer, Kurt Nicolussi, Christian Schlüchter, and Markus Leuenberger
Biogeosciences, 17, 4871–4882, https://doi.org/10.5194/bg-17-4871-2020, https://doi.org/10.5194/bg-17-4871-2020, 2020
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Stable isotopes in tree-ring cellulose are tools for climatic reconstructions, but interpretation is challenging due to nonclimate trends. We analyzed the tree-age trends in tree-ring isotopes of deciduous larch and evergreen cembran pine. Samples covering the whole Holocene were collected at the tree line in the Alps. For cambial ages over 100 years, we prove the absence of age trends in δD, δ18O, and δ13C for both species. For lower cambial ages, trends differ for each isotope and species.
Yuyang He, Xiaobin Cao, and Huiming Bao
Biogeosciences, 17, 4785–4795, https://doi.org/10.5194/bg-17-4785-2020, https://doi.org/10.5194/bg-17-4785-2020, 2020
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Different carbon sites in a large organic molecule have different isotope compositions. Different carbon sites may not have the chance to exchange isotopes at all. The lack of appreciation of this notion might be blamed for an unsettled debate on the thermodynamic state of an organism. Here we demonstrate using minerals, N2O, and acetic acid that the dearth of exchange among different carbon sites renders them as independent as if they were different elements in organic molecules.
Felix M. Spielmann, Albin Hammerle, Florian Kitz, Katharina Gerdel, and Georg Wohlfahrt
Biogeosciences, 17, 4281–4295, https://doi.org/10.5194/bg-17-4281-2020, https://doi.org/10.5194/bg-17-4281-2020, 2020
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Carbonyl sulfide (COS) can be used as a proxy for plant photosynthesis on an ecosystem scale. However, the relationships between COS and CO2 fluxes and their dependence on daily to seasonal changes in environmental drivers are still poorly understood. We examined COS and CO2 ecosystem fluxes above an agriculturally used mountain grassland for 6 months. Harvesting of the grassland disturbed the otherwise stable COS-to-CO2 uptake ratio. We even found the canopy to release COS during those times.
Getachew Agmuas Adnew, Thijs L. Pons, Gerbrand Koren, Wouter Peters, and Thomas Röckmann
Biogeosciences, 17, 3903–3922, https://doi.org/10.5194/bg-17-3903-2020, https://doi.org/10.5194/bg-17-3903-2020, 2020
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We measured the effect of photosynthesis, the largest flux in the carbon cycle, on the triple oxygen isotope composition of atmospheric CO2 at the leaf level during gas exchange using three plant species. The main factors that limit the impact of land vegetation on the triple oxygen isotope composition of atmospheric CO2 are identified, characterized and discussed. The effect of photosynthesis on the isotopic composition of CO2 is commonly quantified as discrimination (ΔA).
Moritz Schroll, Frank Keppler, Markus Greule, Christian Eckhardt, Holger Zorn, and Katharina Lenhart
Biogeosciences, 17, 3891–3901, https://doi.org/10.5194/bg-17-3891-2020, https://doi.org/10.5194/bg-17-3891-2020, 2020
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Short summary
Fungi have recently been identified to produce the greenhouse gas methane. Here, we investigated the stable carbon isotope values of methane produced by saprotrophic fungi. Our results show that stable isotope values of methane from fungi are dependent on the fungal species and the metabolized substrate. They cover a broad range and overlap with stable carbon isotope values of methane reported for methanogenic archaea, the thermogenic degradation of organic matter, and other eukaryotes.
Cited articles
Aksenov, Y., Bacon, S., Coward, A. C., and Holliday, P.: Polar outflow from
the Arctic Ocean: A high resolution model study, J. Mar. Syst. 83, 14–37,
https://doi.org/10.1016/j.jmarsys.2010.06.007, 2010.
Altabet, M. A., Pilskaln, C., Thunell, R., Pride, C., Sigman, D. M., Chavez,
F., and Francois, R.: The nitrogen isotope biogeochemistry of sinking
particles from the margin of the eastern North Pacific, Deep.-Sea Res. Pt. I,
46, 655–679, https://doi.org/10.1016/S0967-0637(98)00084-3, 1999.
Anderson, L. A. and Sarmiento, J. L.: Redfield ratios of remineralization
determined by nutrient data analysis, Global Biogeochem. Cy., 8, 65–80,
https://doi.org/10.1029/93GB03318, 1994.
Arrigo, K. and van Dijken, G. L.: Secular trends in Arctic Ocean net
primary production, J. Geophys. Res., 116, C09011, https://doi.org/10.1029/2011JC007151, 2011.
Azetsu-Scott, K., Petrie, B., Yeats, P., and Lee, C.: Composition and fluxes
of freshwater through Davis Strait using multiple chemical tracers, J.
Geophys. Res., 117, C12011, https://doi.org/10.1029/2012JC008172, 2012.
Benetti, M., Reverdin, G., Lique, C., Yashayaev, I., Holliday, N. P., Tynan,
E., Torres-Valdes, S., Lherminier, P., Treguer, P., and Sarthou, G.:
Composition of freshwater in the spring of 2014 on the southern Labrador
shelf and slope, J. Geophys. Res.-Ocean., 122, 1102–1121, https://doi.org/10.1002/2016JC012244, 2017.
