title: Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.
abstract: Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies.
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France. Electronic address: arnaud.schneider@univ-reims.fr.
authors.forename: Arnaud R
authors.initials: AR
authors.lastname: Schneider
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Ponthieu
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Cancès
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Conreux
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Morvan
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Gommeaux
authors.affiliation: Université de Reims Champagne-Ardenne, GEGENAA, EA 3795, 2 Esplanade Roland Garros, 51100 Reims, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Marin
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154, CNRS, F-75005 Paris, France.
authors.forename: Marc F
authors.initials: MF
authors.lastname: Benedetti
mesh_terms: D004784:Environmental Monitoring; D006812:Humic Substances / Q000032:analysis*; D017895:Manganese Compounds / Q000032:analysis*; D008670:Metals / Q000737:chemistry*; D008962:Models, Theoretical; D010087:Oxides / Q000032:analysis*; D012989:Soil Pollutants / Q000737:chemistry*; D014131:Trace Elements / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D017895:Manganese Compounds; D008670:Metals; D010087:Oxides; D012989:Soil Pollutants; D014131:Trace Elements; C027424:manganese oxide
keywords: Fulvic acids; LMWOA; Manganese oxides; Modelling; Soil solution; Trace elements