Concentration of Ionic Copper in Soil Solution

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Abstract
The ecological relevance of heavy metals in soils cannot accurately be judged by the total metal content, although it is the best indicator for the degree of metal saturation of a given soil. However, metal concentration and metal forms in soil solution are of great significance for assessment of their impact on plants and soil microorganisms. Soil solution has been simulated by a neutral salt extract (i.e. NaNO3) of soil. Prediction of metal impact on a given plant and on the growth and activities of soil microorganisms could be made with a satisfactory accuracy irrespective of large differences in physiobiochemical properties of soils. In order to improve the accuracy of such prediction, it is very important to understand the distribution of a metal in soil solution. With the help of analytical techniques like atomic absorption spectroscopy and ion chromatography, it is possible to differentiate three following operational forms of a metal in a given soil solution: (1) Total soluble; (2) Ionic and labile charged complexes; (3) Molecular and uncharged complexes. The results show that the total soluble copper in fourteen investigated vineyards soils range between 0.5 to 1.85 mg/kg soil. The ionic copper as percent of the total soluble copper varied between 36 to 68%. Because pH values of these soils were very close to each other, it is reasonable to assume that the large variation in ionic copper could be due to differences in the soluble organic ligands concentration in these soils. Further research work is needed to show the relevance of forms of copper for the growth of vineyards and soil microorganisms.