Interaction of Cd and citric acid, EDTA in red soil

Adsorption and desorption process of cadmium in red soil (Ferrisols) as well as the influence by media's pH were investigated in detail with and without citric acid and EDTA. Experimental results clearly showed that Cd adsorption in red soil was affected significantly by the coexisted organic chemicals. In the presence of citric acid and EDTA, Cd adsorption in red soil increased with pH in acid media but decreased in high pH one. Further studies placed stress on the adsorbed Cd in red soil which was found to be existed mainly as exchangeable one at pH<5 5, and desorption rate by 0 10 mol/L NaNO 3 gave a peak shaped curve due to the difference of specifically and nonspecifically adsorbed Cd with pH's change.