Blais, M., Tremblay, J.-É., Jungblut, A. D., Gagnon, J., Martin, J.,
Thaler, M., and Lovejoy, C.: Nitrogen fixation and identification of
potential diazotrophs in the Canadian Arctic, Global Biogeochem. Cy., 26, GB3022,
https://doi.org/10.1029/2011GB004096, 2012.
Böhlke, J. K., Mroczkowski, S. J., and Coplen, T. B.: Oxygen isotopes in
nitrate: new reference materials for 18O : 17O : 16O measurements
and observations on nitrate-water equilibration, Rapid Commun. Mass
Sp., 17, 1835–1846, https://doi.org/10.1002/rcm.1123, 2003.
Bourke, R. H., Addison, V. G., and Paquette, R. G.: Oceanography of Nares
Strait and northern Baffin Bay in 1986 with emphasis on deep and bottom
water formation, J. Geophys. Res., 94, 8289–8302, https://doi.org/10.1029/JC094iC06p08289, 1989.
Brandes, J. A. and Devol, A. H.: Isotopic fractionation of oxygen and
nitrogen in coastal marine sediments, Geochim. Cosmochim. Ac., 61,
1793–1801, https://doi.org/10.1016/S0016-7037(97)00041-0, 1997.
Brown, Z. W., Casciotti, K. L., Pickart, R. S., Swift, J. H., and Arrigo, K.
R.: Aspects of the marine nitrogen cycle of the Chukchi Sea shelf and Canada
Basin, Deep-Sea Res. Pt. II, 118, 73–87, https://doi.org/10.1016/j.dsr2.2015.02.009,
2015.
Buchwald, C., Santoro, A. E., McIlvin, M. R., and Casciotti, K. L.: Oxygen
isotopic composition of nitrate and nitrite produced by nitrifying
cocultures and natural marine assemblages, Limnol. Oceanogr., 57,
1361–1375, https://doi.org/10.4319/lo.2012.57.5.1361, 2012.
Carmack, E. C. and McLaughlin, F. A.: Towards recognition of physical and
geochemical change in Subarctic and Arctic Seas, Prog. Oceanogr., 90,
90–104, https://doi.org/10.1016/j.pocean.2011.02.007, 2011.
Carmack, E. C., Yamamoto-Kawai, M., Haine, T. W. N., Bacon, S., Bluhm, B.
A., Lique, C., Melling, H., Polyakov, I. V., Straneo, F., Timmermans, M. L.,
and Williams, W. J.: Freshwater and its role in the Arctic Marine System:
Sources, disposition, storage, export, and physical and biogeochemical
consequences in the Arctic and global oceans, J. Geophys. Res.-Biogeo.,
121, 675–717, https://doi.org/10.1002/2015JG003140, 2016.
Casciotti, K. L., Sigman, D. M., Hastings, M. G., Böhlke, J. K., and
Hilkert, A.: Measurement of the oxygen isotopic composition of nitrate in
seawater and freshwater using the denitrifier method, Anal. Chem., 74,
4905–4912, https://doi.org/10.1021/ac020113w, 2002.
Casciotti, K. L., Trull, T. W., Glover, D. M., and Davies, D.: Constraints on
nitrogen cycling at the subtropical North Pacific Station ALOHA from
isotopic measurements of nitrate and particulate nitrogen, Deep-Sea Res. Pt. II,
55, 1661–1672, https://doi.org/10.1016/j.dsr2.2008.04.017, 2008.
Chang, B. X. and Devol, A. H.: Seasonal and spatial patterns of sedimentary
denitrification rates in the Chukchi sea, Deep-Sea Res. Pt. II, 56,
1339–1350, https://doi.org/10.1016/j.dsr2.2008.10.024,
2009.
Colbourne, E., Holden, J., Senciall, D., Bailey, W., Snook, S., and Higdon, J.: Physical Oceanographic Conditions on the Newfoundland and Labrador Shelf during 2015, DFO Can. Sci. Advis. Sec. Res. Doc., 2016/079, v +40 p., 2016.
Cormier. M.-A., Rochon, A., de Vernal, A., and Gélinas, Y.: Multi-proxy
study of primary production and paleoceanographical conditions in northern
Baffin Bay during the last centuries, Mar. Micropaleontol., 127, 1–10,
https://doi.org/10.1016/j.marmicro.2016.07.001, 2020.
Cuny, J., Rhines, P. B., Niiler, P. P., and Bacon, S.: Labrador Sea Boundary
Currents and the Fate of the Irminger Sea Water, J. Phys. Oceanogr., 32,
627–647, https://doi.org/10.1175/1520-0485(2002)032{%}3C0627:LSBCAT{%}3E2.0.CO;2, 2002.
de la Vega, C., Mahaffey, C., Tuerena, R. E., Yurkowski, D. J., Ferguson, S.
