Mechanisms of Chelate Formation during Organo-mineral Melioration of Heavy Metals Polluted Acid Soils (I)

T. RAYCHEV1, A. ARSOVA1, S. POPANDOVA1, G. JOZEFACIUK2, Z. SOKOLOWSKA2 and M. HAJNOS2
1 N. Poushkarov Institute of Soil Science, BG-1080 Sofia, Bulgaria
2 Institute of Agrophysics, Polish Academy of Sciences, 4 Doswiadczalna Str., P.O. Box 201, 20-209 Lublin, Poland

Abstract

RAYCHEV, T., A. ARSOVA, S. POPANDOVA, G. JOZEFACIUK, Z. SOKOLOWSKA and M. HAJNOS, 2001. Mechanisms of chelate formation during organo-mineral melioration of heavy metals polluted acid soils (I). Bulg J. Agric. Sci., 7: 43-47

The study performs a theoretical discussion on the different mechanisms of chelate formation during organo-mineral liming of heavy metals polluted soils. The effect of the formation of complex heteropolar salts of the aluminum – humus compounds with Ca2+ ions is analyzed and schematically illustrated in respect to the calcium mobility and soil reaction.
According to the theoretical analysis of the relations among the different components in the chelate formation processes one can state that: the phenolic hydroxyl groups, amount of which is generally equal to this of the carboxyls in the molecules of highly humified organic compounds, buffer the relative excess of lime thus counteracting the effect of overliming; the relative deficiency of calcium ions preserves the participation of these groups in complex heteropolar salts, that indicates the dynamic character of the phenolic hydroxyls in the organo-mineral reactions; the depletion of the intra-molecular rearrangement reactions in the anionic part of the organic molecules can lead to the formation of organo-mineral adsorption complexes via polyvalent cationic bridges. The effect of this is a decrease of ion-exchange reactions between soil adsorbent and the plant root system.

Key words: acid soils, liming, organo-mineral melioration, heavy metal pollution, chelate formation