Processes influencing dissolved iron distributions below the surface at the Atlantic Ocean - Celtic Sea shelf edge
Processes influencing dissolved iron distributions below the surface at the Atlantic Ocean - Celtic Sea shelf edge
Shelf break systems are highly dynamic environments. However little is known about the influence that benthic interactions and water mass mixing may have on vertical distributions of iron in these systems. Dissolved Fe (< 0.4 ?m) concentrations were measured in samples from nine vertical profiles across the upper slope (150–2950 m water depth) at the Atlantic Ocean–Celtic Sea shelf break. Dissolved iron concentrations varied between less than 0.2 and 5.4 nM, and the resulting detailed section showed evidence of a range of processes influencing the Fe distributions. The near sea floor data were interpreted in terms of release and removal processes. The concentrations of dissolved Fe present in near seabed waters were consistent with release of Fe from in situ remineralisation of particulate organic matter at two upper slope stations, and possibly release from pore water upon resuspension on shelf. Lateral transport of dissolved iron was evident from elevated Fe concentrations in an intermediate nepheloid layer and its advection along isopycnals. Surface waters at the shelf break also showed evidence of vertical mixing of deeper iron-rich waters. These waters contained macronutrients that sustained primary productivity in these otherwise nutrient-depleted surface waters. The data also suggest some degree of stabilisation of relatively high concentrations of iron, presumably through ligand association or as colloids. This study supports the view that lateral export of dissolved iron to the interior of the ocean from shelf and coastal zones and may have important implications for the global budget of oceanic iron.
Dissolved iron, Particulate organic matter oxidation, Transport processes, Intermediate nepheloid layers, Vertical mixing, Northeast Atlantic, Celtic Sea shelf edge
156-170
Nedelec, F.
60a34fde-bc21-4fed-968e-ca0f13435f7a
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Mowlem, M.
6f633ca2-298f-48ee-a025-ce52dd62124f
March 2007
Nedelec, F.
60a34fde-bc21-4fed-968e-ca0f13435f7a
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Mowlem, M.
6f633ca2-298f-48ee-a025-ce52dd62124f
Nedelec, F., Statham, P.J. and Mowlem, M.
(2007)
Processes influencing dissolved iron distributions below the surface at the Atlantic Ocean - Celtic Sea shelf edge.
Marine Chemistry, 104 (3-4), .
(doi:10.1016/j.marchem.2006.10.011).
Abstract
Shelf break systems are highly dynamic environments. However little is known about the influence that benthic interactions and water mass mixing may have on vertical distributions of iron in these systems. Dissolved Fe (< 0.4 ?m) concentrations were measured in samples from nine vertical profiles across the upper slope (150–2950 m water depth) at the Atlantic Ocean–Celtic Sea shelf break. Dissolved iron concentrations varied between less than 0.2 and 5.4 nM, and the resulting detailed section showed evidence of a range of processes influencing the Fe distributions. The near sea floor data were interpreted in terms of release and removal processes. The concentrations of dissolved Fe present in near seabed waters were consistent with release of Fe from in situ remineralisation of particulate organic matter at two upper slope stations, and possibly release from pore water upon resuspension on shelf. Lateral transport of dissolved iron was evident from elevated Fe concentrations in an intermediate nepheloid layer and its advection along isopycnals. Surface waters at the shelf break also showed evidence of vertical mixing of deeper iron-rich waters. These waters contained macronutrients that sustained primary productivity in these otherwise nutrient-depleted surface waters. The data also suggest some degree of stabilisation of relatively high concentrations of iron, presumably through ligand association or as colloids. This study supports the view that lateral export of dissolved iron to the interior of the ocean from shelf and coastal zones and may have important implications for the global budget of oceanic iron.
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Published date: March 2007
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Reprinted in: Marine Chemistry, 104(3-4), 2007, 156-170, for special issue: Dedicated to the memory of Professor Roland Wollast.
Keywords:
Dissolved iron, Particulate organic matter oxidation, Transport processes, Intermediate nepheloid layers, Vertical mixing, Northeast Atlantic, Celtic Sea shelf edge
Identifiers
Local EPrints ID: 42885
URI: http://eprints.soton.ac.uk/id/eprint/42885
ISSN: 0304-4203
PURE UUID: 60c51db8-19e6-48f5-a185-d5fe3e6bfc0f
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Date deposited: 13 Dec 2006
Last modified: 16 Mar 2024 03:08
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Author:
F. Nedelec
Author:
M. Mowlem
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