H., Stenson, G. B., Nordøy, E. S., Haug, T., Biuw, M., Smout, S.,
Hopkins, J., Tagliabue, A., and Jeffreys, R. M.: Arctic seals as tracers of
environmental and ecological change, Limnol. Oceanogr. Lett., 6, 24–32,
https://doi.org/10.5285/66AAF3C8-FA58-41DE-8EF1-480A2E125408, 2021.
Deutsch, C., Gruber, N., Key, R. M., Sarmiento, J. L., and Ganachaud, A.:
Denitrification and N2 fixation in the Pacific Ocean, Global
Biogeochem. Cy., 15, 483–506, https://doi.org/10.1029/2000GB001291, 2001.
Devol, A. H., Codispoti, L. A., and Christensen, J. P.: Summer and winter
denitrification rates in western Arctic shelf sediments, Cont. Shelf Res.,
17, 1029–1050, https://doi.org/10.1016/S0278-4343(97)00003-4, 1997.
Drinkwater, K. F., Belgrano, A., Borja, A., Conversi, A., Edwards, M.,
Greene, C. H., Otterson, G., Pershing, A. J., and Walker, H.: The Response
of Marine Ecosystems to Climate Variability Associated With the North
Atlantic Oscillation, Geophys. Monog.-Am. Geophys. Union, 134, 211–234,
https://doi.org/10.1029/134GM10, 2003.
Ferland, J., Gosselin, M., and Starr, M.: Environmental control of summer
primary production in the Hudson Bay system: The role of stratification, J.
Mar. Syst., 88, 385–400, https://doi.org/10.1016/j.jmarsys.2011.03.015, 2011.
Fragoso, G. M., Poulton, A. J., Yashayaev, I. M., Head, E. J. H., and
Purdie, D. A.: Spring phytoplankton communities of the Labrador Sea
(2005–2014): pigment signatures, photophysiology and elemental ratios,
Biogeosciences, 14, 1235–1259, https://doi.org/10.5194/bg-14-1235-2017, 2017.
Frajka-Williams, E. and Rhines, P. B.: Physical controls and interannual
variability of the Labrador Sea spring phytoplankton bloom in distinct
regions, Deep-Sea Res. Pt. I, 57, 541–552, https://doi.org/10.1016/j.dsr.2010.01.003, 2010.
Fratantoni, P. S. and Pickart, R. S.: The Western North Atlantic Shelfbreak
Current System in Summer, J. Phys. Oceanogr., 37, 2509–2533, https://doi.org/10.1175/JPO3123.1, 2007.
Fripiat, F., Declercq, M., Sapart, C. J., Anderson, L. G., Bruechert, V.,
Deman, F., Fonseca-Batista, D., Humborg, C., Roukaerts, A., Semiletov, I. P.,
and Dehairs, F.: Influence of the bordering shelves on nutrient distribution
in the Arctic halocline inferred from water column nitrate isotopes, Limnol.
Oceanogr., 63, 2154–2170, https://doi.org/10.1002/lno.10930, 2018.
Galbraith, E. D. and Kienast, M.: The acceleration of oceanic
denitrification during deglacial warming, Nat. Geosci., 6, 579–584,
https://doi.org/10.1038/ngeo1832, 2013.
Gonfiantini, R.: Stable Isotope Reference Samples for Geochemical and
Hydrological Investigations, Int. J. Appl. Radiat. Is., 35, 426,
https://doi.org/10.1016/0020-708X(84)90059-0, 1984.
Granger, J. and Wankel, S. D.: Isotopic overprinting of nitrification on
denitrification as a ubiquitous and unifying feature of environmental
nitrogen cycling, P. Natl. Acad. Sci. USA, 113, E6391–E6400. https://doi.org/10.1073/pnas.1601383113, 2016
Granger, J., Sigman, D. M., Needoba, J. A., and Harrison, P. J.: Coupled
nitrogen and oxygen isotope fractionation of nitrate during assimilation by
cultures of marine phytoplankton, Limnol. Oceanogr., 49, 1763–1773,
https://doi.org/10.4319/lo.2004.49.5.1763, 2004.
Granger, J., Sigman, D. M., Lehmann, M. F., and Tortell, P. D.: Nitrogen and
oxygen isotope fractionation during dissimilatory nitrate reduction by
denitrifying bacteria, Limnol. Oceanogr., 53, 2533–2545, https://doi.org/10.4319/lo.2008.53.6.2533, 2008.
Granger, J., Prokopenko, M. G., Sigman, D. M., Mordy, C. W., Morse, Z. M.,
Morales, L. V., Sambrotto, R. N., and Plessen, B.: Coupled
nitrification-denitrification in sediment of the eastern Bering Sea shelf
leads to 15N enrichment of fixed N in shelf waters, J. Geophys. Res.-Ocean.,
116, C11006, https://doi.org/10.1029/2010JC006751, 2011.
Granger, J., Sigman, D. M., Gagnon, J., Tremblay, J.-E., and Mucci, A.: On
the Properties of the Arctic Halocline and Deep Water Masses of the Canada
Basin from Nitrate Isotope Ratios, J. Geophys. Res.-Ocean., 123,
5443–5458, https://doi.org/10.1029/2018JC014110, 2018.
