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  • 1
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    Relationships between grain size and organic carbon 14C heterogeneity in continental margin sediments (2019)
    Elsevier
    In:  Earth and Planetary Science Letters, 505 . pp. 76-85.
    Details
    Publication Date: 2022-01-31
    Description: Highlights • Continental margin-scale spatial variability in C values among grain size fractions is presented. • Two different hydrodynamic modes influencing in 14C heterogeneity are identified. • A new index (H14 index) is defined to describe overall 14C heterogeneity within marine surface sedimentary OC. Abstract The deposition and long-term burial of sedimentary organic matter (OM) on continental margins comprises a fundamental component of the global carbon cycle. A key unknown in interpretation of carbon isotope records of sedimentary OM is the extent to which OM accumulating in continental shelf and slope sediments is influenced by dispersal and redistribution processes. Here, we present results from an extensive survey of organic carbon (OC) characteristics of grain size fractions (ranging from 〈20 to 250 μm) retrieved from Chinese marginal sea surface sediments in order to assess the extent to which the abundance and isotope composition of OM in shallow shelf seas is influenced by hydrodynamic processes. Our findings show that contrasting relationships exist between 14C contents of OC and grain size in surface sediments associated with two different hydrodynamic modes, suggesting that transport pathways and mechanisms imparted by the different hydrodynamic conditions exert a strong influence on 14C contents of OM in continental shelf sediments. In deeper regions and erosional areas, we infer that bedload transport exerts the strongest influence on (decreases) OC 14C contents of the coarser fraction, while resuspension processes induce OC 14C depletion of intermediate grain size fractions in shallow inner-shelf settings. We use the inter-fraction spread in 14C values, defined here as 14H , to argue that the hydrodynamic processes amplify overall 14C heterogeneity within corresponding bulk sediment samples. The magnitude and footprint of this heterogeneity carries implications for our understanding of carbon cycling in shallow marginal seas.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2018.10.013
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Long-chain diols in rivers: distribution and potential biological sources (2018)
    In:  EPIC3Biogeosciences, 15(13), pp. 4147-4161, ISSN: 1726-4189
    Details
    Publication Date: 2018-09-10
    Description: Long-chain diols (LCDs) occur widespread in marine environments and also in lakes and rivers. Transport of LCDs from rivers may impact the distribution of LCDs in coastal environments, however relatively little is known about the distribution and biological sources of LCDs in river systems. In this study, we investigated the distribution of LCDs in suspended particulate matter (SPM) of three river systems (Godavari, Danube, and Rhine) in relation with precipitation, temperature, and source catchments. The dominant long-chain diol is the C32 1,15-diol followed by the C30 1,15-diol in all studied river systems. In regions influenced by marine waters, such as delta systems, the fractional abundance of the C30 1,15-diol is substantially higher than in the river itself, suggesting different LCD producers in marine and freshwater environments. A change in the LCD distribution along the downstream transects of the rivers studied was not observed. However, an effect of river flow is observed; i.e., the concentration of the C32 1,15-diol is higher in stagnant waters such as reservoirs and during seasons with river low stands. A seasonal change in the LCD distribution was observed in the Rhine, likely due to a change in the producers. Eukaryotic diversity analysis by 18S rRNA gene sequencing of SPM from the Rhine showed extremely low abundances of sequences (i.e., 〈0.32% of total reads) related to known algal LCD producers. Furthermore, incubation of the river water with 13C-labeled bicarbonate did not result in 13C incorporation into LCDs. This indicates that the LCDs present are mainly of fossil origin in the fast-flowing part of the Rhine. Overall, our results suggest that the LCD producers in rivers predominantly reside in lakes or side ponds that are part of the river system.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
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    Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw (2017)
    In:  EPIC3Scientific Reports, 7, pp. 45809, ISSN: 2045-2322
    Details
    Publication Date: 2017-06-12
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    Compound-Specific Radiocarbon Measurements (2019)
    Elsevier
    In:  EPIC3Encyclopedia of Ocean Sciences, Encyclopedia of Ocean Sciences, Third Edition, Vol 1, Elsevier, 10 p., pp. 235-244, ISBN: 978-0-12-813081-0
    Details
    Publication Date: 2019-05-20
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 5
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    Multi-molecular tracers of terrestrial carbon transfer across the pan-Arctic : comparison of hydrolyzable components with plant wax lipids and lignin phenols (2015)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 12 (2015): 4841-4860, doi:10.5194/bg-12-4841-2015.
