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Iron(II) variability in the northeast subarctic Pacific Ocean


Schallenberg, C and Davidson, AB and Simpson, KG and Miller, LA and Cullen, JT, Iron(II) variability in the northeast subarctic Pacific Ocean, Marine Chemistry, 177, (Part 1) pp. 33-44. ISSN 0304-4203 (2015) [Refereed Article]

Copyright Statement

© 2015 Elsevier

DOI: doi:10.1016/j.marchem.2015.04.004


Distributions of dissolved iron (< 0.2 μm, dFe) and its reduced form, Fe(II), were measured during 3 cruises along Line P, a transect from the continental slope to the high nitrate, low chlorophyll (HNLC) northeast subarctic Pacific Ocean. Concentrations of Fe(II) ranged from below the detection limit (4.3 pM or less) to 330 pM, and dFe concentrations were as high as 3.6 nM. Maximum concentrations for both Fe(II) and dFe occurred in waters over the continental slope, with Fe(II) consistently increasing towards the bottom, consistent with Fe(II) supply from benthic sources on the continental shelf and slope. Low oxygen concentrations (~ 10 μM) and pH (~ 7.5) in the North Pacific oxygen deficient zone (ODZ) likely serve to stabilize Fe(II) and may contribute to enhanced dFe release from shelf and slope sediments via reductive dissolution. Concentration gradients along isopycnal surfaces indicate that Fe(II) is transported several hundred kilometers from the continental slope at depth, and there is evidence that episodic events may advect shelf-derived Fe(II) similar distances near the surface. Comparison of transport times and Fe(II) half-lives suggests that it is unlikely for pre-formed Fe(II) to be transported these distances, but that sedimentary particles advected off the shelf and slope may constitute a continuous source of Fe(II) both at depth and near the surface. At the offshore stations, the Fe(II) time series reveals deep local maxima that are transient in time and space and are consistent with a sporadic Fe(II) source, such as remineralization of sinking particles.

Item Details

Item Type:Refereed Article
Keywords:iron, iron(II), oxygen depletion, continental margin, sediment, redox, HNLC, Line P, Ocean Station Papa, subarctic Pacific, GEOTRACES
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Measurement and assessment of marine water quality and condition
UTAS Author:Schallenberg, C (Dr Christina Schallenberg)
ID Code:108991
Year Published:2015
Web of Science® Times Cited:15
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2016-05-16
Last Modified:2017-11-01

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