Grasshoff, K.: A simultaneous multiple channel system for nutrient analysis
in seawater with analog and digital analog record, Adv. Autom. Anal. Tech.
Int. Conf., 11, 133–145, 1969.
Greene, C. H., Meyer-Gutbrod, E., Monger, B. C., McGarry, L. P., Pershing,
A. J., Belkin, I. M., Fratantoni, P. S., Mountain, D. G., Pickart, R. S.,
Proshutinsky, A., Ji, R., Bisagni, J. J., Hakkinen, S. M. A., Haidvogel, D.
B., Wang, J., Head, E., Smith, P., Reid, P. C., and Conversi, A.: Remote
climate forcing of decadal-scale regime shifts in Northwest Atlantic shelf
ecosystems, Limnol. Oceanogr., 58, 803–816, https://doi.org/10.4319/lo.2013.58.3.0803, 2013.
Gruber, N. and Sarmiento, J. L.: Global patterns of marine nitrogen fixation
and denitrification, Global Biogeochem. Cy., 11, 235–266, https://doi.org/10.1029/97GB00077, 1997.
Hansen, J., H., Hedeholm, R. B., Sünksen, K.,
Christensen, J. T., and Grønkjær, P: Spatial variability of carbon
(δ13C) and nitrogen (δ15N) stable isotope ratios
in an Arctic marine food web, Mar. Ecol. Prog. Ser., 467, 47–57, https://doi.org/10.3354/meps09945, 2012.
Hansen, M. O., Nielsen, T. G., Stedmon, C. A., and Munkm, P.: Oceanographic
regime shift during 1997 in Disko Bay, Western Greenland, Limnol. Oceanogr.,
57, 634–644, https://doi.org/10.4319/lo.2012.57.2.0634, 2012.
Harding, K., Turk-Kubo, K. A., Sipler, R. E., Mills, M. M., Bronk, D. A., and
Zehr, J. P.: Symbiotic unicellular cyanobacteria fix nitrogen in the Arctic
Ocean, P. Natl. Acad. Sci. USA, 115, 13371–13375, https://doi.org/10.1073/pnas.1813658115, 2018.
Harrison, W. G. and Li, W. K. W.: Phytoplankton Growth and Regulation in
the Labrador Sea: Light and Nutrient Limitation, J. Northw. Atl. Fish. Sci.,
39, 71–82, https://doi.org/10.2960/J.v39.m592, 2008.
Harrison, W. G., Platt, T., and Irwin, B.: Primary Production and Nutrient
Assimilation by Natural Phytoplankton Populations of the Eastern Canadian
Arctic, Can. J. Fish. Aquat. Sci., 39, 335–345, https://doi.org/10.1139/f82-046, 1982.
Harrison, W. G., Børsheim, K. Y., Li, W. K., Maillet, G. L., Pepin, P.,
Sakshaug, E., Skogen, M. D., and Yeats, P. A.: Phytoplankton production and
growth regulation in the Subarctic North Atlantic: A comparative study of
the Labrador Sea-Labrador/Newfoundland shelves and
Barents/Norwegian/Greenland seas and shelves, Prog. Oceanogr., 114, 26–45,
https://doi.org/10.1016/j.pocean.2013.05.003, 2013.
Hedeholm, R., Grønkjær, P., and Rysgaard, S.: Feeding ecology of
capelin (Mallotus villosus Muller) in West Greenland waters, Polar Biol., 35, 1533–1543,
https://doi.org/10.1007/s00300-012-1193-4, 2012.
Jakobsen, P. K., Ribergaard, M. H., Quadfasel, D., Schmith, T., and Hughes,
C. W.: Near-surface circulation in the northern North Atlantic as inferred
from Lagrangian drifters: Variability from the mesoscale to interannual, J.
Geophys. Res., 108, 3251, https://doi.org/10.1029/2002JC001554, 2003.
Jenkins, W. J., Smethie, W. M., Boyle, E. A., and Cutter, G. A.: Water mass
analysis for the U.S. GEOTRACES (GA03) North Atlantic sections, Deep-Sea
Res. Pt. II, 116, 6–20, https://doi.org/10.1016/j.dsr2.2014.11.018, 2015.
Jones, E. P.: Tracing Pacific water in the North Atlantic Ocean, J. Geophys.
Res., 108, 3116, https://doi.org/10.1029/2001JC001141, 2003.
Jones, E. P., Anderson, L. G., and Swift, J. H.: Distribution of Atlantic and
Pacific waters in the upper Arctic Ocean: Implications for circulation,
Geophys. Res. Lett., 25, 765–768, https://doi.org/10.1029/98GL00464, 1998.
Kelley, D. and Richards, C.: oce: Analysis of Oceanographic Data, R package
version 0.9-22, available at: https://cran.r-project.org/web/packages/oce/oce.pdf
(last access: 20 July 2021), 2017.
Kienast, M., Davin, S., Doering, K., Hebbeln, D., Kienast, S., Lehmann, N.,
Schneider, R., Sherwood, O., and Weiser, J.: Isotopic evidence for changes
in the origin and cycling of nitrogen in the Labrador Sea during the last
8,000 years, EGU General Assembly Online, 4–8 May 2020, EGU2020–12134,
https://doi.org/10.5194/egusphere-egu2020-12134, 2020.
