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Leachable particulate iron in the Columbia River, estuary, and near-field plume

Leachable particulate iron in the Columbia River, estuary, and near-field plume
Leachable particulate iron in the Columbia River, estuary, and near-field plume

This study examines the distribution of leachable particulate iron (Fe) in the Columbia River, estuary, and near-field plume. Surface samples were collected during late spring and summer of 2004-2006 as part of four River Influence on Shelf Ecosystems (RISE) cruises. Tidal amplitude and river flow are the primary factors influencing the estuary leachable particulate Fe concentrations, with greater values during high flow and/or spring tides. Near the mouth of the estuary, leachable particulate Fe [defined as the particulate Fe solubilized with a 25% acetic acid (pH 2) leach containing a weak reducing agent to reduce Fe oxyhydroxides and a short heating step to access intracellular Fe] averaged 770 nM during either spring tide or high flow, compared to 320 nM during neap tide, low flow conditions. In the near-field Columbia River plume, elevated leachable particulate Fe concentrations occur during spring tides and/or higher river flow, with resuspended shelf sediment as an additional source to the plume during periods of coastal upwelling and spring tides. Near-field plume concentrations of leachable particulate Fe (at a salinity of 20) averaged 660 nM during either spring tide or high flow, compared to 300 nM during neap tide, low flow conditions. Regardless of tidal amplitude and river flow, leachable particulate Fe concentrations in both the river/estuary and near-field plume are consistently one to two orders of magnitude greater than dissolved Fe concentrations. The Columbia River is an important source of reactive Fe to the productive coastal waters off Oregon and Washington, and leachable particulate Fe is available for solubilization following biological drawdown of the dissolved phase. Elevated leachable Fe concentrations allow coastal waters influenced by the Columbia River plume to remain Fe-replete and support phytoplankton production during the spring and summer seasons.

Columbia river, iron, river plumes, suspended particulate matter, USA, Washington/Oregon
0272-7714
33-42
Lippiatt, Sherry M.
88a7b0f6-f120-4a54-86fe-ce0fe9081b93
Brown, Matthew T.
dc9b92df-a3e0-47ee-abff-1c0fff827ce3
Lohan, Maeve C.
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Berger, Carolyn J M
6ed7401f-be10-40b8-a31f-70c6f8046228
Bruland, Kenneth W.
f3e947c6-f9b7-435c-ac84-b3476306a368
Lippiatt, Sherry M.
88a7b0f6-f120-4a54-86fe-ce0fe9081b93
Brown, Matthew T.
dc9b92df-a3e0-47ee-abff-1c0fff827ce3
Lohan, Maeve C.
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Berger, Carolyn J M
6ed7401f-be10-40b8-a31f-70c6f8046228
Bruland, Kenneth W.
f3e947c6-f9b7-435c-ac84-b3476306a368

Lippiatt, Sherry M., Brown, Matthew T., Lohan, Maeve C., Berger, Carolyn J M and Bruland, Kenneth W. (2010) Leachable particulate iron in the Columbia River, estuary, and near-field plume. Estuarine, Coastal and Shelf Science, 87 (1), 33-42. (doi:10.1016/j.ecss.2009.12.009).

Record type: Article

Abstract

This study examines the distribution of leachable particulate iron (Fe) in the Columbia River, estuary, and near-field plume. Surface samples were collected during late spring and summer of 2004-2006 as part of four River Influence on Shelf Ecosystems (RISE) cruises. Tidal amplitude and river flow are the primary factors influencing the estuary leachable particulate Fe concentrations, with greater values during high flow and/or spring tides. Near the mouth of the estuary, leachable particulate Fe [defined as the particulate Fe solubilized with a 25% acetic acid (pH 2) leach containing a weak reducing agent to reduce Fe oxyhydroxides and a short heating step to access intracellular Fe] averaged 770 nM during either spring tide or high flow, compared to 320 nM during neap tide, low flow conditions. In the near-field Columbia River plume, elevated leachable particulate Fe concentrations occur during spring tides and/or higher river flow, with resuspended shelf sediment as an additional source to the plume during periods of coastal upwelling and spring tides. Near-field plume concentrations of leachable particulate Fe (at a salinity of 20) averaged 660 nM during either spring tide or high flow, compared to 300 nM during neap tide, low flow conditions. Regardless of tidal amplitude and river flow, leachable particulate Fe concentrations in both the river/estuary and near-field plume are consistently one to two orders of magnitude greater than dissolved Fe concentrations. The Columbia River is an important source of reactive Fe to the productive coastal waters off Oregon and Washington, and leachable particulate Fe is available for solubilization following biological drawdown of the dissolved phase. Elevated leachable Fe concentrations allow coastal waters influenced by the Columbia River plume to remain Fe-replete and support phytoplankton production during the spring and summer seasons.

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More information

Published date: 20 March 2010
Keywords: Columbia river, iron, river plumes, suspended particulate matter, USA, Washington/Oregon
Organisations: Marine Biogeochemistry, Southampton Marine & Maritime Institute

Identifiers

Local EPrints ID: 411657
URI: http://eprints.soton.ac.uk/id/eprint/411657
ISSN: 0272-7714
PURE UUID: aaebb081-77cc-425c-960c-6a39fda73b3b
ORCID for Maeve C. Lohan: ORCID iD orcid.org/0000-0002-5340-3108

Catalogue record

Date deposited: 21 Jun 2017 16:33
Last modified: 07 Oct 2020 02:02

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