A chemical method for estimating the availability of iron to phytoplankton in seawater

A technique that employs the complexing agent 8-hydroxyquinoline (oxine) to measure a labile portion of total Fe in seawater was used to test the hypothesis that the biological availability of colloidal Fe is a direct function of its chemical lability. Three colloidal ferrihydrites (amorphous FeOOH)...

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Bibliographic Details
Published in:Marine chemistry 1991, Vol.33 (1), p.23-40
Main Authors: Wells, M.L, Mayer, L.M, Guillard, R.R.L
Format: Article
Language:English
Subjects:
Marine
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Summary:A technique that employs the complexing agent 8-hydroxyquinoline (oxine) to measure a labile portion of total Fe in seawater was used to test the hypothesis that the biological availability of colloidal Fe is a direct function of its chemical lability. Three colloidal ferrihydrites (amorphous FeOOH) were examined for their lability in seawater and for their ability to support growth of three species of neritic phytoplankton ( Thalassiasira pseudonana, Isochrysis galbana and Dunaliella terriolecta). Earlyphase (freshly precipitated) ferrihydrite was ∼65% oxine-labile and proved to be an excellent source of available Fe, as determined by organism growth. Limited heating of this ferrihydrite, which accelerates low-temperature aging processes similar to those operating in nature, caused sharp decreases in both the algal growth responses and in the oxine-lability of the ferrihydrite. The correspondence between colloid lability and organism growth in culture suggests that Fe availability is related strongly to its chemical lability. It thus appears that the oxine technique provides an operational method for estimating the biological availability of Fe in seawater.
ISSN:0304-4203
1872-7581
DOI:10.1016/0304-4203(91)90055-2