Limited influence of basalt weathering inputs on the seawater neodymium isotope composition of the northern Iceland Basin

Morrison, Rachel; Waldner, A.; Hathorne, Edmund C.; Rahlf, Peer; Zieringer, Moritz; Montagna, Paolo; Colin, Christophe; Frank, Norbert

doi:10.1016/j.chemgeo.2018.10.019

Cited by 10 publications

(6 citation statements)

References 65 publications

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“…The [Nd] and ε Nd observations used in this study consist of the following three datasets: (i) the pre-GEOTRACES compilation of Nd and ε Nd data by van de Flierdt et al (2016a), (ii) the GEOTRACES Intermediate Data Product 2017 (IDP17; Schlitzer et al, 2018) (including specifically Nd-linked publications; Stichel et al, 2012aStichel et al, , b, 2015Garcia-Solsona et al, 2014;Basak et al, 2015;Fröllje et al, 2016;Lambelet et al, 2016Lambelet et al, , 2018Behrens et al, 2018a, b), and (iii) our post-IDP17 compilation of data from the Indian Ocean (Amakawa et al, 2019), the Barents Sea (Laukert et al, 2018;Laukert et al, 2019), the northern Iceland Basin (Morrison et al, 2019), the northwestern Pacific (Che and Zhang, 2018), the Kerguelen Plateau (Grenier et al, 2018), the southeastern Atlantic Ocean (GA08, Rahlf et al, 2020;Rahlf et al, 2019;Rahlf et al, 2021;Rahlf et al, 2020), the Bay of Biscay (Dausmann et al, 2020;Dausmann et al, 2019), the western North Atlantic , the Arctic (Laukert et al, 2017;Laukert et al, 2017a, d), and the Bermuda Atlantic Time-series Study (BATS; Laukert et al, 2017;Laukert et al, 2017b, c). The spatial distribution of these observations as used in this study are shown in Fig.…”

Section: Dissolved Neodymium and ε Nd Datamentioning

confidence: 99%

GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle

et al. 2022

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Abstract. Spatially distant sources of neodymium (Nd) to the ocean that carry different isotopic signatures (εNd) have been shown to trace out major water masses and have thus been extensively used to study large-scale features of the ocean circulation both past and current. While the global marine Nd cycle is qualitatively well understood, a complete quantitative determination of all its components and mechanisms, such as the magnitude of its sources and the paradoxical conservative behavior of εNd, remains elusive. To make sense of the increasing collection of observational Nd and εNd data, in this model description paper we present and describe the Global Neodymium Ocean Model (GNOM) v1.0, the first inverse model of the global marine biogeochemical cycle of Nd. The GNOM is embedded in a data-constrained steady-state circulation that affords spectacular computational efficiency, which we leverage to perform systematic objective optimization, allowing us to make preliminary estimates of biogeochemical parameters. Owing to its matrix representation, the GNOM model is additionally amenable to novel diagnostics that allow us to investigate open questions about the Nd cycle with unprecedented accuracy. This model is open-source and freely accessible, is written in Julia, and its code is easily understandable and modifiable for further community developments, refinements, and experiments.

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Section: Dissolved Neodymium and ε Nd Datamentioning

confidence: 99%

GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle

et al. 2022

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“…The extent of these benthic exchange processes most likely depends on the reactivity and surface area of the deposited material (Howe, Piotrowski, & Rennie, ). While the reactivity strongly depends on the source, the effective surface area can be increased by nepheloid layers (Gardner et al, ) that can either increase the dissolved Nd concentration and shift the isotopic composition by particle dissolution (van de Flierdt et al, ) or contrary reduce the dissolved Nd concentration by increased scavenging (Morrison et al, ). Especially the Northwest Atlantic is a region with thick and dense benthic nepheloid layers that are presumably generated by the high surface eddy kinetic energy of the Gulf Stream (Gardner et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Especially the Northwest Atlantic is a region with thick and dense benthic nepheloid layers that are presumably generated by the high surface eddy kinetic energy of the Gulf Stream (Gardner et al, ). Nevertheless, sediment core top calibrations to seawater data yield generally good agreements (e.g., Lippold et al, ; Piotrowski et al, ; Tachikawa et al, ), but small discrepancies were also reported especially around Iceland and in parts of the abyssal Northwest Atlantic (Elmore et al, ; Pöppelmeier et al, ; Roberts et al, ), both are areas where potentially reactive material and benthic nepheloid layers are observed (Gardner et al, ; Morrison et al, ). Here, we first investigate possible mechanisms for the core top‐seawater offsets in the Northwest Atlantic and then discuss the temporal evolution thereof.…”