    Description: Hydrolyzable organic carbon (OC) comprises a significant component of sedimentary particulate matter transferred from land into oceans via rivers. Its abundance and nature are however not well studied in Arctic river systems, and yet may represent an important pool of carbon whose fate remains unclear in the context of mobilization and related processes associated with a changing climate. Here, we examine the molecular composition and source of hydrolyzable compounds isolated from sedimentary particles derived from nine rivers across the pan-Arctic. Bound fatty acids (b-FAs), hydroxy FAs, n-alkane-α,ω-dioic acids (DAs) and phenols were the major components released upon hydrolysis of these sediments. Among them, b-FAs received considerable inputs from bacterial and/or algal sources, whereas ω-hydroxy FAs, mid-chain substituted acids, DAs, and hydrolyzable phenols were mainly derived from cutin and suberin of higher plants. We further compared the distribution and fate of suberin- and cutin-derived compounds with those of other terrestrial biomarkers (plant wax lipids and lignin phenols) from the same Arctic river sedimentary particles and conducted a benchmark assessment of several biomarker-based indicators of OC source and extent of degradation. While suberin-specific biomarkers were positively correlated with plant-derived high-molecular-weight (HMW) FAs, lignin phenols were correlated with cutin-derived compounds. These correlations suggest that, similar to leaf-derived cutin, lignin was mainly derived from litter and surface soil horizons, whereas suberin and HMW FAs incorporated significant inputs from belowground sources (roots and deeper soil). This conclusion is supported by the negative correlation between lignin phenols and the ratio of suberin-to-cutin biomarkers. Furthermore, the molecular composition of investigated biomarkers differed between Eurasian and North American Arctic rivers: while lignin dominated in the terrestrial OC of Eurasian river sediments, hydrolyzable OC represented a much larger fraction in the sedimentary particles from Colville River. Hence, studies exclusively focusing on either plant wax lipids or lignin phenols will not be able to fully unravel the mobilization and fate of bound OC in Arctic rivers. More comprehensive, multi-molecular investigations are needed to better constrain the land–ocean transfer of carbon in the changing Arctic, including further research on the degradation and transfer of both free and bound components in Arctic river sediments.
    Description: X. Feng acknowledges support from the Chinese National Key Development Program for Basic Research (2014CB954003, 2015CB954201). The ISSS program is supported by the Knut and Alice Wallenberg Foundation, headquarters of the Russian Academy of Sciences, the Swedish Research Council, the US National Oceanic and Atmospheric Administration, the Russian Foundation of Basic Research (#13-05-12028, 13-05-12041), the Swedish Polar Research Secretariat and the Nordic Council of Ministers (Arctic Co-Op and TRI-DEFROST programs). Collection of the Mackenzie sediment samples was supported by Fisheries and Oceans Canada and Indian and Northern Affairs Canada as part of the NOGAP B.6 project. Ö. Gustafsson acknowledges an Academy Research Fellow grant from the Swedish Royal Academy of Sciences. I. P. Semiletov and O. V. Dudarev thank the Government of the Russian Federation (#2013-220-04-157) for support as well as A. I. Khanchuk personally. T. I. Eglinton acknowledges support from Swiss National Science foundation (SNF) grant no. 200021_140850, and grants OCE-9907129, OCE-0137005, and OCE-0526268 from the US National Science Foundation (NSF), the Stanley Watson Chair for Excellence in Oceanography, and ETH Zurich. J. E. Vonk is thankful for support from NWO Rubicon (#825.10.022) and Veni (#863.12.004). B. E. van Dongen is thankful for support from the UK NERC (NE/I024798/1). R. M. Holmes acknowledges support from NSF 0436118, NSF 0732555, and NSF 1107774. X. Feng thanks WHOI for a postdoctoral scholar fellowship and for postdoctoral support from ETH Zurich.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
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    Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands (2015)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of American 112 (2015): 5607-5612, doi: 10.1073/pnas.1419133112.
