Quantifying lithogenic inputs to the North Pacific Ocean using the long-lived thorium isotopes

Hayes, Christopher T.; Anderson, Robert F.; Fleisher, Martin Q.; Serno, Sascha; Winckler, Gisela; Gersonde, Rainer

doi:10.1016/j.epsl.2013.09.025

Cited by 51 publications

(89 citation statements)

References 82 publications

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“…Dust fluxes reconstructed from dissolved thorium isotope concentrations in seawater from a number of INOPEX stations (Hayes et al, 2013) also correlate well with the sedimentary dust fluxes along the Southern and Kamchatka Transects (Fig. 9).…”

Section: Spatial Dust Flux Pattern In the Subarctic North Pacificmentioning

confidence: 61%

“…The consistency of the three independent geochemical tracers with each other, with previous dust flux data from the SNP based on sediment accumulation rates of quartz (Catubig et al, 1998;Kawahata et al, 2000) and 232 Th (Kohfeld and Chase, 2011), as well as independent estimates from dissolved thorium isotope concentrations in seawater (Hayes et al, 2013) and modeling studies , indicates that all three are valuable proxies to reconstruct dust input in complex settings with multiple lithogenic components contributing to marine sediments. The combination of the geochemical proxies and grain size distributions from the same sediment samples shows that information on the size-fractionation of source material and the application of sizespecific source data are crucial for quantitative reconstructions of eolian dust input in marine sediments.…”

Section: Discussionmentioning

confidence: 95%

“…Dust fluxes based on dissolved aluminum concentrations in seawater in the North Pacific (Measures et al, 2005), with a limited spatial overlap with the INOPEX cruise track, appear to yield dust fluxes that are lower by about an order of magnitude than results presented here. The discrepancy may indicate uncertainties in the estimate of the Al residence time in this region (Hayes et al, 2013). Dust input estimates based on accumulation rates of quartz (Catubig et al, 1998;Kawahata et al, 2000) and 232 Th (Kohfeld and Chase, 2011) tend to fall in the range of the INOPEX dust fluxes of ∼1-3 g/m 2 /yr.…”

Section: Spatial Dust Flux Pattern In the Subarctic North Pacificmentioning

confidence: 99%

“…A possible cause for this discrepancy could lie in difficulties faced by models in capturing the complex topography and fine-scale dust generation processes in East Asian are presented with ruby colored symbols and dashed lines. Dust flux results based on dissolved thorium concentrations in seawater from a number of INOPEX stations are shown as moss green hexagons and dashed lines (Hayes et al, 2013). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)…”

Section: Spatial Dust Flux Pattern In the Subarctic North Pacificmentioning

confidence: 99%

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Eolian dust input to the Subarctic North Pacific

Serno

Winckler

Anderson

et al. 2014

Earth and Planetary Science Letters

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Eolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high nutrient-low chlorophyll status of the Subarctic North Pacific. We map the spatial distribution of dust input using three different geochemical tracers of eolian dust, 4 He, 232 Th and rare earth elements, in combination with grain size distribution data, from a set of core-top sediments covering the entire Subarctic North Pacific. Using the suite of geochemical proxies to fingerprint different lithogenic components, we deconvolve eolian dust input from other lithogenic inputs such as volcanic ash, ice-rafted debris, riverine and hemipelagic input. While the open ocean sites far away from the volcanic arcs are dominantly composed of pure eolian dust, lithogenic components other than eolian dust play a more crucial role along the arcs. In sites dominated by dust, eolian dust input appears to be characterized by a nearly uniform grain size mode at ∼4 μm.Applying the 230 Th-normalization technique, our proxies yield a consistent pattern of uniform dust fluxes of 1-2 g/m 2 /yr across the Subarctic North Pacific. Elevated eolian dust fluxes of 2-4 g/m 2 /yr characterize the westernmost region off Japan and the southern Kurile Islands south of 45 • N and west of 165 • E along the main pathway of the westerly winds. The core-top based dust flux reconstruction is consistent with recent estimates based on dissolved thorium isotope concentrations in seawater from the Subarctic North Pacific. The dust flux pattern compares well with state-of-the-art dust model predictions in the western and central Subarctic North Pacific, but we find that dust fluxes are higher than modeled fluxes by 0.5-1 g/m 2 /yr in the northwest, northeast and eastern Subarctic North Pacific. Our results provide an important benchmark for biogeochemical models and a robust approach for downcore studies testing dust-induced iron fertilization of past changes in biological productivity in the Subarctic North Pacific.