Section: Introductionmentioning

confidence: 99%

Influence of Ocean Circulation and Benthic Exchange on Deep Northwest Atlantic Nd Isotope Records During the Past 30,000 Years

Pöppelmeier

Blaser

Gutjahr

et al. 2019

Geochem Geophys Geosyst

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“…Here, a margin-only constrained benthic flux improves modeldata fit, resulting in a more unradiogenic NADW εNd signal of -13, which is in excellent agreement with measurements for this water mass of -13.2 (Lambelet et al, 2016), compared with -11 simulated under a seafloor-wide benthic flux. Resolving the εNd signal of modern NADW therefore primarily resides within disentangling the highly reactive and isotopically unique surface and marginal Nd fluxes (i.e., intense localised regions of boundary exchange), especially around the locations of deepwater formation, including unradiogenic inputs originating from the Canadian Shield (where εNd is -28), to localised radiogenic inputs from Icelandic basaltic rocks (where εNd is +7) (Blaser et al, 2019b;Stichel et al, 2020;Morrison et al, 2019;Lacan and Jeandel, 2005a;Lambelet et al, 2016). Furthermore, mixing of the less radiogenic southern-sourced water in the Atlantic likely also contributes to the more unradiogenic signal of NADW under a margin-only constrained benthic flux.…”

Section: 5 and Ref-sed3mentioning

confidence: 99%

Optimisation of the marine Nd isotope scheme in the ocean component of the FAMOUS general circulation model

Robinson

Ivanovic²,

Gregoire³

et al. 2022

Preprint

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Abstract. The neodymium (Nd) isotope composition (εNd) of seawater can be used to trace large-scale ocean circulation features. Yet, due to the elusive nature of marine Nd cycling, particularly in discerning non-conservative particle-seawater interactions, there remains considerable uncertainty surrounding a complete description of marine Nd budgets. Here, we present an optimisation of the Nd isotope scheme within the fast coupled atmosphere-ocean general circulation model (FAMOUS), using a statistical emulator to explore the parametric uncertainty and optimal combinations of three key model inputs relating to: (1) the efficiency of reversible scavenging, (2) the magnitude of the seafloor benthic flux, and (3) a riverine source scaling, accounting for release of Nd from river sourced particulate material. Furthermore, a suite of sensitivity tests provide insight on the regional mobilisation and spatial extent (i.e., testing a margin-constrained versus a seafloor-wide benthic flux) of certain reactive sediment components. In the calibrated scheme, the global marine Nd inventory totals 4.27 × 1012 g and has a mean residence time of 727 years. Atlantic Nd isotope distributions are represented well, and the weak sensitivity of North Atlantic Deep Water to highly unradiogenic sedimentary sources implies an abyssal benthic flux is of secondary importance in determining the water mass εNd properties under the modern vigorous circulation condition. On the other hand, Nd isotope distributions in the North Pacific are 3 to 4 εNd-units too unradiogenic compared to water measurements, and our simulations indicate that a spatially uniform flux of bulk sediment εNd does not sufficiently capture the mobile sediment components interacting with seawater. Our results of sensitivity tests suggest that there are distinct regional differences in how modern seawater acquires its εNd signal, in part relating to the complex interplay of Nd addition and water advection.

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Limited influence of basalt weathering inputs on the seawater neodymium isotope composition of the northern Iceland Basin

Cited by 10 publications

References 65 publications

GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle

GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle

Influence of Ocean Circulation and Benthic Exchange on Deep Northwest Atlantic Nd Isotope Records During the Past 30,000 Years

Optimisation of the marine Nd isotope scheme in the ocean component of the FAMOUS general circulation model

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