Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/66376
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Type: Journal article
Title: Labile Cd complexes increase Cd availability to plants
Author: Degryse, J.
Smolders, E.
Merckx, R.
Citation: Environmental Science & Technology, 2006; 40(3):830-836
Publisher: Amer Chemical Soc
Issue Date: 2006
ISSN: 0013-936X
1520-5851
Statement of
Responsibility: 
Fien Degryse, Erik Smolders, and Roel Merckx
Abstract: Dissolved trace metals are present in the environment as free ions and as complexes. Commonly used models to predict metal bioavailability consider the free ion as the major bioavailable species. However, increases in metal availability in the presence of metal complexes have repeatedly been found. We measured the uptake of cadmium (Cd) by spinach (Spinacia oleracea) from solution in absence or presence of synthetic ligands. At the same free ion concentration, the uptake of Cd ranged over almost 3 orders of magnitude and was largest in treatments with fast dissociating (i.e. labile) complexes. Similar results were found for the diffusional fluxes in these solutions, as measured with the DGT technique. The observed effect of Cd complexes on the plant uptake was in agreement with model calculations in which plant uptake was assumed to be governed by the diffusional flux. These results strongly suggest that Cd uptake is rate-limited by diffusion of the free ion to the root surface, even in stirred solutions. As a result, dissolved Cd complexes can increase Cd uptake, resulting in apparent exceptions from the free ion activity model. The magnitude of this increase depends both on the concentration and on the lability of the complexes. The free ion concept should therefore be reconsidered when transport limitations of the metal ion to the uptake site prevail.
Keywords: Spinacia oleracea; Plant Roots; Cadmium; Soil Pollutants; Diffusion; Biological Availability; Models, Theoretical; Forecasting
Rights: Copyright © 2006 American Chemical Society
RMID: 0020106329
DOI: 10.1021/es050894t
Appears in Collections:Agriculture, Food and Wine publications

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