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Apparent cation‐exchange equilibria in podzolic forest soils
Author(s) -
Nissinen A.,
Ilvesniemi H.,
Tanskanen N.
Publication year - 1998
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1046/j.1365-2389.1998.00136.x
Subject(s) - chemistry , cation exchange capacity , soil water , selectivity , ion exchange , partition coefficient , analytical chemistry (journal) , inorganic chemistry , mineralogy , environmental chemistry , ion , chromatography , geology , soil science , organic chemistry , catalysis
Summary The Gaines–Thomas selectivity coefficient, K , was used to express the relation between the cations in solution and the cations in exchange sites in podzolic forest soils. Soil solution was obtained by centrifuging a fresh bulked soil sample. Exchangeable cations HX, AlX, CaX, MgX and KX and effective cation‐exchange capacity, CEC e , were determined with 0.1 m BaCl 2 . Apparent values of K indicated a preference of Ca 2+ over Mg 2+ and over Al 3+ in O, A and B horizons (log K Al–Ca < 0 and log K Mg–Ca < 0), whereas log K K–Ca and log K H–Ca exceeded zero. The horizons were similar with respect to log K H–Ca , and the differences in log K Mg–Ca were small. Log K K–Ca and log K Al–Ca increased in the horizons in the order O < A < B. Log K Al–Ca was not significantly correlated with the fraction AlX/CEC e . Log K Mg–Ca was positively correlated with the fractions HX/CEC e and AlX/CEC e , and negatively correlated with log (CaX/MgX). The selectivity coefficient of binary cation exchange seemed to be applicable to in situ soil solutions. However, the fraction of each cation on exchange sites should be based on the CEC e rather than on the sum of the two cations. The latter, also, seemed to be acceptable in cases of exchangeable cations with a large relative content in soil, e.g. in Al 3+ –Ca 2+ exchange in A and B horizons, and in H + –Ca 2+ exchange in O and A horizons.