Retention of dissolved iron and Fe II in an iron induced Southern Ocean phytoplankton bloom

During the 13 day Southern Ocean Iron RElease Experiment (SOIREE), dissolved iron concentrations decreased rapidly following each of three iron-enrichments, but remained high (> 1 nM, up to 80% as FeII) after the fourth and final enrichment on day 8. The former trend was mainly due to dilution (s...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Croot, PL, Bowie, AR, Frew, RD, Maldonado, MT, Hall, JA, Safi, KL, Roche, JL, Boyd, PW, Law, CS
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union 2001
Subjects:
Earth Sciences
Oceanography
Chemical Oceanography
Southern Ocean
Online Access:https://doi.org/10.1029/2001GL013023
http://ecite.utas.edu.au/26316
Description
Summary:During the 13 day Southern Ocean Iron RElease Experiment (SOIREE), dissolved iron concentrations decreased rapidly following each of three iron-enrichments, but remained high (> 1 nM, up to 80% as FeII) after the fourth and final enrichment on day 8. The former trend was mainly due to dilution (spreading of iron-fertilized waters) and particle scavenging. The latter may only be explained by a joint production-maintenance mechanism; photoreduction is the only candidate process able to produce sufficiently high FeII, but as such levels persisted overnight (8 hr dark period) - ten times the half-life for this species - a maintenance mechanism (complexation of FeII) is required, and is supported by evidence of increased ligand concentrations on day 12. The source of these ligands and their affinity for FeII is not known. This retention of iron probably permitted the longevity of this bloom raising fundamental questions about iron cycling in HNLC (High Nitrate Low Chlorophyll) Polar waters.

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