Title: Iron colloids reduce the bioavailability of phosphorus to the green alga Raphidocelis subcapitata
Authors: Baken, Stijn ×
Nawara, Sophie
Van Moorleghem, Christoff
Smolders, Erik #
Issue Date: 1-Aug-2014
Publisher: Pergamon Press
Series Title: Water Research vol:59 pages:198-206
Abstract: Phosphorus (P) is a limiting nutrient in many aquatic systems. The bioavailability of P in natural waters strongly depends on its speciation. In this study, structural properties of iron colloids were determined and related to their effect on P sorption and P bioavailability. The freshwater green alga Raphidocelis subcapitata was exposed to media spiked with radiolabelled 33-PO4, and the uptake of 33-P was monitored for 1 h. The media contained various concentrations of synthetic iron colloids with a size between 10 kDa and 0.45 μm. The iron colloids were stabilised by natural organic matter. EXAFS spectroscopy showed that these colloids predominantly consisted of ferrihydrite with small amounts of organically complexed Fe. In colloid-free treatments, the P uptake flux by the algae obeyed Michaelis-Menten kinetics. In the presence of iron colloids at 9 or 90 μM Fe, corresponding to molar P:Fe ratios between 0.02 and 0.17, the truly dissolved P (<10 kDa) was between 4 and 60% of the total dissolved P (<0.45 μm). These colloids reduced the P uptake flux by R. subcapitata compared to colloid-free treatments at the same total dissolved P concentration. However, the P uptake flux from colloid containing solutions equalled that from colloid-free ones when expressed as truly dissolved P. This demonstrates that colloidal P did not contribute to the P uptake flux. It is concluded that, on the short term, phosphate adsorbed to ferrihydrite colloids is not available to the green alga R. subcapitata.
ISSN: 0043-1354
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division Soil and Water Management
× corresponding author
# (joint) last author

Files in This Item:
File Description Status SizeFormat
Baken2014-Colloidal P availability OA article final.pdfOA article Published 460KbAdobe PDFView/Open
Baken2014-supinf.docxsupplementary material Published 292KbMicrosoft WordView/Open


All items in Lirias are protected by copyright, with all rights reserved.

© Web of science