Quantification of vanadium adsorption by German soils

Vanadium adsorption by soils representing different soil types from Germany has been studied. For 30 soils ‘Freundlich’ type sorption isotherms have been deduced from laboratory vanadium(V) adsorption experiments. The native adsorbed vanadium quantity of a soil (S0) and the Freundlich parameters m and log k have been determined by non linear regression of the experimental data to the Freundlich model. Pronounced differences in vanadium adsorption of different soils exist and could be quantified. The vanadium adsorption data could be generalized by grouping the soils into four classes according to their vanadium adsorption properties. For each class (sandy soils, top soils, sub soils with pH < 5.5, and sub soils with pH > 5.5) mean Freundlich parameters m and log k have been calculated to be 0.59, 0.72, 0.52, 0.57 and 2.55, 2.89, 4.29, 3.41, respectively. These parameters can be used to estimate vanadium sorption properties of soils for which no vanadium sorption experiments are available. Aqua regia soluble vanadium contents of the studied soils (range 1.7–143 mg/kg; median 32 mg/kg) and leached vanadium concentrations from experiments without vanadium addition (range 0.08–37 µg/l; median 2.1 µg/l) are also given.