The potential of &amp;lt;sup&amp;gt;230&amp;lt;/sup&amp;gt;Th for detection of ocean acidification
impacts on pelagic carbonate production

Heinze, Christoph; Ilyina, Tatiana; Gehlen, Marion

doi:10.5194/bg-2017-305

Cited by 2 publications

(3 citation statements)

References 37 publications

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“…Most models (Gu & Liu, ; Rempfer et al, ; Siddall et al, , ) initiate with partition coefficients ( K d ) that were determined on the Joint Global OceanFlux Study (JGOFS) campaigns in the Pacific Ocean (Chase et al, ), but due to the large uncertainties on these observations (Chase et al, ; Chase & Anderson, ; Hayes, Anderson, Fleisher, Vivancos, et al, ; Luo & Ku, ; Roy‐Barman et al, ), the models subsequently treat the K d as tunable parameters. HAMOCC (Heinze et al, ) is the only model currently updated with the newer scavenging coefficients from the Atlantic GEOTRACES section (Hayes, Anderson, Fleisher, Huang, et al, ). In NEMO‐PISCES (Dutay et al, ; Van Hulten et al, ) and iLOVECLIM (Missiaen et al, ), the 230 Th scavenging coefficients are scaled to the particle fluxes rather than based on data from either JGOFS or GEOTRACES.…”

Section: Modeling 230th: State Of the Artmentioning

confidence: 99%

“…In this section we compare the preindustrial outputs of two GCMs (Figure ), NEMO‐PISCES (Dutay et al, ; Van Hulten et al, ) and Community Earth System Model (CESM) (Gu & Liu, ), and two models of intermediate complexity, iLOVECLIM (Missiaen et al, ) and HAMOCC (Heinze et al, , ). We evaluate the 230 Th flux to the sediments ( F ) normalized by the production of 230 Th in the overlying water column ( P ).…”

Section: Modeling 230th: State Of the Artmentioning

confidence: 99%

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²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

Costa

Hayes

Anderson

et al. 2020

Paleoceanog and Paleoclimatol

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230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (>1,000 m water depth).

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Section: Modeling 230th: State Of the Artmentioning

confidence: 99%

Section: Modeling 230th: State Of the Artmentioning

confidence: 99%

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

Costa

Hayes

Anderson

et al. 2020

Paleoceanog and Paleoclimatol

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“…We argue that vertical diffusive redistribution of 230 Th into and within the surface mixed layer is responsible for the depth dependency of dissolved 232 Th fluxes in the upper water column. An increased number of global climate models are now simulating 230 Th distributions (Gu & Liu, 2017; Heinze et al, 2018; Rempfer et al, 2017; van Hulten et al, 2018). Incorporating 232 Th into these models, which have known dust flux fields, could facilitate testing our vertical mixing hypothesis and other mechanisms for generating depth‐dependent 232 Th fluxes.…”

Section: Conclusion and Outlook For Future Workmentioning

confidence: 99%

Atmospheric Dust Inputs, Iron Cycling, and Biogeochemical Connections in the South Pacific Ocean From Thorium Isotopes

Pavia

Anderson

Winckler

et al. 2020

Global Biogeochemical Cycles

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One of the primary sources of micronutrients to the sea surface in remote ocean regions is the deposition of atmospheric dust. Geographic patterns in biogeochemical processes such as primary production and nitrogen fixation that require micronutrients like iron (Fe) are modulated in part by the spatial distribution of dust supply. Global models of dust deposition rates are poorly calibrated in the open ocean, owing to the difficulty of determining dust fluxes in sparsely sampled regions. We present new estimates of dust and Fe input rates from measurements of dissolved and particulate thorium isotopes 230 Th and 232 Th on the FS Sonne SO245 section (GEOTRACES process study GPpr09) in the South Pacific. We first discuss high-resolution upper water column profiles of Th isotopes and the implications for the systematics of dust flux reconstructions from seawater Th measurements. We find dust fluxes in the center of the highly oligotrophic South Pacific Gyre that are the lowest of any mean annual dust input rates measured in the global oceans, but that are 1-2 orders of magnitude higher than those estimated by global dust models. We also determine dust-borne Fe fluxes and reassess the importance of individual Fe sources to the surface South Pacific Gyre, finding that dust dissolution, not vertical or lateral diffusion, is the primary Fe source. Finally, we combine our estimates of Fe flux in dust with previously published cellular and enzymatic quotas to determine theoretical upper limits on annual average nitrogen fixation rates for a given Fe deposition rate.

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The potential of <sup>230</sup>Th for detection of ocean acidification impacts on pelagic carbonate production

Cited by 2 publications

References 37 publications

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

Atmospheric Dust Inputs, Iron Cycling, and Biogeochemical Connections in the South Pacific Ocean From Thorium Isotopes

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The potential of &lt;sup&gt;230&lt;/sup&gt;Th for detection of ocean acidification impacts on pelagic carbonate production

Cited by 2 publications

References 37 publications

230Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

230Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

Atmospheric Dust Inputs, Iron Cycling, and Biogeochemical Connections in the South Pacific Ocean From Thorium Isotopes

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Product

Resources

About

The potential of <sup>230</sup>Th for detection of ocean acidification impacts on pelagic carbonate production

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean