HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Lehto, N. J. Articles by Tych, W. Search for Related Content PubMed PubMed Citation Articles by Lehto, N. J. Articles by Tych, W. Agricola Articles by Lehto, N. J. Articles by Tych, W. Related Collections Soil Kinetics Heavy Metals Plant and Soil Interactions

TECHNICAL REPORTS

Plant and Environment Interactions

Theoretical Comparison of How Soil Processes Affect Uptake of Metals by Diffusive Gradients in Thinfilms and Plants

Environmental Science Department, Lancaster University, Bailrigg, Lancaster, LA1 4YQ

^* Corresponding author (w.davison{at}lancaster.ac.uk)

Received for publication November 5, 2005. The theoretical basis for using measurements of metal uptake by the technique of diffusive gradients in thinfilms (DGT) to mimic processes in soils that affect uptake of metals by plants is examined. The uptake of metals by plants and DGT were compared conceptually and quantitatively by using the classic Barber model of plant uptake and the DIFS (DGT-induced fluxes in soils) model of uptake by DGT. For most metals and plants considered, uptake fluxes were similar to those induced by DGT using the most common gel layer thicknesses of 0.2 to 2mm. Consequently DGT perturbs the chemical equilibrium of metals in the soil solution and between soil solution and solid phase, to a similar extent to plants, and therefore induces a similar balance in supply by diffusion and by release from the solid phase. DIFS was used to show that desorption kinetics, which are not considered by the plant uptake model, are likely important for uptake when the capacity of the soil solid phase is large. Model calculations showed that mass flow into a plant root would only contribute appreciably to the total flux of metal under circumstances when the solid phase reservoir of metal was very low. Generally, however, DGT is likely to emulate supply processes from the soil that govern uptake of metal by plants. Exceptions are likely to be found in poorly buffered soils (typically sandy and/or low pH), and at very high concentrations of metals in soil solution, such that the soil solution concentration at the plant root interface is higher than the Michaelis-Menten constant (K_m).

Abbreviations: DGT, diffusive gradients in thinfilms • DIFS, DGT-induced fluxes in soils • K_d, solid-solution phase partitioning coefficient • T_c, time needed for the partitioning components of K_d to reach 63% of their equilibrium values, assuming the solution concentration is initially zero • K_m, Michaelis-Menten constant • I_max, maximum flux of ions into a root • C_E, effective concentration