Characteristic of Cd sorption in the copper tailings wasteland soil by amended dissolved organic matter from fresh manure and manure compost

Abstract

The aim of this study was to investigate the effects of dissolved organic matter (DOM) from fresh manure and its
compost on the sorption of Cd on copper tailings wasteland and normal farmland soils, in Tongling City, China. In the
presence of DOM, Cd sorption capacity decreased markedly for both soils, especially for the copper tailings
wasteland. The Cd sorption isotherms could be well described by the Freundlich equation (r2 = 0.98), and the binding
intensity parameter of soils in the presence of fresh manure DOM was lower than compost DOM. An increase in DOM
concentration significantly reduced the sorption of Cd by both soils. Within the Cd and DOM concentration range
studied, the decrease in Cd sorption caused by fresh manure DOM was consistently greater than that of compost
DOM. Moreover, the reduction of Cd sorption caused by DOM was more obvious in the soil with higher pH. In addition,
the sorption of Cd increased with an increase in pH for both soils without the addition of DOM, while Cd sorption in
the presence of DOM was unexpectedly decreased with an increase in pH at a pH >6.6.