GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Global climate control on carbonate weathering intensity (2018)
    Elsevier
    In:  Chemical Geology, 527 . Art.Nr. 118762.
    Details
    Publication Date: 2021-02-08
    Description: Carbonate rocks are a peculiarity of the Earth relative to other planets in the solar system. Large terrestrial areas are covered by carbonate lithology, which actively reacts with atmospheric/biospheric CO2. Although carbonate rocks represent a major component of the global carbon cycle, their intensity and rates of chemical weathering have been overlooked. In this study, we examine three global databases of rivers and springs draining carbonate regions under various climate conditions (from −15 °C to +30 °C). Using Ca2+ + Mg2+ concentrations as a proxy, we show that carbonate weathering intensity depends upon land temperature according to a boomerang-type relationship, with maximum dissolution between 10 and 15 °C. We show that this pattern is primarily controlled by thermodynamics if we assume that the partial pressure of CO2 in soil (pCO2) increases from atmospheric-like levels under cold climate up to 100 times the present day atmospheric concentration under hot climate. The link between soil pCO2 and land temperature is still not very well known, but by using three different published predictive soil pCO2 vs. T curves, we show that the boomerang shape can be, at least qualitatively, reproduced. This study shows that more data on carbonate weathering in various environments are needed to predict with more accuracy the role that carbonate lithologies and overlying ecosystems could play in the Anthropocene.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.chemgeo.2018.05.009
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
    facet.materialart.
    Unknown
    Orography-driven chemical denudation in the Lesser Antilles: Evidence for a new feed-back mechanism stabilizing atmospheric CO2 (2011)
    HighWire Press
    Details
    Publication Date: 2011-12-01
    Description: In this paper we present chemical composition data for major elements in rivers from three islands of the Lesser Antilles. The Lesser Antilles are a tropical volcanic subduction arc and are characterized by steep gradients of relief, bedrock age and precipitation. They constitute a natural laboratory where the response of the weathering engine to large variations of runoff can be understood. Data indicate that the Lesser Antilles are characterized by extremely variable chemical weathering (40-430 t/km2/a) and CO2 consumption (300-3500.103 mol/km2/a) rates, amongst the highest found on Earth and consistent with the previous studies on the weathering of volcanic rock. A noteworthy observation is that, along the runoff gradient, concentrations of rock-derived solutes do not follow a pure dilution law and that a buffering mechanism exists stabilizing solute concentrations. As a result concentrations vary much less than runoff and chemical weathering rates are mainly controlled by runoff. Precipitation patterns in the Lesser Antilles are essentially orographic and controlled by the adiabatic decompression of the water-saturated Atlantic air masses. The production of acidity by volcanic degassing is an additional factor that modulates the runoff effect. Two main conclusions can be drawn from this study. First, chemical weathering fluxes of oceanic islands are strongly dependent upon relief repartition, which cautions the use of regional mean values to compare volcanic islands. Second, volcanic activity in the Lesser Antilles subduction arc, by creating relief, promotes high orographic precipitation and/or infiltration regimes, that in turn results in elevated chemical weathering and atmospheric CO2 consumption fluxes. This feedback mechanism, implying mainly precipitation and relief, is proposed to act in complement to the temperature-related feedback proposed by previous authors for stabilizing the atmospheric CO2 content of the atmosphere in response to volcanic CO2 degassing. This study highlights the importance of the water cycle in controlling chemical weathering of volcanic arc islands and associated CO2 consumption rates.
    Print ISSN: 0002-9599
    Electronic ISSN: 1945-452X
    Topics: Geosciences
    Published by HighWire Press on behalf of The American Journal of Science.
