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  • 2015-2019  (6)
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  • 1
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    Analysis of brGDGTs as tracers for soil organic carbon in the Madre de Dios River system (2019)
    PANGAEA
    In:  Supplement to: Kirkels, Frédérique M S A; Ponton, Camilo; Galy, Valier; West, A Joshua; Feakins, Sarah J; Peterse, Francien (2019): From Andes to Amazon: assessing branched tetraether lipids as tracers for soil Organic Carbon in the Madre de Dios River system. Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2019JG005270
    Details
    Publication Date: 2023-01-13
    Description: Geochemical data, brGDGT fractions and calculated indices for soils and river samples during the wet and dry season in the Madre de Dios catchment, Peru.
    Keywords: altitudinal transect; Amazon headwaters; Branched and isoprenoid tetraether index; Branched GDGTs; Branched glycerol dialkyl glycerol tetraether, Ia, fractional abundance; Branched glycerol dialkyl glycerol tetraether, Ib, fractional abundance; Branched glycerol dialkyl glycerol tetraether, Ic, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIa, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIa', fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIb, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIb', fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIc, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIc', fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIIa, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIIa', fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIIb, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIIb', fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIIc, fractional abundance; Branched glycerol dialkyl glycerol tetraether, IIIc', fractional abundance; Calculated from linear regression; Carbon, organic, total; Cyclization ratio of branched tetraethers; Degree of cyclisation; derived from pH; ELEVATION; in-situ production; Isomer ratio; LATITUDE; LONGITUDE; Madre_de_Dios_River_System; Madre de Dios River; MULT; Multiple investigations; Peru; pH, soil; Sample comment; Sample ID; soil inputs; Specific surface area; Sum branched glycerol dialkyl glycerol tetraether, per unit sediment mass; Suspended sediment concentration; Temperature, annual mean
    Type: Dataset
    Format: text/tab-separated-values, 2233 data points
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    DATA PANGAEA
  • 2
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    Dual isotope evidence for sedimentary integration of plant wax biomarkers across an Andes-Amazon elevation transect (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 Geochimica et Cosmochimica Acta 242 (2018): 64-81, doi:10.1016/j.gca.2018.09.007.
    Description: Tropical montane regions tend to have high rates of precipitation, biological production, erosion, and sediment export, which together move material off the landscape and toward sedimentary deposits downstream. Plant wax biomarkers can be used to investigate sourcing of organic matter and are often used as proxies to reconstruct past climate and environment in sedimentary deposits. To understand how plant waxes are sourced within a wet, tropical montane catchment, we measure the stable C and H isotope composition (δ13C and δD) of n-alkanes and n-alkanoic acids in soils along an elevation transect and from sediments within the Madre de Dios River network along the eastern flank of the Peruvian Andes, draining an area of 75,400 km2 and 6 km of elevation. Soils yield systematic trends in plant wax δ13C (+1.75 and +1.31‰ km−1, for the C29n-alkanes and C30n-alkanoic acids respectively in the mineral horizon) and δD values (−10 and −12‰ km−1, respectively) across a 3.5 km elevation transect, which approximates trends previously reported from canopy leaves, though we find offsets between δ13C values in plants and soils. River suspended sediments generally follow soil isotopic gradients defined by catchment elevations (δ13C: +1.03 and +0.99‰ km−1 and δD: −10 to −7‰ km−1, for the C29n-alkanes and C30n-alkanoic acids respectively) in the wet season, with a lowering in the dry season that is less well-constrained. In a few river suspended sediments, petrogenic contributions and depth-sorting influence the n-alkane δ13C signal. Our dual isotope, dual compound class and seasonal sampling approach reveals no Andean-dominance in plant wax export, and instead that the sourcing of plant waxes in this very wet, forested catchment approximates that expected for spatial integration of the upstream catchment, thus with a lowland dominance on areal basis, guiding paleoenvironmental reconstructions in tropical montane regions. The dual isotope approach provides a cross-check on the altitudinal signals and can resolve ambiguity such as might be associated with vegetation change or aridity in paleoclimate records. Further, the altitude effect encoded within plant waxes presents a novel dual-isotope biomarker approach to paleoaltimetry.
