A QICAR approach for quantifying binding constants for metal-ligand complexes |
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Authors: | Zhou Dong-Mei Li Lian-Zhen Peijnenburg Willie J G M Ownby David R Hendriks A Jan Wang Peng Li Dan-Dan |
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Affiliation: | a State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No.71 East Beijing Road, Nanjing 210008, China b National Institute of Public Health and the Environment, Laboratory for Ecological Risk Assessment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands c Institute of Environmental Sciences (CML), Leiden University, Leiden, The Netherlands d Department of Chemistry, Towson University, Towson, MD 21252, USA e Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, P.O. Box 9010, NL-6500 GL, Nijmegen, The Netherlands |
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Abstract: | Relative metal-ligand complex stability is predicted by evaluating the relationships between physicochemical properties of metal ions and their experimental biotic and abiotic binding constants, K. Linear regression analysis showed that the softness index (σp) and the covalent index (χ2mr) were especially useful in model construction for rainbow trout (Oncorhynchus mykiss), fathead minnows (Pimephales promelas) and crustaceansaquatic (Daphnia magna) based on RMSE and F-ratio criterion (Fobserved/Fcritical of ≥4). The absolute value of the log of the first hydrolysis constant |log KOH| correlated best with log K values for barley (R2=0.74, p=0.02) and earthworm (R2=0.82, p=0.01). In contrast, the ionic index Z2/r explained most of the variability of log K values for the two clays kaolinite and montmorillonite, while |log KOH| was a better predictor of the generic NICA-Donnan parameters for HA and FA (0.67<R2<0.80, 0.002<p<0.01). This implies dissimilarity of the nature of the binding sites on biotic and chemical ligands and the different binding mechanisms between metal and ligands. |
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Keywords: | Metal QICAR Metal binding Binding constant Biotic ligand Metal sorption |
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