Observation of consistent trends in the organic complexation of dissolved iron in the Atlantic sector of the Southern Ocean

Thuróczy, Charles-Edouard; Gerringa, Loes J. A.; Klunder, Maarten B; Laan, Patrick; Baar, H. J. W. de

doi:10.1016/j.dsr2.2011.01.002

Cited by 63 publications

(72 citation statements)

References 57 publications

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“…Note that data points below 2 km were removed by our shelf adjustment/definition. At the other extreme, the off-shelf data show a much clearer nutrient/scavenged element profile, with a surface water minimum of 0.31 ± 0.45 (n = 999) that increases with depth to 0.54 ± 0.26 nM (n = 301), which is less than the reported concentration of Fe-binding ligands in Southern Ocean deep waters (e.g., ∼0.6-1.8 nM, Croot et al, 2004;Boye et al, 2010;Ibisamni et al, 2011;Thuroczy et al, 2011), although there are very few ligand data below 1000 m. From within Table 1. A summary of the dFe sampling frequency, number of months sampled, number of observations (N ) and mean concentration (± the standard deviation) for each depth range and Southern Ocean region.…”

Section: Dfe Distributions Between Regions and Basinsmentioning

confidence: 50%

“…2b, Table 2). Interestingly, Thuroczy et al (2011) found ligand concentrations >1nM in the intermediate waters of their ATL Subantarctic stations, which corresponds well with the increased intermediate depth dFe (Fig. 2b, Table 2).…”

Section: Dfe Distribution and Processesmentioning

confidence: 50%

“…1a, Table 1). In the Subantarctic region, the higher deep water values of Thuroczy et al (2011) from the ATL (∼1 nM) and the deepest samples at 1000 m by Ibisanmi et al (2011) in the IND basin (0.58-0.83 nM) suggest that the increasing dFe (>2000 m depth) trend between the ATL-Subantarctic and the IND-Subantarctic is not reflected by a similar increasing trend in ligand concentrations (although we draw attention to the different detection windows used in each study). This may mean that inter-basin differences between the ATL and IND reflect different Fe inputs.…”

Section: Dfe Distribution and Processesmentioning

confidence: 99%

“…Thuroczy et al (2011) report measurements from both the Subantarctic and Antarctic regions of the ATL basin. At depths of ∼4 km, ligand concentrations were ∼1 nM in the Subantarctic ATL, while the Antarctic ATL concentrations were only ∼0.7 nM (Thuroczy et al, 2011), which matches well with our higher deep dFe in the ATL-Subantarctic as compared to the ATL-Antarctic (Fig. 2b, Table 2).…”

Section: Dfe Distribution and Processesmentioning

confidence: 99%

“…There are of course not as many measurements of Fe ligands as for dFe, and subtle methodological issues (e.g., different detection windows) can complicate intermethod comparisons (e.g., Hudson et al, 2003). Thuroczy et al (2011) report measurements from both the Subantarctic and Antarctic regions of the ATL basin. At depths of ∼4 km, ligand concentrations were ∼1 nM in the Subantarctic ATL, while the Antarctic ATL concentrations were only ∼0.7 nM (Thuroczy et al, 2011), which matches well with our higher deep dFe in the ATL-Subantarctic as compared to the ATL-Antarctic (Fig.…”

Section: Dfe Distribution and Processesmentioning

confidence: 99%

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A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

et al. 2012

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Abstract. Due to its importance as a limiting nutrient for phytoplankton growth in large regions of the world's oceans, ocean water column observations of concentration of the trace-metal iron (Fe) have increased markedly over recent decades. Here we compile >13 000 global measurements of dissolved Fe (dFe) and make this available to the community. We then conduct a synthesis study focussed on the Southern Ocean, where dFe plays a fundamental role in governing the carbon cycle, using four regions, six basins and five depth intervals as a framework. Our analysis highlights depth-dependent trends in the properties of dFe between different regions and basins. In general, surface dFe is highest in the Atlantic basin and the Antarctic region. While attributing drivers to these patterns is uncertain, inter-basin patterns in surface dFe might be linked to differing degrees of dFe inputs, while variability in biological consumption between regions covaries with the associated surface dFe differences. Opposite to the surface, dFe concentrations at depth are typically higher in the Indian basin and the Subantarctic region. The inter-region trends can be reconciled with similar ligand variability (although only from one cruise), and the inter-basin difference might be explained by differences in hydrothermal inputs suggested by modelling studies ) that await observational confirmation. We find that even in regions where many dFe measurements exist, the processes governing the seasonal evolution of dFe remain enigmatic, suggesting that, aside from broad Subantarctic -Antarctic trends, biological consumption might not be the major driver of dFe variability. This highlights the apparent importance of other processes such as exogenous inputs, physical transport/mixing or dFe recycling processes. Nevertheless, missing measurements during key seasonal transitions make it difficult to better quantify and understand surface water replenishment processes and the seasonal Fe cycle. Finally, we detail the degree of seasonal coverage by region, basin and depth. By synthesising prior measurements, we suggest a role for different processes and highlight key gaps in understanding, which we hope can help structure future research efforts in the Southern Ocean.

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Section: Dfe Distributions Between Regions and Basinsmentioning

confidence: 50%

Section: Dfe Distribution and Processesmentioning

confidence: 50%

Section: Dfe Distribution and Processesmentioning

confidence: 99%

Section: Dfe Distribution and Processesmentioning

confidence: 99%

Section: Dfe Distribution and Processesmentioning

confidence: 99%

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A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

et al. 2012

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A ventilation‐based framework to explain the regeneration‐scavenging balance of iron in the ocean

Tagliabue

Williams

Rogan

et al. 2014

Geophysical Research Letters

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Our understanding of the processes driving the patterns of dissolved iron (DFe) in the ocean interior, either in observations or models, is complicated by the combined influences of subduction from the surface mixed layer, notable subsurface sources, regeneration, and scavenging loss. We describe a ventilation-based framework to quantify these processes in a global ocean biogeochemical model including diagnostics along potential density surfaces. There is a prevailing control of subsurface DFe by the subduction of surface DFe as preformed DFe augmented by benthic sources of DFe from hydrothermal activity and sediments. Unlike phosphate, there is often a first-order balance with a near cancelation between regeneration and scavenging with the remaining "net regeneration" controlled by the ventilation of surface excesses in Fe-binding ligands. This DFe framework provides a more stringent test of how the total DFe distribution is mechanistically controlled within a model and may be subsequently used to interpret observed DFe distributions.

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2016

Iron Cycle in Oceans

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Observation of consistent trends in the organic complexation of dissolved iron in the Atlantic sector of the Southern Ocean

Cited by 63 publications

References 57 publications

A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

A ventilation‐based framework to explain the regeneration‐scavenging balance of iron in the ocean

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