Pot and adsorption-exchange experiments were carried out by collecting the soil samples from the surface layer(0-15cm) of red soil at the Ecological Experiment Station of Red Soil,the Chinese Academy of Sciences,in Jiangxi Province of CHina.When concentration of the exogenous La^3+ exceeded 400mg kg^-1,there was less non-exchangeable La^3+ than exchangeable La^3+ in the soil.Cation exchagne capacity of the soil changed slightly with increasing concentration of the exogenous La^3+ in both experiments.However,in the adsorption-exchange experiment,when concentration of the exogenous La^3+ was higher than 300mg kg^-1,exchangeable basic cations decreased significantly,while exchangeable hydrogen and exchangeable aluminum increased significantly compared with the control treatments.The amounts of base cations(Ca^2+,Mg^2+,k^+and Na^+)exchanged by La^3+ in the supernatant solution increased with the concentration of the exogenous La^3+,especially when concentration of the exogenous La^3+ was higher than 50mg kg^-1.
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