title: Modelling metal accumulation using humic acid as a surrogate for plant roots.
abstract: Metal accumulation in roots was modelled with WHAM VII using humic acid (HA) as a surrogate for root surface. Metal accumulation was simulated as a function of computed metal binding to HA, with a correction term (E(HA)) to account for the differences in binding site density between HA and root surface. The approach was able to model metal accumulation in roots to within one order of magnitude for 95% of the data points. Total concentrations of Mn in roots of Vigna unguiculata, total concentrations of Ni, Zn, Cu and Cd in roots of Pisum sativum, as well as internalized concentrations of Cd, Ni, Pb and Zn in roots of Lolium perenne, were significantly correlated to the computed metal binding to HA. The method was less successful at modelling metal accumulation at low concentrations and in soil experiments. Measured concentrations of Cu internalized in L. perenne roots were not related to Cu binding to HA modelled and deviated from the predictions by over one order of magnitude. The results indicate that metal uptake by roots may under certain conditions be influenced by conditional physiological processes that cannot simulated by geochemical equilibrium. Processes occurring in chronic exposure of plants grown in soil to metals at low concentrations complicate the relationship between computed metal binding to HA and measured metal accumulation in roots.
authors.affiliation: Department of Environmental Science, Radboud University Nijmegen, The Netherlands; Department of Aquatic Ecology, Faculty of Biology, University of Duisburg-Essen, Germany. Electronic address: Yen.Le@uni-due.de.
authors.forename: T T Yen
authors.initials: TT
authors.lastname: Le
authors.affiliation: National Institute for Public Health and the Environment, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Swartjes
authors.affiliation: Alterra, Wageningen University and Research Centre, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Römkens
authors.affiliation: Alterra, Wageningen University and Research Centre, The Netherlands.
authors.forename: Jan E
authors.initials: JE
authors.lastname: Groenenberg
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, Australia.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Lofts
authors.affiliation: Department of Environmental Science, Radboud University Nijmegen, The Netherlands.
authors.forename: A Jan
authors.initials: AJ
authors.lastname: Hendriks
mesh_terms: D004785:Environmental Pollutants / Q000378:metabolism*; D007887:Fabaceae / Q000378:metabolism; D006812:Humic Substances; D008129:Lolium / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D008954:Models, Biological; D018532:Pisum sativum / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D006812:Humic Substances; D008670:Metals; D012989:Soil Pollutants
keywords: Affinity; Metal; Modelling; Root uptake; WHAM