Deep dissolved iron profiles in the eastern North Atlantic in relation to water masses

Laës-Huon, Agathe; Blain, Stéphane; Laan, Patrick; Achterberg, Eric P.; Sarthou, Géraldine; Baar, H. J. W. de

doi:10.1029/2003gl017902

Cited by 46 publications

(31 citation statements)

References 21 publications

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“…It could also be caused by low intensity and short term advective transport at this period of the study. This confirms that the long distance transport of DFe away from its source is only possible when specific conditions are met, such as strong advection and low scavenging as reported by Laës et al (2003).…”

Section: Distributions Of Dfe and Dmnsupporting

confidence: 70%

Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay

Laës-Huon¹,

Blain

Laan

et al. 2007

Biogeosciences

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Abstract. Dissolved iron (DFe; <0.2 µm) and dissolved manganese (DMn; <0.2 µm) concentrations were determined in the water column of the Bay of Biscay (eastern North Atlantic Ocean) in March 2002. The samples were collected along a transect traversing from the European continental shelf over the continental slope. The highest DFe and DMn concentrations (2.39 nM and 6.10 nM, respectively) were observed in the bottom waters on the shelf at stations closest to the coast. The release of trace metal from resuspended particles and the diffusion from pore waters were probably at the origin of elevated DFe and DMn concentrations in the Bottom Boundary Layer (BBL). In the slope region, the highest total dissolvable iron (TDFe), DFe and DMn values (24.6 nM, 1.58 nM and 2.12 nM, respectively) were observed close to the bottom at depth of ca. 600-700 m. Internal wave activity and slope circulation are thought to be at the origin of this phenomenon. These processes were also very likely the cause of elevated concentrations (DFe: 1.27 nM, DMn: 2.34 nM) measured in surface waters of stations located in the same area. At stations off the continental slope, the vertical distribution of both metals were typical of open ocean conditions, indicating that inputs from the continental margin did not impact the metal distributions in the offshore waters.

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Section: Distributions Of Dfe and Dmnsupporting

confidence: 70%

Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay

Laës-Huon¹,

Blain

Laan

et al. 2007

Biogeosciences

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“…The minimum of salinity and potential temperature at 550 m depth separated the MOW and the NACW (van Aken 2001). At about 2000 m depth the NADW proper was found and below 4000 m low deep water was recognised, with Antarctic bottom water (AABW) influence (for more details, see Measures et al, 1995;Laës et al, 2003).…”

Section: Resultsmentioning

confidence: 99%

Speciation of Fe in the Eastern North Atlantic Ocean

Thuroczy

Gerringa

Klunder

et al. 2010

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tIn the Eastern North Atlantic Ocean iron (Fe) speciation was investigated in three size fractions: the dissolvable from unfiltered samples, the dissolved fraction (o 0.2 mm) and the fraction smaller than 1000 kDa ( o 1000 kDa). Fe concentrations were measured by flow injection analysis and the organic Fe complexation by voltammetry. In the research area the water column consisted of North Atlantic Central Water (NACW), below which Mediterranean Overflow Water (MOW) was found with the core between 800 and 1000 m depth. Below 2000 m depth the North Atlantic Deep Water (NADW) proper was recognised. Dissolved Fe and Fe in the o 1000 kDa fraction showed a nutrient like profile, depleted at the surface, increasing until 500-1000 m depth below which the concentration remained constant. Fe in unfiltered samples clearly showed the MOW with high concentrations (4 nM) compared to the overlying NACW and the underlying NADW, with 0.9 nM and 2 nM Fe, respectively. By using excess ligand (Excess L) concentrations as parameter we show a potential to bind Fe. The surface mixed layer had the highest excess ligand concentrations in all size fractions due to phytoplankton uptake and possible ligand production. The ratio of Excess L over Fe proved to be a complementary tool in revealing the relative saturation state of the ligands with Fe. In the whole water column, the organic ligands in the larger colloidal fraction (between 0.2 mm and 1000 kDa) were saturated with Fe, whereas those in the smallest fraction ( o1000 kDa) were not saturated with Fe, confirming that this fraction was the most reactive one and regulates dissolution and colloid aggregation and scavenging processes. This regulation was remarkably stable with depth since the alpha factor (product of Excess L and K 0 ), expressing the reactivity of the ligands, did not vary and was 10 13 . Whereas, in the NACW and the MOW, the ligands in the particulate (4 0.2 mm) fraction were unsaturated with Fe with respect to the dissolved fraction, thus these waters had a scavenging potential.Crown

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“…DFe concentrations were measured on shore in a clean room using flow-injection analysis with chemiluminescence detection. The mean detection limit was 20 pmol L Ϫ1 and the mean blank was 30 pmol L Ϫ1 (Laes et al 2003). In situ concentrations of NO and NO were analyzed…”

Section: Methodsmentioning

confidence: 99%

Availability of iron and major nutrients for phytoplankton in the northeast Atlantic Ocean

Blain

Guieu

Claustre

et al. 2004

Limnology & Oceanography

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Because of recent findings that Fe is a limiting factor for phytoplankton activity even at relatively high dissolved iron (DFe) concentrations, the potential importance of Fe limitation was revisited in the northeast Atlantic Ocean (39-45ЊN, 17-21ЊW). We report data gathered during deck incubation experiments performed at three stations in February-March 2001 with surface seawater containing DFe concentrations of ϳ0.40 nmol L Ϫ1 . At all stations, Fe addition enhanced phytoplankton growth. Fe limitation was moderate and occurred simultaneously with limitation by major nutrients. This was clearly demonstrated for diatoms that were colimited by orthosilicic acid. Micro-, nano-, and picoplankton benefited from Fe enrichment. Experiments performed with the trihydroxamate siderophore desferrioxamine mesylate B (DFOB) indicated that Fe reserves exist within the cells, especially within the larger cells. This reserve could result from luxurious storage of Fe by colimited cells during episodic atmospheric deposition of Saharan dust. Simulating concentrations of dust resulting from aerosol deposition in well-stratified surface waters, we determined that the solubility of Saharan dust was very low (Ͻ0.1% w/w) but the amount of DFe released in seawater was sufficient to relieve the Fe limitation of the ambient phytoplankton community.

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Deep dissolved iron profiles in the eastern North Atlantic in relation to water masses

Cited by 46 publications

References 21 publications

Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay

Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay

Speciation of Fe in the Eastern North Atlantic Ocean

Availability of iron and major nutrients for phytoplankton in the northeast Atlantic Ocean

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