Klein, B., LeBlanc, B., Mei, Z.-P., Beret, R., Michaud, J., Mundy, C.-J.,
von Quillfeldt, C. H., Garneau, M.-È., Roy, S., and Gratton, Y.:
Phytoplankton biomass, production and potential export in the North Water,
Deep-Sea Res. Pt. II, 49, 4983–5002, https://doi.org/10.1016/S0967-0645(02)00174-1, 2002.
Lalande, C., Forest, A., Barber, D. G., Gratton, Y., and Fortier, L.:
Variability in the annual cycle of vertical particulate organic carbon
export on Arctic shelves: Contrasting the Laptev Sea, Northern Baffin Bay
and the Beaufort Sea, Cont. Shelf Res., 29, 2157–2165, https://doi.org/10.1016/j.csr.2009.08.009, 2009.
Lehmann, M. F., Bernasconi, S. F., Barbieri, A., and McKenzie, J. A.:
Preservation of organic matter and alteration of its carbon and nitrogen
isotope composition during simulated and in situ early sedimentary
diagenesis, Geochim. Cosmochim. Ac., 66, 3573–3584, https://doi.org/10.1016/S0016-7037(02)00968-7, 2002.
Lehmann, M. F., Sigman, D. M., McCorkle, D. C., Brunelle, B. G., Hoffmann,
S., Kienast, M., Cane, G., and Clement, J.: Origin of the deep Bering Sea
nitrate deficit: Constraints from the nitrogen and oxygen isotopic
composition of water column nitrate and benthic nitrate fluxes, Global
Biogeochem. Cy., 19, GB4005, https://doi.org/10.1029/2005GB002508, 2005.
Lehmann, M. F., Sigman, D. M., McCorkle, D. C., Granger, J., Hoffmann, S.,
Cane, G., and Brunelle, B. B.: The distribution of nitrate 15N : 14N
in marine sediments and the impact of benthic nitrogen loss on the isotopic
composition of oceanic nitrate, Geochim. Cosmochim. Ac., 71, 5384–5404,
https://doi.org/10.1016/j.gca.2007.07.025, 2007.
Lehmann, N., Granger, J., Kienast, M., Brown, K. S., Rafter, P. A., Martinez Mendes, G. M., and Mohtadi, M.: Isotopic Evidence for the Evolution of Subsurface Nitrate in the Western Equatorial Pacific, Geophys. Res. Ocean., 123, https://doi.org/10.1002/2017JC013527, 2018.
Lehmann, N., Kienast, M., Granger, J., Bourbonnais, A., Altabet, M. A., and
Tremblay, J.-É.: Remote western Arctic nutrients fuel remineralization
in deep Baffin Bay, Global Biogeochem. Cy., 33, 649–667, https://doi.org/10.1029/2018GB006134, 2019.
Limoges, A., Weckström, K., Ribeiro, S., Georgiadis, E., Hansen, K. E.,
Martinez, P., Seidenkrantz, M.-S., Giraudeau, J., Crosta, X., and Massé, G.: Learning from the past: Impact of the Arctic Oscillation on sea ice and
marine productivity off northwest Greenland over the last 9,000 years, Glob.
Change Biol., 26, 6767–6786, https://doi.org/10.1111/gcb.15334, 2020.
Macdonald, R. W., Anderson, L. G., Christensen, J. P., Miller, L. A., Semiletov, I. P., and Stein, R.: Polar margins: the Arctic Ocean. Carbon and nutrient fluxes in continental margins: a global synthesis, 291–303,
https://doi.org/10.1007/978-3-540-92735-8_6, 2010.
Marconi, D., Weigand, M. A., Rafter, P. A., McIlvin, M. R., Forbes, M.,
Casciotti, K. L., and Sigman, D. M.: Nitrate isotope distributions on the US
GEOTRACES North Atlantic cross-basin section: Signals of polar nitrate
sources and low latitude nitrogen cycling, Mar. Chem., 177, 143–156,
https://doi.org/10.1016/j.marchem.2015.06.007, 2015.
Martin, J., Tremblay, J.-É., Gagnon, J., Tremblay, G., Lapoussière,
A., Jose, C., Poulin, M., Gosselin, M., Gratton, Y., and Michel, C.:
Prevalence, structure and properties of subsurface chlorophyll maxima in
Canadian Arctic waters, Mar. Ecol. Prog. Ser., 412, 69–84, https://doi.org/10.3354/meps08666, 2010.
McIlvin, M. R. and Casciotti, K. L.: Fully automated system for stable
isotopic analyses of dissolved nitrous oxide at natural abundance levels,
Limnol. Oceanogr. Method., 8, 54–66, https://doi.org/10.4319/lom.2010.8.54, 2010.
McIlvin, M. R. and Casciotti, K. L.: Technical Updates to the Bacterial
Method for Nitrate Isotopic Analyses, Anal. Chem., 83, 1850–1856,
https://doi.org/10.1021/ac1028984, 2011.
