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Parameterization and regionalization of Cd sorption characteristics of sandy soils. I. Freundlich type parameters

1998; Wiley; Volume: 161; Issue: 6 Linguagem: Inglês

10.1002/jpln.1998.3581610612

0044-3263

Günther Springob, Jürgen Böttcher,

Composting and Vermicomposting Techniques

Abstract Cd sorption isotherms (n = 24) were established for arable, sandy soils of the ‘Fuhrberger Feld’ catchment area northeast of Hannover (Germany) using 0.01 M c Ca(NO 3 ) 2 solution with Cd additions ranging from 0 to 44 μM c Cd. Alternative fractions of initially (prior to analysis) sorbed Cd (S 0 ) were added to the amount sorbed during the experiments. The Freundlich equation was fitted to the resulting isotherms. The obtained retention parameters k and M varied with respect to the different S 0 fractions. Isotherms corrected with Cd EDTA as S 0 fraction were nonlinear in their log‐form. The highest degree of log‐linearity is obtained if S 0 is characterized by 40% of the agua regia extractable Cd. The corresponding k values ranged from 36 to 1275 g 1‐M L M kg −1 (mean 338 g 1‐M L M kg −1 , cv = 92%). The Freundlich exponent M showed less variation (0.7 to 1.1, cv = 12%) with a mean of 0.88. Functions based on these parameters predicted Cd concentrations in Ca(NO 3 ) 2 −soil suspensions well (r 2 = 0.96) but were hardly related to Cd concentrations of ‘fresh’ soil solutions (r 2 = 0.20).