    Description: This material is based upon work supported by the US National Science Foundation under Grant No. EAR-1227192 to A.J.W and S.J.F for the river work.
    Keywords: Plant wax ; Leaf wax ; Biomarker ; Hydrogen isotope ; Carbon isotope ; Andes ; Amazon ; Paleoaltimetry ; Source-to-sink
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 3
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    Reconciling drainage and receiving basin signatures of the Godavari River system (2018)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 15 (2018): 3357-3375, doi:10.5194/bg-15-3357-2018.
    Description: The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OCterr; 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OCterr is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic matter (OM) exported by the fluvial system and establish links to sedimentary records accumulating on its adjacent continental margin, the stable and radiogenic isotopic composition of bulk OC, abundance and distribution of long-chain fatty acids (LCFAs), sedimentological properties (e.g. grain size, mineral surface area, etc.) of fluvial (riverbed and riverbank) sediments and soils from the Godavari basin were analysed and these characteristics were compared to those of a sediment core retrieved from the continental slope depocenter. Results show that river sediments from the upper catchment exhibit higher total organic carbon (TOC) contents than those from the lower part of the basin. The general relationship between TOC and sedimentological parameters (i.e. mineral surface area and grain size) of the sediments suggests that sediment mineralogy, largely driven by provenance, plays an important role in the stabilization of OM during transport along the river axis, and in the preservation of OM exported by the Godavari to the Bay of Bengal. The stable carbon isotopic (δ13C) characteristics of river sediments and soils indicate that the upper mainstream and its tributaries drain catchments exhibiting more 13C enriched carbon than the lower stream, resulting from the regional vegetation gradient and/or net balance between the upper (C4-dominated plants) and lower (C3-dominated plants) catchments. The radiocarbon contents of organic carbon (Δ14COC) in deep soils and eroding riverbanks suggests these are likely sources of "old" or pre-aged carbon to the Godavari River that increasingly dominates the late Holocene portion of the offshore sedimentary record. While changes in water flow and sediment transport resulting from recent dam construction have drastically impacted the flux, loci, and composition of OC exported from the modern Godavari basin, complicating reconciliation of modern-day river basin geochemistry with that recorded in continental margin sediments, such investigations provide important insights into climatic and anthropogenic controls on OC cycling and burial.
    Description: This project was supported by the Swiss National Science Foundations (“CAPS LOCK” grant no. 200021-140850 and “CAPS-LOCK2” grant no. 200021-163162). Francien Peterse received funding from NWO-Veni grant (grant no. 863.13.016). Liviu Giosan thanks grants from the National Science Foundation (OCE-0841736) and Woods Hole Oceanographic Institution.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
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    Source to sink : evolution of lignin composition in the Madre de Dios River system with connection to the Amazon basin and offshore (2016)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2016. 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: Biogeosciences 121 (2016): 1316–1338, doi:10.1002/2016JG003323.
    Description: While lignin geochemistry has been extensively investigated in the Amazon River, little is known about lignin distribution and dynamics within deep, stratified river channels or its transformations within soils prior to delivery to rivers. We characterized lignin phenols in soils, river particulate organic matter (POM), and dissolved organic matter (DOM) across a 4 km elevation gradient in the Madre de Dios River system, Peru, as well as in marine sediments to investigate the source-to-sink evolution of lignin. In soils, we found more oxidized lignin in organic horizons relative to mineral horizons. The oxidized lignin signature was maintained during transfer into rivers, and lignin was a relatively constant fraction of bulk organic carbon in soils and riverine POM. Lignin in DOM became increasingly oxidized downstream, indicating active transformation of dissolved lignin during transport, especially in the dry season. In contrast, POM accumulated undegraded lignin downstream during the wet season, suggesting that terrestrial input exceeded in-river degradation. We discovered high concentrations of relatively undegraded lignin in POM at depth in the lower Madre de Dios River in both seasons, revealing a woody undercurrent for its transfer within these deep rivers. Our study of lignin evolution in the soil-river-ocean continuum highlights important seasonal and depth variations of river carbon components and their connection to soil carbon pools, providing new insights into fluvial carbon dynamics associated with the transfer of lignin biomarkers from source to sink.