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Developing boron isotopes to elucidate shale weathering in the critical zone (2021)
    Elsevier
    In:  EPIC3Chemical Geology, Elsevier, 559, pp. 119900
    Details
    Publication Date: 2021-02-22
    Description: To further develop boron isotopes as a tool for understanding shale weathering, we explored patterns of boron concentrations and isotopes across the forested Susquehanna Shale Hills Critical Zone Observatory (CZO). We present boron measurements for all watershed components that provided a foundation for examining water-rock interactions in a shale dominated watershed, including water compartments (e.g., precipitation, stream water, groundwater) and solid compartments (e.g., soil, bedrock, stream sediments, suspended load, and leaf litter). Results show boron isotopes (δ11B) in the bedrock (− 4.6‰) and soil (− 5.9 to - 4.2‰) were very similar. All waters were enriched in 11B by comparison: precipitation (7.2 to 22.6‰), stream (10.3 to 15.5‰), and groundwater (2.2 to 17.4‰). Modeling revealed that isotopic fractionation observed in the surface water and groundwater could mainly be explained by water-rock interactions including clay mineral dissolution (e.g., chlorite) and coprecipitation/adsorption processes (e.g., coatings on illite particles), likely in the near surface soils (~2 m deep). We found that leaching, the loss of boron from vegetation to stream water, plays a secondary role. Specifically, such leaching likely contributes the equivalent of 10 to 26% of the B fluxes from the watershed outlet. Boron mass balance between bedrock and precipitation inputs and the exported flux of dissolved and solid pools identified a “missing” isotopically light solid flux (δ11B of −12.2 ± 5.3‰ at ~4.4 ± 3.8 mol/ha/y of B; uncertainty reported as 2 SD). We did not sample any pool with this isotopic signature. Here our data suggest the composition of this pool is more likely related to precipitation of secondary clays rather than adsorption or (co)precipitation on Fe oxides. We propose two hypotheses to explain the missing light B pool: 1) a significant portion of the particles carrying the missing 10B are not sampled because they enter groundwater at depth and are transported out of the catchment under the stream; and/or 2) the inputs and outputs of boron are not operating at steady state in the catchment today, suggesting that the missing boron particles were lost in the past in proportions higher than today. When this B budget is paired with studies of δ26Mg and δ56Fe from Shale Hills, both of which also show missing isotopic pools, the pattern indicates a fundamental gap in understanding of shale weathering. We concluded that light B particles, presumably generated in the upper soils, are likely transported deep beneath the surface in the groundwater system or episodically in the past through riverine fluxes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 4
    facet.materialart.
    Unknown
    Predominant floodplain over mountain weathering of Himalayan sediments (Ganga basin) (2012)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 84 (2012): 410-432, doi:10.1016/j.gca.2012.02.001.
    Description: We present an extensive river sediment dataset covering the Ganga basin from the Himalayan front downstream to the Ganga mainstream in Bangladesh. These sediments were mainly collected over several monsoon seasons and include depth profiles of suspended particles in the river water column. Mineral sorting is the first order control on the chemical composition of river sediments. Taking into account this variability we show that sediments become significantly depleted in mobile elements during their transit through the floodplain. By comparing sediments sampled at the Himalayan front with sediments from the Ganga mainstream in Bangladesh it is possible to budget weathering in the floodplain. Assuming a steady state weathering regime in the floodplain, the weathering of Himalayan sediments in the Gangetic floodplain releases ca. (189 ± 92)109 and (69 ± 22)109 moles/yr of carbonate bound Ca and Mg to the dissolved load, respectively. Silicate weathering releases (53 ± 18)109 and (42 ± 13)109 moles/yr of Na and K while the release of silicate Mg and Ca is substantially lower, between ca. 0 and 20109 moles/yr. Additionally, we show that sediment hydration, [H2O+], is a sensitive tracer of silicate weathering that can be used in continental detrital environments, such as the Ganga basin. Both [H2O+] content and the D/H isotopic composition of sediments increases during floodplain transfer in response to mineral hydrolysis and neoformations associated to weathering reactions. By comparing the chemical composition of river sediments across the floodplain with the composition of the eroded Himalayan source rocks, we suggest that the floodplain is the dominant location of silicate weathering for Na, K and [H2O+]. Overall this work emphasizes the role of the Gangetic floodplain in weathering Himalayan sediments. It also demonstrates how detrital sediments can be used as weathering tracers if mineralogical and chemical sorting effects are properly taken into account.
    Description: This work was supported by INSU program “Relief de la Terre” and ANR Calimero. Valier Galy was supported by the U.S. National Science Fundation (Grant OCE-0851015).
