Iron biogeochemistry across marine systems – progress from the past decade

Breitbarth, Eike; Achterberg, Eric P.; Ardelan, Murat Van; Baker, Alex R.; Bucciarelli, Eva; Chever, Fanny; Croot, Peter; Duggen, Svend; Gledhill, Martha; Hassellöv, Martin; Hassler, Christel; Hoffmann, Linn; Hunter, Keith A.; Hutchins, David A.; Ingri, Johan; Jickells, Tim; Lohan, Maeve C.; Nielsdóttir, Maria C.; Sarthou, Géraldine; Schoemann, Véronique; Trapp, J. M.; Turner, David R.; Ye, Ying

doi:10.5194/bg-7-1075-2010

Cited by 80 publications

(65 citation statements)

References 272 publications

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“…Considerations on Fe measurements-Before discussing our results, it is important to keep in mind that both TDFe and DFe are operational definitions of Fe concentrations in the water and do not represent bioavailable Fe, a form notoriously difficult to quantify (Breitbarth et al 2010). DFe (, 0.22 mm) encompasses soluble and colloidal forms of Fe, both of which could be directly available to plankton (Morel et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Early response of the northeast subarctic Pacific plankton assemblage to volcanic ash fertilization

Melancon

Levasseur

Lizotte

et al. 2014

Limnology & Oceanography

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Fe-poor water collected at Sta. P20 in the Gulf of Alaska in June 2011 was enriched with different concentrations of volcanic ash (0.12, 1.2, and 10 mg L 21 ) from two subduction zone volcanoes, Kasatochi and Chaiten, and incubated onboard under in situ conditions for 6 d. The experimental setup also included a control (no addition) and a positive control (addition of 0.6 nmol L 21 FeSO 4 ). Following a 4 d lag period, there were increases in carbon fixation rates (up to a factor of 10) and chlorophyll a concentrations (up to a factor of 3) in the positive control and in the ash-enriched (1.2 and 10 mg L 21 ) treatments. Diatoms dominated at the end of the incubations, but cyanobacteria, dinoflagellates, pelagophytes, and haptophytes were also stimulated by the presence of ash. Deposition of , 1 mg ash L 21 , which is in the lower range of those estimated to have caused the August 2008 bloom following the eruption of the Kasatochi volcano in the Aleutian Islands, would suffice to trigger a bloom in the Gulf of Alaska.

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Section: Discussionmentioning

confidence: 99%

Early response of the northeast subarctic Pacific plankton assemblage to volcanic ash fertilization

Melancon

Levasseur

Lizotte

et al. 2014

Limnology & Oceanography

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“…5). Although a decrease in pH would favor the solubility of DFe (Breitbarth et al, 2010a), DFe concentrations did not increase with increasing pCO 2 (Fig. 5).…”

Section: Nutrient Dynamics: Biological Vs Acidification Effectmentioning

confidence: 99%

Nutrient dynamics under different ocean acidification scenarios in a low nutrient low chlorophyll system: The Northwestern Mediterranean Sea

Louis¹,

Guieu²,

Gazeau³

2017

Estuarine, Coastal and Shelf Science

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Highlights:-Mesocosm experiments performed in two Mediterranean sites during two seasons -Contrasted nutrient stoichiometry in surface waters in summer and winter -Dissolved organic pool was a large stable fraction of N and P in summer and winter -CO 2 had no effect on nutrient dynamics that was mostly biologically controlled Keywords: ocean acidification; plankton community; mesocosm experiments; nutrient dynamics; nitrogen; phosphorus; iron; stoichiometry; Oligotrophy; Mediterranean Sea M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 2 AbstractTwo pelagic mesocosm experiments were conducted to study the impact of ocean acidification on Mediterranean plankton communities. A first experiment took place in summer 2012 in the Bay of Calvi (France) followed by an experiment in winter 2013 in the Bay of Villefranche (France) under pre-bloom conditions. Nine mesocosms were deployed: three served as controls and six were acidified in a targeted partial pressure of CO 2 (pCO 2 ) gradient from 450 to 1250 µatm. The evolution of dissolved organic and inorganic nutrient concentrations was observed using nanomolar techniques. The experiments were characterized by a large contribution of organic nutrients to nutrient pools and contrasting in situ conditions with an inorganic N / P ratio of 1.7 in summer and of 117 in winter. In the Bay of Calvi, initial conditions were representative of the summer oligotrophic Mediterranean Sea.While inorganic phosphate concentrations were depleted during both experiments, in situ inorganic nitrogen concentrations were higher in winter. However, nitrate was rapidly consumed in winter in all mesocosms during the acidification phase, leading to a decrease in N / P ratio to 13. During these first mesocosm experiments conducted in a low nutrient low chlorophyll area, nutrient dynamics were insensitive to CO 2 enrichment, indicating that nutrient speciation and related biological processes were likely not impacted. During both experiments, nitrate and phosphate dynamics were controlled by the activity of small species that are favored in low nutrient conditions. In contrast to the theoretical knowledge, no increase in iron solubility at high pCO 2 was observed. M A N U S C R I P T A C C E P T E DACCEPTED MANUSCRIPT 3 IntroductionSince the beginning of the industrial era, the atmospheric carbon dioxide (CO 2 ) level has increased by nearly 40% (from ~280 to 390 ppm in 2011; Hartmann et al., 2013) and may reach between ~450 and ~1000 ppm by 2100 depending on the considered future emission scenario (Collins et al., 2013). As the ocean absorbs about a quarter of total anthropogenic CO 2 emissions (Le Quéré et al., 2014), the increase in CO 2 dissolved in seawater leads to an increase in seawater acidity (decrease in pH). Surface ocean pH has already declined by approximately 0.1 since the beginning of the industrial era (Orr, 2005) and is expected to decrease an additional 0.06 to 0.32 by the end of this century depending on the considered ) and an alteration of the NH 4 + / NH 3 equilibriu...

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“…An increase in anthropogenic carbon reduces ocean pH (Caldeira and Wickett, 2003;Orr et al, 2005;Doney et al, 2009c;Doney 2010), and ocean acidification changes iron speciation, but it is not known whether it increases or decreases bioavailable iron. A reduction in pH increases the thermodynamic solubility of Fe(III) near a pH of 8 (Kuma et al, 1996;Liu and Millero, 2002) and slows the oxidation rate of Fe(II) (Millero et al, 1987;Breitbarth et al, 2010). A four times atmospheric CO 2 experiment considering effects of dissolved oxygen, temperature, light and pH on iron speciation demonstrated that decrease in pH increases the fraction of Fe(II) and the pH effect overrides the others (Tagliabue and Völker, 2011).…”

Section: Other Factors Changing the Iron Cycle In The Future Oceanmentioning

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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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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Iron biogeochemistry across marine systems – progress from the past decade

Cited by 80 publications

References 272 publications

Early response of the northeast subarctic Pacific plankton assemblage to volcanic ash fertilization

Early response of the northeast subarctic Pacific plankton assemblage to volcanic ash fertilization

Nutrient dynamics under different ocean acidification scenarios in a low nutrient low chlorophyll system: The Northwestern Mediterranean Sea

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

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