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Marine Chemistry 01/2012; 132-133:28-33. · 3.07 Impact Factor
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Breitbarth E,
E. P. Achterberg, M. V. Ardelan,
A. R. Baker,
Bucciarelli E,
Chever F,
P. L. Croot,
Duggen S,
Gledhill M,
Hassellöv M, [......],
D. A. Hutchins,
Ingri J,
Jickells T,
M. C. Lohan,
M. C. Nielsdóttir,
Sarthou G,
Schoemann V,
J. M. Trapp,
D. R. Turner,
Ye Y
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ABSTRACT: Based on an international workshop (Gothenburg, 14–16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas.
Biogeosciences 01/2010; 7(3):1075-1097. · 3.86 Impact Factor
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ABSTRACT: Rising atmospheric CO2 is acidifying the surface ocean, a process which is expected to greatly influence the chemistry and biology of the future ocean. Following the development of iron-replete phytoplankton blooms in a coastal mesocosm experiment at 350, 700, and 1050 μatm pCO2, we observed significant increases in dissolved iron concentrations, Fe(II) concentrations, and Fe(II) half-life times during and after the peak of blooms in response to CO2 enrichment and concomitant lowering of pH, suggesting increased iron bioavailability. If applicable to the open ocean this may provide a negative feedback mechanism to the rising atmospheric CO2 by stimulating marine primary production.
Biogeosciences 01/2010; · 3.86 Impact Factor
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Breitbarth E,
E. P. Achterberg, M. V. Ardelan,
A. R. Baker,
Bucciarelli E,
Chever F,
P. L. Croot,
Duggen S,
Gledhill M,
Hassellöv M, [......],
D. A. Hutchins,
Ingri J,
Jickells T,
M. C. Lohan,
M. C. Nielsdóttir,
Sarthou G,
Schoemann V,
J. M. Trapp,
D. R. Turner,
Ye Y
[show abstract]
[hide abstract]
ABSTRACT: Based on an international workshop (Gothenburg, 14–16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas.
Biogeosciences 01/2010; · 3.86 Impact Factor
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ABSTRACT: The impact of CO<sub>2</sub> seepage on the solubility and distribution of the redox-sensitive metals iron, manganese, and cobalt in seawater and sediment pore water has been studied in experiments in laboratory-scale 0.6 m<sup>3</sup> chambers. The mobility and solubility of Fe, Mn and Co were investigated in seawater, membrane filtered seawater, and DGT samplers deployed in water and sediment during a 26 day CO<sub>2</sub> seepage study.
During the first phase of the experiment of CO<sub>2</sub> seepage (0–16 days), total acid-leachable (pH≈1) and "dissolved" (<0.2 μm) concentrations of Fe, Mn and Co (DFe, DMn and DCo) in the seawater increased significantly; the ratios of concentrations of DFe, DMn and DCo in the CO<sub>2</sub> chamber to the corresponding values in the control chamber ( R <sub>DFe</sub>, R <sub>DMn</sub> and R <sub>DCo</sub>) were as high as 6, 65 and 58, respectively. The second phase of experiment consisted of an additional 10 days of incubation, where the concentrations of all the metals studied still increased but at reduced rates for DMn and DCo. The highest values of R <sub>DFe</sub>, R <sub>DMn</sub> and R <sub>DCo</sub> were about 3 for all metals during this part of the experiment.
DGT (diffusive gradients in thin film) labile fractions denoted Fe<sub>DGT</sub>, Mn<sub>DGT</sub> and Co<sub>DGT</sub> were, respectively 50, 25 and 22 times higher in the CO<sub>2</sub> seepage chamber than in the control chamber in the first phase of the experiment. During the second phase, all DGT labile metal concentrations still increased considerably, most notably for Fe. The ratio of Fe<sub>DGT</sub> in the CO<sub>2</sub> chamber to that in the control ( R <sub>DGT-Fe</sub>) was still high, about 5, in the second phase of the experiment, whereas the increase in Mn<sub>DGT</sub> and Co<sub>DGT</sub> slowed down.
Our results indicate that acidification following CO<sub>2</sub> seepage enhances the mobility and solubility of Fe Mn and Co in sediment and overlying water with contribution of changing in redox conditions and seepage related re-suspension.
Biogeosciences Discussions. 01/2009;
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ABSTRACT: As part of the US-AMLR program that occupied 99 hydrographic stations in the South Shetland Islands-Antarctic Peninsula region in January–February of 2006, concentrations of dissolved iron (DFe) and total acid-leachable iron (TaLFe) were measured in the upper 150 m at 16 stations (both coastal and pelagic waters). The concentrations in the upper mixed layer (UML) of DFe and TaLFe were relatively high in Weddell Sea Shelf Waters (~0.6 nM and 15 nM, respectively) and lowest in Drake Passage waters (~0.2 nM and 0.9 nM, respectively). In the Bransfield Strait, representing a mixture of waters from the Weddell Sea and the Antarctic Circumpolar Current (ACC), concentrations of DFe were ~0.4 nM and of TaLFe ~1.7 nM. The highest concentrations of DFe and TaLFe in the UML were found at shallow coastal stations close to Livingston Island (~1.6 nM and 100 nM, respectively). The ratio of TaLFe:DFe varied with the distance to land: ~45 at the shallow coastal stations, ~15 in the high-salinity waters of Bransfield Strait, and ~4 in ACC waters. Concentrations of DFe increased slightly with depth in the water column, while that of TaLFe did not show any consistent trend with depth. Our data are consistent with the hypothesis that the relatively high rates of primary production known from the central regions of the Scotia Sea are partially sustained by natural iron enrichment resulting from a northeasterly flow of iron-rich coastal waters originating in the South Shetland Islands-Antarctic Peninsula region.
Biogeosciences Discussions. 01/2009;
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ABSTRACT: In the Southern Ocean near the Antarctic Peninsula, Antarctic Circumpolar Current (ACC) fronts interact with shelf waters facilitating lateral transport of shelf-derived components such as iron into high-nutrient offshore regions. To trace these shelf-derived components and estimate lateral mixing rates of shelf water, we used naturally occurring radium isotopes. Short-lived radium isotopes were used to quantify the rates of shelf water entrainment while Fe/228Ra ratios were used to calculate the Fe flux. In the summer of 2006 we found rapid mixing and significant lateral iron export, namely, a dissolved iron flux of 1.1 × 105 mol d−1 and total acid leachable iron flux of 1.1 × 106 mol d−1 all of which is transported in the mixed layer from the shelf region offshore. This dissolved iron flux is significant, especially considering that the bloom observed in the offshore region (0.5–2 mg chl a m−3) had an iron demand of 1.1 to 4 × 105 mol Fe. Net vertical export fluxes of particulate Fe derived from 234Th/238U disequilibrium and Fe/234Th ratios accounted for only about 25% of the dissolved iron flux. On the other hand, vertical upward mixing of iron rich deeper waters provided only 7% of the lateral dissolved iron flux. We found that similarly to other studies in iron-fertilized regions of the Southern Ocean, lateral fluxes overwhelm vertical inputs and vertical export from the water column and support significant phytoplankton blooms in the offshore regions of the Drake Passage. Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 23 (2009): GB4014, doi:10.1029/2008GB003406. This work was funded by the National Science Foundation (ANT-0443869 to M.A.C.).
