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Titel (primär) LFERs for soil organic carbon-water distribution coefficients (KOC) at environmentally relevant sorbate concentrations
Autor Endo, S.; Grathwohl, P.; Haderlein, S.B.; Schmidt, T.C.;
Journal / Serie Environmental Science & Technology
Erscheinungsjahr 2009
Department AUC;
Band/Volume 43
Heft 9
Sprache englisch;
Abstract Organic carbon-water distribution coefficients, K-OC, for organic compounds at environmentally relevant, low sorbate concentrations may substantially differ from those at higher concentrations due to nonlinear sorption to soil organic matter. However, prediction methods for K-OC such as linear free energy relationships (LFERs) are currently only available for high sorbate concentrations (i.e., near solubility limits), reflecting the lack of a set of consistent experimental data in an environmentally more relevant concentration range (i.e., orders of magnitude lower than solubilities). In this study, we determined K-OC for two model sorbents of soil organic matter, peat and lignite, at sorbate concentrations of 4.3 and 19 mg/kg-organic-carbon, respectively, in batch suspensions. The measured K-OC values for organic sorbates (51 for peat, 58 for lignite) of varying sizes and polarities were modeled successfully with polyparameter linear free energy relationships (PP-LFERs). The resulting PP-LFER for peat was significantly different from the PP-LFERs in the literature determined at near aqueous solubility limits of sorbates. The literature PP-LFERs were found to underestimate the measured K-OC values for peat at the low concentration by up to 1 order of magnitude. The extent of underestimation highly depends on the sorbate properties and can be explained by differing sorption nonlinearities of the sorbates as predicted by a reported empirical relationship between the nonlinearity in peat and the sorbate dipolarity/polarizability parameter S. Lignite appears to be a stronger sorbent toward many sorbates than typical soil organic matter irrespective of the concentration range and thus may not be representative for organic matter with regard to the magnitude of K-OC. The present study offers the first PIP-LIFER equation for log K-OC in soil organic matter at typical environmental sorbate concentrations
ID 151
dauerhafte UFZ-Verlinkung https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=151
Endo, S., Grathwohl, P., Haderlein, S.B., Schmidt, T.C. (2009):
LFERs for soil organic carbon-water distribution coefficients (KOC) at environmentally relevant sorbate concentrations
Environ. Sci. Technol. 43 (9), 3094 - 3100