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Cadmium Sorption and Desorption in Limed Topsoils as Influenced by pH: Isotherms and Simulated Leaching
Author(s) -
Filius Angelika,
Streck Thilo,
Richter Jörg
Publication year - 1998
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1998.00472425002700010003x
Subject(s) - sorption , desorption , chemistry , cadmium , freundlich equation , adsorption , soil water , environmental chemistry , leaching (pedology) , analytical chemistry (journal) , soil science , geology , organic chemistry
The influence of pH on cadmium (Cd) sorption and desorption isotherms was studied in sandy and clayey soils of northern Germany. Seventeen topsoils from four long‐term lime amendment experiment plots ranging in pH from 4.1 to 6.9 were collected. Batch adsorption isotherms demonstrated the strong influence of pH on Cd sorption behavior. Cadmium sorption increased with pH, even within a very narrow range of pH values (ΔpH ≈ 0.3). The experimental desorption isotherms, which were determined by widening the soil/solution ratio, differed markedly from the adsorption isotherms. Differences decreased when reaction time for desorption was prolonged. The data for Cd adsorption and desorption were pooled to derive the coefficients of a generalized Freundlich‐type expression S = S ( C M ) including soil pH in 0.01 M CaCl 2 and organic C content (oc) (% by mass) ( S = k * (H + ) a oc b C M ). Sorption isotherms were used for simulations to predict vertical displacement of Cd in the field. The simulations using measured field mean concentration profiles S ( z ) as initial values, showed Cd adsorption isotherms to be appropriate for describing longer‐term desorption equilibria.