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 5
    facet.materialart.
    Unknown
    Erosion of organic carbon in the Arctic as a geological carbon dioxide sink (2015)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 524 (2015): 84-87, doi:10.1038/nature14653.
    Description: Soils of the northern high latitudes store carbon over millennial timescales (103 yrs) and contain approximately double the carbon stock of the atmosphere1-3. Warming and associated permafrost thaw can expose soil organic carbon and result in mineralisation and carbon dioxide (CO2) release4-6. However, some of this soil organic carbon may be eroded and transferred to rivers7-9. If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (〉104 yrs), geological CO2 sink8-10. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify POC source in the Mackenzie River, the main sediment supplier to the Arctic Ocean11,12 and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios 26 to correct for rock-derived POC10,13,14. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5800±800 yr, much older than large tropical rivers13,14. Based on the measured biospheric POC content and variability in annual sediment yield15, we calculate a biospheric POC flux of 𝟐. 𝟐𝟐−𝟎𝟎.𝟗𝟗 +𝟏𝟏.𝟑𝟑 TgC yr-1 from the Mackenzie River, three times the CO2 drawdown by silicate weathering16. Offshore we find evidence for efficient terrestrial organic carbon burial over the Holocene, suggesting that erosion of organic carbon-rich, high latitude soils may result in a significant geological CO2 sink.
    Description: Radiocarbon measurements were funded by the Natural Environment Research Council (NERC), UK (Allocation 1611.0312) to R.G.H and C.B. Fieldwork was funded by CNRS (OXYMORE and CANNIBALT) to J.G. and R.G.H., the Woods Hole Oceanographic Institution Arctic Research Initiative to V.G. and an Early Career Research Grant by the British Society for Geomorphology to R.G.H. V.G. was supported by the US National Science Foundation (OCE-0928582) and H.C. by a Royal Society University Fellowship.
    Description: 2016-02-05
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 6
    facet.materialart.
    Unknown
    A Rouse-based method to integrate the chemical composition of river sediments : application to the Ganga basin (2011)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2011. 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 116 (2011): F04012, doi:10.1029/2010JF001947.
    Description: The Ganga River is one of the main conveyors of sediments produced by Himalayan erosion. Determining the flux of elements transported through the system is essential to understand the dynamics of the basin. This is hampered by the chemical heterogeneity of sediments observed both in the water column and under variable hydrodynamic conditions. Using Acoustic Doppler Current Profiler (ADCP) acquisitions with sediment depth profile sampling of the Ganga in Bangladesh we build a simple model to derive the annual flux and grain size distributions of the sediments. The model shows that ca. 390 (±30) Mt of sediments are transported on average each year through the Ganga at Haring Bridge (Bangladesh). Modeled average sediment grain size parameters D50 and D84 are 27 (±4) and 123 (±9) μm, respectively. Grain size parameters are used to infer average chemical compositions of the sediments owing to a strong grain size chemical composition relation. The integrated sediment flux is characterized by low Al/Si and Fe/Si ratios that are close to those inferred for the Himalayan crust. This implies that only limited sequestration occurs in the Gangetic floodplain. The stored sediment flux is estimated to c.a. 10% of the initial Himalayan sediment flux by geochemical mass balance. The associated, globally averaged sedimentation rates in the floodplain are found to be ca. 0.08 mm/yr and yield average Himalayan erosion rate of ca. 0.9 mm/yr. This study stresses the need to carefully address the average composition of river sediments before solving large-scale geochemical budgets.
    Description: This work was supported by INSU program “Relief de la Terre” and ANR Calimero. Valier Galy was supported by the U.S. National Science Foundation (grant OCE‐0851015).
    Keywords: Ganga ; Himalaya ; Chemical composition ; Floodplain ; River sediments
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/plain
    Format: application/vnd.ms-excel
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 7
    facet.materialart.
    Unknown
    Steering operational synergies in terrestrial observation networks : opportunity for advancing Earth system dynamics modelling (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 Earth System Dynamics 9 (2018): 593-609, doi:10.5194/esd-9-593-2018.
