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Iron, nutrient, and phytoplankton distributions in Oregon coastal waters

Citation

Chase, Z and van Geen, A and Kosro, PM and Marra, J and Wheeler, PA, Iron, nutrient, and phytoplankton distributions in Oregon coastal waters, Journal of Geophysical Research: Oceans, 107, (C10) pp. 38.1-37.17. ISSN 2169-9275 (2002) [Refereed Article]


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Copyright Statement

Copyright 2002 by the American Geophysical Union

DOI: doi:10.1029/2001JC000987

Abstract

The relationship between iron and nitrate concentrations was examined off the coast of Oregon during the upwelling season. Surface Fe and N (nitrate + nitrite) concentrations measured underway by flow injection analysis ranged from <0.3 to 20 nmol L−1 and <0.1 to 30 μmol L−1, respectively. Total dissolvable Fe concentrations, measured in unfiltered, acidified samples in surface waters and in vertical profiles, ranged from <0.3 to 300 nmol L−1. Surface water Fe and N concentrations were highly variable and uncoupled. Our observations indicate two dominant sources of Fe to Oregon coastal waters: Slope or shelf sediments and the Columbia River. Sedimentary iron, probably largely in the particulate form, appears to be added to surface waters through wind-induced vertical mixing during strong winds, through thickening of the bottom mixed layer during relaxation or downwelling favorable wind conditions, and through outcropping of shelf bottom waters during upwelling events. The existence of multiple iron sources and the generally high iron concentrations may explain why the distribution of phytoplankton, measured both remotely (by Sea-viewing Wide Field-of-view Sensor) and underway (by in vivo fluorescence), appeared to be driven primarily by physical dynamics and was not strongly linked to the distribution of iron. Nevertheless, at some offshore stations where underway Fe concentrations were <0.3 nmol L−1, underway measurements of the physiological state of phytoplankton by fast repetition rate fluorometry were consistent with mild iron stress, and cross-shelf nutrient distributions were consistent with iron regulation of the magnitude of phytoplankton blooms.

Item Details

Item Type:Refereed Article
Keywords:iron, Oregon, upwelling, nutrients, coastal, chlorophyll
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Chase, Z (Associate Professor Zanna Chase)
ID Code:101497
Year Published:2002
Web of Science® Times Cited:24
Deposited By:IMAS Research and Education Centre
Deposited On:2015-06-25
Last Modified:2015-08-20
Downloads:163 View Download Statistics

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