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Retention of dissolved iron and Fe II in an iron induced Southern Ocean phytoplankton bloom
Author(s) -
Croot Peter L.,
Bowie Andrew R.,
Frew Russell D.,
Maldonado Maria T.,
Hall Julie A.,
Safi Karl A.,
La Roche Julie,
Boyd Philip W.,
Law Cliff S.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013023
Subject(s) - bloom , phytoplankton , nitrate , environmental chemistry , chemistry , algal bloom , ligand (biochemistry) , nutrient , oceanography , geology , biochemistry , receptor , organic chemistry
During the 13 day Southern Ocean Iron RE‐lease Experiment (SOIREE), dissolved iron concentrations decreased rapidly following each of three iron‐enrichments, but remained high (>1 nM, up to 80% as Fe II ) 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 Fe II , but as such levels persisted overnight (8 hr dark period) —ten times the half—life for this species—a maintenance mechanism (complexation of Fe II ) is required, and is supported by evidence of increased ligand concentrations on day 12. The source of these ligands and their affinity for Fe II 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.