Iron and humic‐type fluorescent dissolved organic matter in the Chukchi Sea and Canada Basin of the western Arctic Ocean

Nakayama, Yuta; Fujita, Satoshi; Kuma, Kenshi; Shimada, Koji

doi:10.1029/2010jc006779

Cited by 51 publications

(77 citation statements)

References 105 publications

(177 reference statements)

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“…3g, 4a, b). The overestimation is likely due to the underestimation of iron removal, because aggregation removal is not considered in our model , and the underestimation can be attributed to the fact that riverine inputs of neither iron nor organic ligands are considered (Nakayama et al, 2011;Nishimura et al, 2012;Klunder et al, 2012). The simulated iron concentrations were modestly overestimated in the Kuroshio extension region; this bias is likely attributable to the misplaced Kuroshio Current in our model (Misumi et al, 2011).…”

Section: Overview Of the Simulated Physical And Biogeochemical Fieldsmentioning

confidence: 90%

“…Most iron in rivers is thought to flocculate and be precipitated in estuaries, because seawater cations neutralize the negatively charged iron-bearing colloids (Boyle et al, 1977). The release of riverine organic ligands may also contribute to the distribution of iron in shelf regions (Nakayama et al, 2011;Nishimura et al, 2012;Klunder et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

Misumi

Lindsay

Moore³

et al. 2014

Biogeosciences

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Abstract. We investigated the simulated iron budget in ocean surface waters in the 1990s and 2090s using the Community Earth System Model version 1 and the Representative Concentration Pathway 8.5 future CO 2 emission scenario. We assumed that exogenous iron inputs did not change during the whole simulation period; thus, iron budget changes were attributed solely to changes in ocean circulation and mixing in response to projected global warming, and the resulting impacts on marine biogeochemistry. The model simulated the major features of ocean circulation and dissolved iron distribution for the present climate. Detailed iron budget analysis revealed that roughly 70 % of the iron supplied to surface waters in high-nutrient, low-chlorophyll (HNLC) regions is contributed by ocean circulation and mixing processes, but the dominant supply mechanism differed by region: upwelling in the eastern equatorial Pacific and vertical mixing in the Southern Ocean. For the 2090s, our model projected an increased iron supply to HNLC waters, even though enhanced stratification was predicted to reduce iron entrainment from deeper waters. This unexpected result is attributed largely to changes in gyre-scale circulations that intensified the advective supply of iron to HNLC waters. The simulated primary and export production in the 2090s decreased globally by 6 and 13 %, respectively, whereas in the HNLC regions, they increased by 11 and 6 %, respectively.Roughly half of the elevated production could be attributed to the intensified iron supply. The projected ocean circulation and mixing changes are consistent with recent observations of responses to the warming climate and with other Coupled Model Intercomparison Project model projections. We conclude that future ocean circulation has the potential to increase iron supply to HNLC waters and will potentially buffer future reductions in ocean productivity.

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Section: Overview Of the Simulated Physical And Biogeochemical Fieldsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

Misumi

Lindsay

Moore³

et al. 2014

Biogeosciences

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“…[8] The acidified iron samples were adjusted to pH 3.2 with a quartz-distilled formic acid ultrapure-grade ammonium buffer solution in a class-100 clean-air room in a laboratory [Nakayama et al, 2011]. The iron concentrations in buffered 0.22-mm filtered samples were determined by an automated Fe analyser (Kimoto Electric) using chelating resin preconcentration and chemiluminescence detection [Obata et al, 1993].…”

Section: Methodsmentioning

confidence: 99%

Vertical turbulent iron flux sustains the Green Belt along the shelf break in the southeastern Bering Sea

Tanaka¹,

Yasuda²,

Kuma³

et al. 2012

Geophysical Research Letters

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[1] To evaluate the impact of vertical turbulent iron flux on the summertime biological productivity in the Bering Sea Green Belt (GB), we conducted the concurrent observations of dissolved iron (D-Fe) and turbulence in the Bering Sea for the first time. We show that the GB can be sustained by iron supply from iron-rich, subsurface thick layer distributed along the southeastern shelf break where the GB is located, via strong turbulent vertical mixing. The flux ratio of D-Fe and nitrate was within the range of the N/Fe uptake ratio by GB phytoplankton, suggesting this flux of nutrients can sustain GB productivity. We also analyzed historical hydrographic data and suggest the thick subsurface layer along the GB is formed by the mixing of relatively warm water with some iron from the Aleutian Passes and ironrich outer-shelf cold water in which the D-Fe derived from seafloor sediment is suspended due to strong vertical mixing. Citation: Tanaka, T., I. Yasuda, K. Kuma, and J. Nishioka

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“…Zooplankton grazing is known to be an important autochthonous source of colored and fluorescent organic matter, including marine humic substances (Ortega-Retuerta et al, 2009;Nakayama et al, 2011). In fact, Fe-binding HS-like compounds were released in the presence of salp FPs and we could calculate an HS-like potential flux from FPs of 2.5 and 0.24 mg HS-like m −2 d −1 for the field and laboratory work, respectively ( Table 4).…”

Section: Impact Of Salp Fps On Fe Organic Speciationmentioning

confidence: 99%

First Evaluation of the Role of Salp Fecal Pellets on Iron Biogeochemistry

et al. 2017

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Planktonic grazers such as salps may have a dominant role in iron (Fe) cycling in surface waters of the Southern Ocean (SO). Salps have high ingestion rates and egest large, fast sinking fecal pellets (FPs) that potentially contribute to the vertical flux of carbon. In this study, we determined the impact of FPs from Salpa thompsoni, the most abundant salp in the SO, on Fe biogeochemistry. During the Polarstern expedition ANT-XXVII/3, salps were sampled from a large diatom bloom area in the Atlantic sector of the SO. Extensive work on carbon export and salp FPs export at the sampling location had shown that salps were a minor component of zooplankton and were responsible for only a 0.2% consumption of the daily primary production. Furthermore, at 100 m, export efficiency of salp FPs was ∼2-3 fold higher than that of the bulk of sinking particulate organic carbon (POC). After collection, salps were maintained in 200 µm screened seawater and their FPs were collected for further experiments. To investigate whether the FPs release Fe and/or Fe-binding ligands into the filtered seawater (FSW) under different experimental conditions, they were either incubated in the dark or under full sunlight at in situ temperatures for 24 h, or placed into the dark after a freeze/thaw treatment. We observed that none of the treatments caused release of dissolved Fe (dFe) or strong Fe ligands from the salp FPs. However, humic-substance like (HS-like) compounds, weak Fe ligands, were released at a rate of 8.2 ± 4.7 µg HS-like FP −1 d −1 . Although the Fe content per salp FP was high at 0.33 −1 ± 0.02 nmol dFe FP , the small contribution of salps to the zooplankton pool resulted in an estimated dFe export flux of 11.3 nmol Fe m −2 d −1 at 300 m. Since salp FPs showed an export efficiency at 100 m well above that shown by the bulk of sinking POC, our results suggest that in those areas of the SO where salps play a major role in the grazing of primary production, they could be actively contributing to the depletion of the dFe pool in surface water.

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Iron and humic‐type fluorescent dissolved organic matter in the Chukchi Sea and Canada Basin of the western Arctic Ocean

Cited by 51 publications

References 105 publications

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

Vertical turbulent iron flux sustains the Green Belt along the shelf break in the southeastern Bering Sea

First Evaluation of the Role of Salp Fecal Pellets on Iron Biogeochemistry

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