McLaughlin, F. A., Carmack, E. C., Macdonald, R. W., and Bishop, J. K. B.:
Physical and geochemical properties across the Atlantic/Pacific water mass
front in the southern Canadian Basin, J. Geophys. Res.-Ocean., 101,
1183–1197, https://doi.org/10.1029/95JC02634, 1996.
McLaughlin, F. A., Carmack, E. C., Macdonald, R. W., Melling, H., Swift, J.
H., Wheeler, P. A., Sherr, B. F., and Sherr, E. B.: The joint roles of
Pacific and Atlantic-origin waters in the Canada Basin, 1997–1998, Deep-Sea
Res. Pt. I, 51, 107–128, https://doi.org/10.1016/j.dsr.2003.09.010, 2004.
Michel, C., Gosselin, M., and Nozais, C.: Preferential sinking export of
biogenic silica during the spring and summer in the North Water Polynya
(northern Baffin Bay): Temperature or biological control?, J. Geophys. Res.,
107, 3064, https://doi.org/10.1029/2000JC000408, 2002.
Mills, M. M., Brown, Z. W., Lowry, K. E., van Dijken, G. L., Becker, S.,
Pal,S., Benitez-Nelson, C. R., Downer, M. M., Strong, A. L., Swift, J. H.,
Pickart, R. S., and Arrigo, K. R.: Impacts of low phytoplankton
NO
Minagawa, M. and Wada, E.: Stepwise enrichment of 15N along food
chains: Further evidence and the relation between δ15N and
animal age, Geochim. Cosmochim. Ac., 48, 1135–1140, https://doi.org/10.1016/0016-7037(84)90204-7, 1984.
Münchow, A., Falkner, K. K., and Melling, H.: Baffin island and west
Greenland current systems in northern Baffin bay, Prog. Oceanogr., 132,
305–317, https://doi.org/10.1016/j.pocean.2014.04.001, 2015.
Muzuka, A. N. and Hillaire-Marcel, C.: Burial rates of organic matter along
the eastern Canadian margin and stable isotope constraints on its origin and
diagenetic evolution, Mar. Geol., 160, 251–270, https://doi.org/10.1016/S0025-3227(99)00022-5, 1999.
Needoba, J. A., Waser, N. A., Harrison, P. J., and Calvert, S. E.: Nitrogen
isotope fractionation in 12 species of marine phytoplankton during growth on
nitrate, Mar. Ecol. Prog. Ser., 255, 81–91 https://doi.org/10.3354/meps255081, 2003.
Olsen, A., Lange, N., Key, R. M., Tanhua, T., Álvarez, M., Becker, S., Bittig, H. C., Carter, B. R., Cotrim da Cunha, L., Feely, R. A., van Heuven, S., Hoppema, M., Ishii, M., Jeansson, E., Jones, S. D., Jutterström, S., Karlsen, M. K., Kozyr, A., Lauvset, S. K., Lo Monaco, C., Murata, A., Pérez, F. F., Pfeil, B., Schirnick, C., Steinfeldt, R., Suzuki, T., Telszewski, M., Tilbrook, B., Velo, A., and Wanninkhof, R.: GLODAPv2.2019 – an update of GLODAPv2, Earth Syst. Sci. Data, 11, 1437–1461, https://doi.org/10.5194/essd-11-1437-2019, 2019.
Ostrom, N. E., Macko, S. A., Deibel, D., and Thompson, R. J.: Seasonal
variation in the stable carbon and nitrogen isotope biogeochemistry of a
coastal cold ocean environment, Geochim. Cosmochim. A., 61, 2929–2942,
https://doi.org/10.1016/S0016-7037(97)00131-2, 1997.
Pepin, P., Maillet, G., Fraser, S., Shears, T., and Redmond, G.: Optical,
chemical, and biological oceanographic conditions on the Newfoundland and
Labrador Shelf during 2011–2012, DFO Can. Sci. Advis. Sec. Res. Doc. 2013/051, v + 38 p., 2013.
Peters, B. D., Lam, P. J., and Casciotti, K. L.: Nitrogen and oxygen isotope
measurements of nitrate along the US GEOTRACES Eastern Pacific Zonal
Transect (GP16) yield insights into nitrate supply, remineralization, and
water mass transport, Mar. Chem., 201, 137–150, https://doi.org/10.1016/j.marchem.2017.09.009, 2018.
Prinsenberg, S. J. and Hamilton, J.: Monitoring the volume, freshwater and
heat fluxes passing through Lancaster sound in the Canadian arctic
archipelago, Atmos. Ocean, 43, 1–22, https://doi.org/10.3137/ao.430101, 2005.
Rafter, P. A. and Sigman, D. M.: Spatial distribution and temporal
variation of nitrate nitrogen and oxygen isotopes in the upper equatorial
Pacific Ocean, Limnol. Oceanogr. 61, 14–31, https://doi.org/10.1002/lno.10152, 2016.