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Section: Spatial Dust Flux Pattern In the Subarctic North Pacificmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 95%

Section: Spatial Dust Flux Pattern In the Subarctic North Pacificmentioning

confidence: 99%

Section: Spatial Dust Flux Pattern In the Subarctic North Pacificmentioning

confidence: 99%

See 2 more Smart Citations

Eolian dust input to the Subarctic North Pacific

Serno

Winckler

Anderson

et al. 2014

Earth and Planetary Science Letters

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“…This approach, originally proposed by Hirose & Sugimura [58], has been applied in the Atlantic and Pacific Oceans [59][60][61][62]. This approach presents a particularity in that the calculated value of dust deposition generally increases with the depth below the sea surface to which dissolved 232 Th inventory and 230 Th residence time are integrated, levelling off below approximately 500 m [60,61].…”

Section: (A) Aerosol Depositionmentioning

confidence: 99%

How well can we quantify dust deposition to the ocean?

Anderson

Cheng

Edwards

et al. 2016

Phil. Trans. R. Soc. A.

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One contribution of 20 to a discussion meeting issue 'Biological and climatic impacts of ocean trace element chemistry'. Deposition of continental mineral aerosols (dust) in the Eastern Tropical North Atlantic Ocean, between the coast of Africa and the Mid-Atlantic Ridge, was estimated using several strategies based on the measurement of aerosols, trace metals dissolved in seawater, particulate material filtered from the water column, particles collected by sediment traps and sediments. Most of the data used in this synthesis involve samples collected during US GEOTRACES expeditions in 2010 and 2011, although some results from the literature are also used. Dust deposition generated by a global model serves as a reference against which the results from each observational strategy are compared. Observation-based dust fluxes disagree with one another by as much as two orders of magnitude, although most of the methods produce results that are consistent with the reference model to within a factor of 5. The large range of estimates indicates that further work is needed to reduce uncertainties associated with each method before it can be applied routinely to map dust deposition to the ocean. Calculated dust deposition using observational strategies thought to have the smallest uncertainties is lower than the reference model by a factor of 2-5, suggesting that the model may overestimate dust deposition in our study area.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

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Dust deposition in the eastern Indian Ocean: The ocean perspective from Antarctica to the Bay of Bengal

Grand

Measures

Hatta

et al. 2015

Global Biogeochemical Cycles

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Atmospheric deposition is an important but still poorly constrained source of trace micronutrients to the open ocean because of the dearth of in situ measurements of total deposition (i.e., wet + dry deposition) in remote regions. In this work, we discuss the upper ocean distribution of dissolved Fe and Al in the eastern Indian Ocean along a 95°E meridional transect spanning the Antarctic margin to the Bay of Bengal. We use the mixed layer concentration of dissolved Al in conjunction with empirical data in a simple steady state model to produce 75 estimates of total dust deposition that we compare with historical observations and atmospheric model estimates. Except in the northern Bay of Bengal where the Ganges-Brahmaputra river plume contributes to the inventory of dissolved Al, the surface distribution of dissolved Al along 95°E is remarkably consistent with the large-scale gradients in mineral dust deposition and multiple-source regions impacting the eastern Indian Ocean. The lowest total dust deposition fluxes are calculated for the Southern Ocean (66 ± 60 mg m À2 yr À1 ) and the highest for the northern end of the south Indian subtropical gyre (up to 940 mg m À2 yr À1 at 18°S) and in the southern Bay of Bengal (2500 ± 570 mg m À2 yr À1 ). Our total deposition fluxes, which have an uncertainty on the order of a factor of 3.5, are comparable with the composite atmospheric model data of Mahowald et al. (2005), except in the south Indian subtropical gyre where models may underestimate total deposition. Using available measurements of the solubility of Fe in aerosols, we confirm that dust deposition is a minor source of dissolved Fe to the Southern Ocean and show that aeolian deposition of dissolved Fe in the southern Bay of Bengal may be comparable to that observed underneath the Saharan dust plume in the Atlantic Ocean.

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Quantifying lithogenic inputs to the North Pacific Ocean using the long-lived thorium isotopes

Cited by 51 publications

References 82 publications

Eolian dust input to the Subarctic North Pacific

Eolian dust input to the Subarctic North Pacific

How well can we quantify dust deposition to the ocean?

Dust deposition in the eastern Indian Ocean: The ocean perspective from Antarctica to the Bay of Bengal

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