    Description: U.S. National Science Foundation Grant Number: 1227192; National Program on Key Basic Research Project Grant Number: 2015CB954201; National Natural Science Foundation of China Grant Number: 41422304; Natural Environment Research Council NE/F002149/1 Grant Number: FT110100457; European Union Marie Curie Fellowship Grant Number: FP7-2012-329360; NSF Grant Number: OCE-0934073
    Description: 2016-11-21
    Keywords: Lignin phenols ; Dissolved organic matter (DOM) ; Particulate organic matter (POM) ; Andes ; Amazon ; Depth profile
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
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    Short communication : Massive erosion in monsoonal central India linked to late Holocene land cover degradation (2018)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Earth Surface Dynamics 5 (2017): 781-789, doi:10.5194/esurf-5-781-2017.
    Description: Soil erosion plays a crucial role in transferring sediment and carbon from land to sea, yet little is known about the rhythm and rates of soil erosion prior to the most recent few centuries. Here we reconstruct a Holocene erosional history from central India, as integrated by the Godavari River in a sediment core from the Bay of Bengal. We quantify terrigenous fluxes, fingerprint sources for the lithogenic fraction and assess the age of the exported terrigenous carbon. Taken together, our data show that the monsoon decline in the late Holocene significantly increased soil erosion and the age of exported organic carbon. This acceleration of natural erosion was later exacerbated by the Neolithic adoption and Iron Age extensification of agriculture on the Deccan Plateau. Despite a constantly elevated sea level since the middle Holocene, this erosion acceleration led to a rapid growth of the continental margin. We conclude that in monsoon conditions aridity boosts rather than suppresses sediment and carbon export, acting as a monsoon erosional pump modulated by land cover conditions.
    Description: This study was supported by grants from Woods Hole Oceanographic Institution, the National Science Foundation (OCE-0841736 and OCE-0623766) and Swiss National Science Foundation (“CAPS LOCK” 200021-140850 and “CAPS-LOCK2” 200021-163162).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
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    Sustained wood burial in the Bengal Fan over the last 19 My (2019)
    National Academy of Sciences
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © National Academy of Sciences, 2019. This article 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 116(45), (2019): 22518-22525, doi:10.1073/pnas.1913714116.
    Description: The Ganges–Brahmaputra (G-B) River system transports over a billion tons of sediment every year from the Himalayan Mountains to the Bay of Bengal and has built the world’s largest active sedimentary deposit, the Bengal Fan. High sedimentation rates drive exceptional organic matter preservation that represents a long-term sink for atmospheric CO2. While much attention has been paid to organic-rich fine sediments, coarse sediments have generally been overlooked as a locus of organic carbon (OC) burial. However, International Ocean Discovery Program Expedition 354 recently discovered abundant woody debris (millimeter- to centimeter-sized fragments) preserved within the coarse sediment layers of turbidite beds recovered from 6 marine drill sites along a transect across the Bengal Fan (∼8°N, ∼3,700-m water depth) with recovery spanning 19 My. Analysis of bulk wood and lignin finds mostly lowland origins of wood delivered episodically. In the last 5 My, export included C4 plants, implying that coarse woody, lowland export continued after C4 grassland expansion, albeit in reduced amounts. Substantial export of coarse woody debris in the last 1 My included one wood-rich deposit (∼0.05 Ma) that encompassed coniferous wood transported from the headwaters. In coarse layers, we found on average 0.16 weight % OC, which is half the typical biospheric OC content of sediments exported by the modern G-B Rivers. Wood burial estimates are hampered by poor drilling recovery of sands. However, high-magnitude, low-frequency wood export events are shown to be a key mechanism for C burial in turbidites.
    Description: This work was funded by National Science Foundation Grants OCE-1401217 and COL-T354A55 to S.J.F. and OCE-1400805 to V.G. Graduate student participation in the project received support from University of Southern California Provost’s Fellowship to H.L. Samples were provided by the International Ocean Discovery Program. We are grateful for the efforts of the Expedition 354 Science Party, Carl Johnson, and Zongguang Liu. C.F.-L. and A.G. were supported by IODP-France. We thank Colin Osborne and Maria Vorontsova for helpful discussions.
    Description: 2020-04-21
    Keywords: carbon cycle ; wood ; lignin ; Himalaya ; Bengal Fan
    Repository Name: Woods Hole Open Access Server
    Type: Article
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