Robinson, R. S., Kienast, M., Luiza Albuquerque, A., Altabet, M., Contreras,
S., De Pol Holz, R., Dubois, N., Francois, R., Galbraith, E., Hsu, T.-C.,
Ivanochko, T., Jaccard, S., Kao, S.-J., Kiefer, T., Kienast, S., Lehmann,
M., Martinez, P., McCarthy, M., Möbius, J., Pedersen, T., Quan, T. M.,
Ryabenko, E., Schmittner, A., Schneider, R., Schneider-Mor, A., Shigemitsu,
M., Sinclair, D., Somes, C., Studer, A., Thunell, R., and Yang, J.-Y: A
review of nitrogen isotopic alteration in marine sediments,
Paleoceanography, 27, PA4203, https://doi.org/10.1029/2012PA002321, 2012.
Rysgaard, S., Boone, W., Carlson, D., Sejr, M. K., Bendtsen, J.,
Juul-Pedersen, T., Lund, H., Meire, L., and Mortensen, J.: An Updated View on
Water Masses on the pan-West Greenland Continental Shelf and Their Link to
Proglacial Fjords, J. Geophys. Res.-Ocean., 125, e2019JC015564, https://doi.org/10.1029/2019JC015564, 2020.
Sherwood, G. D. and Rose, G. A.: Stable isotope analysis of some
representative fish and invertebrates of the Newfoundland and Labrador
continental shelf food web, Estuar. Coast. Shelf S., 63, 537–549,
https://doi.org/10.1016/j.ecss.2004.12.010, 2005.
Sherwood, O. A., Jamieson, R. E., Edinger, E. N., and Wareham, V. E.: Stable
C and N isotopic composition of cold-water corals from the Newfoundland and
Labrador continental slope: Examination of trophic, depth and spatial
effects, Deep-Sea Res. Pt. I, 55, 1392–1402, https://doi.org/10.1016/j.dsr.2008.05.013, 2008.
Sherwood, O. A., Lehmann, M. F., Schubert, C. J., Scott, D. B., and
McCarthy, M. D.: Nutrient regime shift in the western North Atlantic
indicated by compound-specific δ15N of deep-sea gorgonian
corals, P. Natl. Acad. Sci. USA, 108, 1011–1015, https://doi.org/10.1073/pnas.1004904108, 2011.
Sherwood, O. A., Davin, S. H., Lehmann, N., Buchwald, C., Edinger, E. N., Lehmann, M. F., and Kienast, M.: Data to accompany “Stable isotope ratios in seawater nitrate reflect the influence of Pacific water along the northwest Atlantic margin”, (Version v1) [Data set], Biogeosciences, Zenodo [data set], https://doi.org/10.5281/zenodo.5129246,
last access: 27 July 2021.
Sigman, D. M., Casciotti, K. L., Andreani, M., Barford, C., Galanter, M., and
Böhlke, J. K.: A bacterial method for the nitrogen isotopic analysis of
nitrate in seawater and freshwater, Anal. Chem., 73, 4145–4153,
https://doi.org/10.1021/ac010088e, 2001.
Sigman, D. M., Granger, J., DiFiore, P. J., Lehmann, M. M., Ho, R., Cane, G.,
and van Geen, A.: Coupled nitrogen and oxygen isotope measurements of
nitrate along the eastern North Pacific margin, Global Biogeochem. Cy.,
19, GB4022, https://doi.org/10.1029/2005GB002458, 2005.
Sigman, D. M., DiFiore, P. J., Hain, M. P., Deutsch, C., Wang, Y., Karl, D.
M., Knapp, A. N., Lehmann, M. F., and Pantoja, S.: The dual isotopes of deep
nitrate as a constraint on the cycle and budget of oceanic fixed nitrogen,
Deep-Sea Res. Pt. I, 56, 1419–1439, https://doi.org/10.1016/j.dsr.2009.04.007, 2009.
Sipler, R. E., Gong, D., Baer, S. E., Sanderson, M. P., Roberts, Q. N.,
Mulholland, M. R., and Bronk, D. A.: Preliminary estimates of the
contribution of Arctic nitrogen fixation to the global nitrogen budget,
Limnol. Oceanogr. Lett., 2, 159–166, https://doi.org/10.1002/lol2.10046, 2017.
Steele, M., Morison, J., Ermold, W., Rigor, I., Ortmeyer, M., and Shimada,
K.: Circulation of summer Pacific halocline water in the Arctic Ocean, J.
Geophys. Res.-Ocean., 109, C02027, https://doi.org/10.1029/2003JC002009, 2004.
Stramma, L., Kieke, D., Rhein, M., Schott, F., Yashayaev, I., and
Koltermann, K. P.: Deep water changes at the western boundary of the
subpolar North Atlantic during 1996 to 2001, Deep-Sea Res. Pt. I, 51,
1033–1056, https://doi.org/10.1016/j.dsr.2004.04.001, 2004.
Straneo, F. and Saucier, F.: The outflow from Hudson Strait and its
contribution to the Labrador Current, Deep-Sea Res. Pt. I, 55, 926–946,
https://doi.org/10.1016/j.dsr.2008.03.012, 2008.
Sutcliffe Jr., W. H., Loucks, R. H., Drinkwater, K. F., and Coote, A. R.:
Nutrient Flex onto the Labrador Shelf from Hudson Strait and its Biological
Consequences, Can. J. Fish. Aquat. Sci., 40, 1692–1701, https://doi.org/10.1139/f83-196, 1983.
