Cation binding in a mor layer: batch experiments and modelling
2003 (English)In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 54, no 2, 295-310 p.Article in journal (Refereed) Published
The understanding of cation binding in the mor layer is important to correctly assess the biogeochemical cycling of metals and other cations in forested ecosystems. In a series of batch experiments, the binding of cations was examined in two mor layers from central Sweden. We examined the effect of Ca and Al on the binding of Zn, and also the binding of added Pb, Cu and Cd. Two models, WinHumicV and the Stockholm Humic Model (SHM), were tested for their ability to describe the data obtained. We found that for Zn, the pH at 50% sorption was increased from 2.8 to 4.2 after the addition of 3 mM Al. The proton titration data were well described by both WinHumicV and SHM after optimization of the concentrations of 'active' Al and humic substances. Applying generic parameters for cation binding produced deviations between the model simulations and the observations, particularly for the dissolved Pb and Cu concentrations, which were underestimated. A revised set of cation complexation constants was presented that improved the fit, particularly for SHM. For WinHumicV, there were still poor overall fits. The difference in model performance may be due to the greater number of adjustable parameters in the SHM, but probably also to other model-specific differences. According to the SHM simulations, the binding of Ca, Mg and Mn was mainly non-specific, whereas Pb, Cu and Al were bound as mono- or bidentate complexes. For Zn and Cd, binding occurred through both counter-ion accumulation and monodentate complexation.
Place, publisher, year, edition, pages
2003. Vol. 54, no 2, 295-310 p.
quickly reacting aluminum, metal-ion binding, humic substances, organic-matter, soil horizons, solubility, acid, adsorption, protons, system
IdentifiersURN: urn:nbn:se:kth:diva-22522ISI: 000183032200009OAI: oai:DiVA.org:kth-22522DiVA: diva2:341220
QC 201005252010-08-102010-08-10Bibliographically approved