Comparison of different methods for generating desorption isotherms of Cd and Pb in two soils of different contaminant loading

摘要

Desorption isotherms describe the partitioning of metals between the soil solid and solution and provide basic information for rhizosphere modelling. This study was conducted to compare different methods for examination of the Cd and Pb desorption behavior in two contaminated, calcareous top soils. Desorption isotherms of Cd and Pb showed mainly irregular parabolic and sigmoidal shape in the moderately contaminated soil. Artefacts due to breakdown of soil microaggregates in batch experiments were charged for introduction of new sorption surfaces and, hence, varying steady state conditions of the system. Observed effects are challenging the suitability of desorption isotherms performed by batch experiments with soils of high aggregate stability and/or low loading of the target element.