Enhancement of the reactive iron pool by marine diatoms

Rijkenberg, Micha J.A., Gerringa, Loes J.A., Timmermans, Klaas R., Fischer, Astrid C., Kroon, Koos J., Buma, Anita G.J., Wolterbeek, Bert Th. and de Baar, Hein J.W. (2008) Enhancement of the reactive iron pool by marine diatoms. Marine Chemistry, 109, (1-2), 29-44. (doi:10.1016/j.marchem.2007.12.001).


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Short term (2 days) laboratory experiments were performed to study the change in irradiance induced production of Fe(II) in
seawater in the presence of two open oceanic Southern Ocean diatom species, Thalassiosira sp. and Chaetoceros brevis. Three irradiance conditions were applied: 1) UVB+UVA+VIS, 2) UVA+VIS, and 3) VIS, and Fe concentrations of 0 and 5 nM Fe were added to natural Southern Ocean seawater (containing 0.32 nM dissolved Fe and 1.69 equivalents of nM L?1 Fe dissolved organic ligands, log K?=22.03). The photoproduced concentration of Fe(II) showed no relationship with the concentration of total dissolved Fe or the concentration of strongly chelated iron. During incubations with the diatoms an increase in the Fe(II) concentration during the second day suggested a modification of the Fe speciation. In the presence of Thalassiosira sp. photoreduction of Fe(III) was observed, whereas in the presence of C. brevis irradiance independent Fe(III) reduction played an important role in the Fe(II) production. Furthermore, a decrease in the strongly chelated Fe concentration, in concert with a decrease in the conditional stability constant, suggested a modification of the strongly chelated Fe fraction in the experiments with C. brevis. The chelated Fe fraction did not change in cultures with Thalassiosira sp. Overall, the presence of diatoms appeared to
enhance the reactive Fe pool improving the biological availability of Fe.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1016/j.marchem.2007.12.001
ISSNs: 0304-4203 (print)
Related URLs:
Keywords: photoreduction, phytoplankton, diatoms, iron limitation, bioavailability, climate change, southern ocean
Subjects: Q Science > QD Chemistry
Q Science > QR Microbiology
G Geography. Anthropology. Recreation > GC Oceanography
Divisions : University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 50855
Accepted Date and Publication Date:
16 February 2008Published
3 April 2007Submitted
Date Deposited: 09 Apr 2008
Last Modified: 31 Mar 2016 12:28
URI: http://eprints.soton.ac.uk/id/eprint/50855

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