    Description: Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (approximately 800 to 950 CE). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands, but does not explain more pronounced and earlier societaldisruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant-wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ~200 to 500 CE, during the Terminal Preclassic and Early Classic periods. Plant-wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.
    Description: This work was partially funded by the Italian Ministry of the Environment and by the U.S. National Science Foundation Graduate Research Fellowship.
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 7
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    Global-scale evidence for the refractory nature of riverine black carbon (2018)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Nature Geoscience 11 (2018): 584-588, doi:10.1038/s41561-018-0159-8.
    Description: Wildfires and incomplete combustion of fossil fuel produce large amounts of black carbon. Black carbon production and transport are essential components of the carbon cycle. Constraining estimates of black carbon exported from land to ocean is critical, given ongoing changes in land use and climate, which affect fire occurrence and black carbon dynamics. Here, we present an inventory of the concentration and radiocarbon content (∆14C) of particulate black carbon for 18 rivers around the globe. We find that particulate black carbon accounts for about 15.8 ± 0.9% of river particulate organic carbon, and that fluxes of particulate black carbon co-vary with river-suspended sediment, indicating that particulate black carbon export is primarily controlled by erosion. River particulate black carbon is not exclusively from modern sources but is also aged in intermediate terrestrial carbon pools in several high-latitude rivers, with ages of up to 17,000 14C years. The flux-weighted 14C average age of particulate black carbon exported to oceans is 3,700 ± 400 14C years. We estimate that the annual global flux of particulate black carbon to the ocean is 0.017 to 0.037 Pg, accounting for 4 to 32% of the annually produced black carbon. When buried in marine sediments, particulate black carbon is sequestered to form a long-term sink for CO2.
    Description: A.C. acknowledges financial support from the University of Zurich Forschungskredit Fellowship and the University of Zurich (grant No. STWF-18-026). M.R., S.A. and M.S. acknowledge support from the University Research Priority Projection Global Change and Biodiversity (URPP-GCB). M.Z. acknowledges support from the National Natural Science Foundation of China (No. 41521064). T.E. acknowledges support from the Swiss National Science Foundation (“CAPS-LOCK” and “CAPS-LOCK2” #200021_140850). V.G. acknowledges financial support from an Independent Study Award from the Woods Hole Oceanographic Institution.
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 8
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    Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic : 14C characteristics of sedimentary carbon components and their environmental controls (2016)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 29 (2015): 1855–1873, doi:10.1002/2015GB005204.
    Description: Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular 14C measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C24,26,28), plant wax FAs (C24,26,28), and n-alkanes (C27,29,31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these “old” terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C16,18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in 14C, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular 14C analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.
    Description: Chinese National Key Development Program for Basic Research Grant Numbers: 2014CB954003, 2015CB954201; Knut and Alice Wallenberg Foundation; Headquarters of the Russian Academy of Sciences; Swedish Research Council; US National Oceanic and Atmospheric Administration; Russian Foundation of Basic Research Grant Numbers: (13-05-12028, 13-05-12041; Swedish Polar Research Secretariat; Nordic Council of Ministers; Government of the Russian Federation Grant Number: 2013-220-04-157; Swiss National Science foundation. Grant Number: (200021_140850 US National Science Foundation (NSF) Grant Numbers: OCE-9907129, OCE-0137005, OCE-0526268; Stanley Watson Chair for Excellence in Oceanography Grant Number: 825.10.022; ETH Zürich; NWO Rubicon; Veni Grant Number: 863.12.004; UK NERC Grant Number: NE/I024798/1; NSF. Grant Numbers: 0436118, 0732555, 1107774
    Description: 2016-05-02
    Keywords: Compound-specific radiocarbon analysis ; Terrestrial carbon markers ; Pan-arctic rivers ; Diacids ; Lignin ; Plant wax lipids
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 9
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    Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations (2017)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Carbon Balance and Management 12 (2017): 10, doi:10.1186/s13021-017-0077-x.
