Mutual Influence of Cu and a Cationic Herbicide on Their Adsorption-Desorption Processes on Two Selected Soils |
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| Authors: | Undabeytia T Morillo E Ramos A B Maqueda C |
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| Institution: | 1. Instituto de Recursos Naturales y Agrobiología (C.S.I.C.), 41080, Sevilla, Spain
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| Abstract: | Adsorption of Cu and the cationic herbicide chlordimeformwas carried out on two acidic soils (S-48 and LM).Chlordimeform adsorption occurred by cationic exchange andwas higher on LM soil due to its higher CEC, partlyassociated to the presence of vermiculite. Cu adsorptionwas also higher on LM soil and was related to its higheriron and manganese oxides content. The presence of theherbicide in solution always decreased Cu adsorption on S-48 soil, but on LM soil the amount of Cu adsorbed onlydecreased at the highest concentrations used. This togetherwith the lower amounts of Cu desorbed from LM soil afterfive successive desorptions in comparison to S-48 soil,indicates that Cu was being mostly adsorbed on oxides whichexhibit a very high affinity for the heavy metal. Themaximal amount of Cu desorbed on both soils only reached upto 13% of the amount adsorbed. Chlordimeform adsorption decreased in the presence of Cu as aresult of its competition for the adsorption sites on bothsoils. Cu competition on LM soil was not so strong as on S-48 soil due to the higher adsorption of the heavy metal onoxides, for which the herbicide’s affinity is not so high. Thelower the amounts of chlordimeform adsorbed on both soilsthe higher its desorption percentage. This was attributedto steric impediment of chlordimeform molecule itself forthe desorption from lamellar silicates. |
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