    Description: Advancing our understanding of Earth system dynamics (ESD) depends on the development of models and other analytical tools that apply physical, biological, and chemical data. This ambition to increase understanding and develop models of ESD based on site observations was the stimulus for creating the networks of Long-Term Ecological Research (LTER), Critical Zone Observatories (CZOs), and others. We organized a survey, the results of which identified pressing gaps in data availability from these networks, in particular for the future development and evaluation of models that represent ESD processes, and provide insights for improvement in both data collection and model integration. From this survey overview of data applications in the context of LTER and CZO research, we identified three challenges: (1) widen application of terrestrial observation network data in Earth system modelling, (2) develop integrated Earth system models that incorporate process representation and data of multiple disciplines, and (3) identify complementarity in measured variables and spatial extent, and promoting synergies in the existing observational networks. These challenges lead to perspectives and recommendations for an improved dialogue between the observation networks and the ESD modelling community, including co-location of sites in the existing networks and further formalizing these recommendations among these communities. Developing these synergies will enable cross-site and cross-network comparison and synthesis studies, which will help produce insights around organizing principles, classifications, and general rules of coupling processes with environmental conditions.
    Description: Financial support from NSF, NEON, LTER, and CZO made this collaboration possible. Henry W. Loescher and Samantha R. Weintraub acknowledge the National Science Foundation (NSF) for ongoing support. NEON is a project sponsored by the NSF and managed under cooperative support agreement (EF-1029808) to Battelle. Roland Baatz, Steffen Zacharias, and Ingolf Kühn acknowledge the European Union’s Horizon 2020 research and innovation program grant agreement no. 654359 (eLTER Horizon 2020). Furthermore the work was supported by the Terrestrial Environmental Observatories (TERENO), which is a joint collaboration program involving several Helmholtz Research Centers in Germany.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 8
    facet.materialart.
    Unknown
    Sulfur isotopes in rivers : insights into global weathering budgets, pyrite oxidation, and the modern sulfur cycle (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 Earth and Planetary Science Letters 496 (2018): 168-177, doi:10.1016/j.epsl.2018.05.022.
    Description: The biogeochemical sulfur cycle is intimately linked to the cycles of carbon, iron, and oxygen, and plays an important role in global climate via weathering reactions and aerosols. However, many aspects of the modern budget of the global sulfur cycle are not fully understood. We present new δ34S measurements on sulfate from more than 160 river samples from different geographical and climatic regions—more than 46% of the world’s freshwater flux to the ocean is accounted for in this estimate of the global riverine sulfur isotope budget. These measurements include major rivers and their tributaries, as well as time series, and are combined with previously published data to estimate the modern flux-weighted global riverine δ34S as 4.4 ± 4.5 ‰ (V-CDT), and 4.8 ± 4.9 ‰ when the most polluted rivers are excluded. Combined with major anion and cation concentrations, the sulfur isotope data allow us to tease apart the relative contributions of different processes to the modern riverine sulfur budget, resulting in new estimates of the flux of riverine sulfate due to the oxidative weathering of pyrites (1.3 ± 0.2 Tmol S/y) and the weathering of sedimentary sulfate minerals (1.5 ± 0.2 Tmol S/y). These data indicate that previous estimates of the global oxidative weathering of pyrite have been too low by a factor of two. As pyrite oxidation coupled to carbonate weathering can act as a source of CO2 to the atmosphere, this global pyrite weathering budget implies that the global CO2 weathering sink is overestimated. Furthermore, the large range of sulfur isotope ratios in modern rivers indicates that secular changes in the lithologies exposed to weathering through time could play a major role in driving past variations in δ34S of seawater.
    Description: This research was funded by a Foster and Coco Stanback postdoctoral fellowship and a Marie Curie Career Integration Grant (CIG14-631752) to AB. JFA acknowledges the support of NSF-OCE grant 1340174 and NSF-EAR grant 1349858. WF acknowledges the support of a grant from the David and Lucile Packard Foundation.
    Keywords: Sulfur ; Rivers ; Weathering ; Pyrite
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...