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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/732

Title: Iron enrichment and photoreduction of iron under UV and PAR in the presence of hydroxycarboxylic acid: implications for phytoplankton growth in the Southern Ocean
Authors: Ozturk, M
Croot, PL
Bertilsson, S
Abrahamsson, K
Karlson, B
David, R
Fransson, A
Sakshaug, E
Keywords: Equatorial pacific-ocean
Sub-arctic pacific
Surface waters
Trace-metals
Seawater
Blooms
Issue Date: 2004
Publisher: Pergamon-Elsevier Science Ltd
Citation: Ozturk, M, et al. 2004. Iron enrichment and photoreduction of iron under UV and PAR in the presence of hydroxycarboxylic acid: implications for phytoplankton growth in the Southern Ocean. Deep-Sea Research Part II-Topical Studies in Oceanography, vol. 51(22/24), pp 2841-2856
Abstract: Iron (III) photoreduction and the responses of phytoplankton under ultraviolet (UV) and photosynthetically available radiation (PAR) were investigated with the presence of hydroxycarboxylic acid (glucaric acid (GA), a model compound for organic acids excreted by phytoplankton). The incubation experiments were carried out on board using seawater samples collected in the location of the winter ice edge (WIE) and the spring ice edge (SIE) of the Southern Ocean. In this paper, we focus on the results of experiment in WIE. Throughout the experiments, dissolved Fe (II), major nutrients and in vivo fluorescence were monitored regularly. In addition, Chl-a, POC/PON, cell densities of phytoplankton and bacteria, bacterial production, organic peroxide, hydrogen peroxide and total CO2 were measured. The results from the WIE show that iron enrichment had a substantial effect on phytoplankton growth rate. Fe (III) addition in the presence of GA (FeGA) gave higher Fe (II) concentration and higher growth rate of phytoplankton than those in controls. Our results suggest that hydroxycarboxylic acid had a significant chemical and biological impact. The presence of GA influenced iron photochemistry and iron availability to phytoplankton. Phytoplankton growth responses to iron enrichments in incubations under UV and PAR were completely dissimilar. It seems that FeGA addition prominently changes the harmful effect of UV on the phytoplankton population. This study provides preliminary information on how the photoreduction of iron (III) and the phytoplankton growth are affected by iron enrichment in the presence of hydroxycarboxylic acid.
Description: Copyright: 2004 Pergamon-Elsevier Science Ltd
URI: http://hdl.handle.net/10204/732
ISSN: 0967-0645
Appears in Collections:Analytical science
Coastal and marine systems
General science, engineering & technology

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