Sutherland, D. A., Pickart, R. S., Peter Jones, E., Azetsu-Scott, K., Jane
Eert, A., and Ólafsson, J.: Freshwater composition of the waters off
southeast Greenland and their link to the Arctic Ocean, J. Geophys. Res.,
114, C05020, https://doi.org/10.1029/2008JC004808, 2009.
Top, Z., Clarke, W. B., Eismont, W. C., and Jones, E. P.: Radiogenic helium
in Baffin Bay bottom water, J. Mar. Res., 38, 435–452, 1980.
Tang, C. C., Ross, C. K., Yao, T., Petrie, B., DeTracey, B. M., and Dunlap,
E.: The circulation, water masses and sea-ice of Baffin Bay, Prog.
Oceanogr., 63, 183–228, https://doi.org/10.1016/j.pocean.2004.09.005, 2004.
Torres-Valdés, S., Tsubouchi, T., Bacon, S., Naveira-Garabato, A. C.,
Sanders, R., McLaughlin, F. A., Petrie, B., Kattner, G., Azetsu-Scott, K.,
and Whitledge, T. E.: Export of nutrients from the Arctic Ocean, J. Geophys.
Res.-Ocean., 118, 1625–1644, https://doi.org/10.1002/jgrc.20063, 2013.
Townsend, D. W., Pettigrew, N. R., Thomas, M. A., Neary, M. G.,
McGillicuddy, D. J., and Donnell, J. O.: Water masses and nutrient sources to
the Gulf of Maine, J. Mar. Res., 141, 93–122, https://doi.org/10.1357/002224015815848811, 2015.
Tremblay, J.-É., Gratton, Y., Carmack, E. C., Payne, C. D., and Price, N.
M.: Impact of the large-scale Arctic circulation and the North Water Polynya
on nutrient inventories in Baffin Bay, J. Geophys. Res., 107, https://doi.org/10.1029/2000JC000595, 2002.
Tremblay, J.-É., Anderson, L. G., Matrai, P., Coupel, P., Bélanger,
S., Michel, C., and Reigstad, M.: Global and regional drivers of nutrient
supply, primary production and CO2 drawdown in the changing Arctic Ocean,
Prog. Oceanogr., 139, 171–196, https://doi.org/10.1016/j.pocean.2015.08.009, 2015.
Tremblay, J.-É., Hattori, H., Michel, C., Ringuette, M., Mei, Z. P.,
Lovejoy, C., Fortier, L., Hobson, K. A., Amiel, D., and Cochran, K.: Trophic
structure and pathways of biogenic carbon flow in the eastern North Water
Polynya, Prog. Oceanogr., 71, 402–425, https://doi.org/10.1016/j.pocean.2006.10.006, 2006.
Trull, T. W., Davies, D., and Casciotti, K.: Insights into nutrient
assimilation and export in naturally iron-fertilized waters of the Southern
Ocean from nitrogen, carbon and oxygen isotopes, Deep-Sea Res. Pt. II, 55,
820–840, https://doi.org/10.1016/j.dsr2.2007.12.035, 2008.
Vander Zanden, M. J. and Rasmussen, J. B.: Variation in δ15N
and δ13C trophic fractionation: Implications for aquatic food
web studies, Limnol. Oceanogr., 46, 2061–2066, https://doi.org/10.4319/lo.2001.46.8.2061, 2001.
Wallace, D. W. R.: A study of the ventilation of Arctic waters using
chlorofluoromethanes as tracers, Dalhousie University, Halifax NS, Canada,
1985.
Weiss, R. F.: The solubility of nitrogen, oxygen and argon in water and
seawater, Deep-Sea Res., 17, 721–735, https://doi.org/10.1016/0011-7471(70)90037-9, 1970.
Yamamoto-Kawai, M., Carmack, E., and McLaughlin, F.: Nitrogen balance and
Arctic throughflow, Nature, 443, 43, https://doi.org/10.1038/443043a, 2006.
Yamamoto-Kawai, M., McLaughlin, F. A., Carmack, E. C., Nishino, S., and
Shimada, K.: Freshwater budget of the Canada Basin, Arctic Ocean, from
salinity, δ18O, and nutrients, J. Geophys. Res.-Ocean., 113,
C01007, https://doi.org/10.1029/2006JC003858, 2008.
Yashayaev, I. and Loder, J. W.: Recurrent replenishment of Labrador Sea
Water and associated decadal-scale variability, J. Geophys. Res.-Ocean.,
121, 8095–8114, https://doi.org/10.1002/2016JC012046, 2016.
Short summary
Pacific water flowing eastward through the Canadian Arctic plays an important role in redistributing nutrients to the northwest Atlantic Ocean. Using samples collected from northern Baffin Bay to the southern Labrador Shelf, we show that stable isotopic ratios in seawater nitrate reflect the fraction of Pacific to Atlantic water. These results provide a new framework for interpreting patterns of nitrogen isotopic variability recorded in modern and archival organic materials in the region.
Pacific water flowing eastward through the Canadian Arctic plays an important role in...
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