    Description: Determining national carbon stocks is essential in the framework of ongoing climate change mitigation actions. Presently, assessment of carbon stocks in the context of greenhouse gas (GHG)-reporting on a nation-by-nation basis focuses on the terrestrial realm, i.e., carbon held in living plant biomass and soils, and on potential changes in these stocks in response to anthropogenic activities. However, while the ocean and underlying sediments store substantial quantities of carbon, this pool is presently not considered in the context of national inventories. The ongoing disturbances to both terrestrial and marine ecosystems as a consequence of food production, pollution, climate change and other factors, as well as alteration of linkages and C-exchange between continental and oceanic realms, highlight the need for a better understanding of the quantity and vulnerability of carbon stocks in both systems. We present a preliminary comparison of the stocks of organic carbon held in continental margin sediments within the Exclusive Economic Zone of maritime nations with those in their soils. Our study focuses on Namibia, where there is a wealth of marine sediment data, and draws comparisons with sediment data from two other countries with different characteristics, which are Pakistan and the United Kingdom. Results indicate that marine sediment carbon stocks in maritime nations can be similar in magnitude to those of soils. Therefore, if human activities in these areas are managed, carbon stocks in the oceanic realm—particularly over continental margins—could be considered as part of national GHG inventories. This study shows that marine sediment organic carbon stocks can be equal in size or exceed terrestrial carbon stocks of maritime nations. This provides motivation both for improved assessment of sedimentary carbon inventories and for reevaluation of the way that carbon stocks are assessed and valued. The latter carries potential implications for the management of human activities on coastal environments and for their GHG inventories.
    Description: We acknowledge research support from ETH Zurich and the Swiss National Science Foundation.
    Keywords: Carbon stocks ; Sediments ; Oceans ; Climate change ; Exclusive Economic Zone ; Carbon inventory
    Repository Name: Woods Hole Open Access Server
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  • 10
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    Biological and physical controls on the flux and characteristics of sinking particles on the Northwest Atlantic margin (2017)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 4539–4553, doi:10.1002/2016JC012549.
    Description: Biogenic matter characteristics and radiocarbon contents of organic carbon (OC) were examined on sinking particle samples intercepted at three nominal depths of 1000 m, 2000 m, and 3000 m (∼50 m above the seafloor) during a 3 year sediment trap program on the New England slope in the Northwest Atlantic. We have sought to characterize the sources of sinking particles in the context of vertical export of biogenic particles from the overlying water column and lateral supply of resuspended sediment particles from adjacent margin sediments. High aluminum (Al) abundances and low OC radiocarbon contents indicated contributions from resuspended sediment which was greatest at 3000 m but also significant at shallower depths. The benthic source (i.e., laterally supplied resuspended sediment) of opal appears negligible based on the absence of a correlation with Al fluxes. In comparison, CaCO3 fluxes at 3000 m showed a positive correlation with Al fluxes. Benthic sources accounted for 42 ∼ 63% of the sinking particle flux based on radiocarbon mass balance and the relationship between Al flux and CaCO3 flux. Episodic pulses of Al at 3000 m were significantly correlated with the near-bottom current at a nearby hydrographic mooring site, implying the importance of current variability in lateral particle transport. However, Al fluxes at 1000 m and 2000 m were coherent but differed from those at 3000 m, implying more than one mode of lateral supply of particles in the water column.
    Description: NSF Ocean Sciences Chemical Oceanography program Grant Numbers: OCE-0425677, OCE-0851350; Ocean and Climate Change Institute of WHOI
    Description: 2017-12-01
    Keywords: Sinking particle flux ; Biological carbon pump ; Radiocarbon ; Lateral particle supply ; Sediment resuspension ; Northwest Atlantic ; Sediment trap
    Repository Name: Woods Hole Open Access Server
    Type: Article
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