Selenitadsorption an Waldhumusformen

Adsorption of selenite on different types of forest humus In the present investigation the adsorption of selenite selenium on L-, O-, and A-horizons of the humus forms mull, moder, and mor was studied. Selenite adsorption decreased in the order mull > moder > mor. The organic layers adsorbed nearly the same amount of selenium as the underlying A-horizons. Among the L- and O-layers selenadsorption increased with increasing pH. Amounts of organic carbon, “free” oxides did not influence the adsorption capacity. The Freundlich equation was valid to describe selenite adsorption of all layers under investigation. Additionally the Langmuir equation fitted the adsorption curves of the mull soil and the moder L-horizon. Adsorption experiments using perfusion apparatuses showed microorganismus to incorporate high amounts of selenite under natural conditions.