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International Agrophysics
wydawca:Instytut Agrofizyki
im. B. Dobrzańskiego
PAN
w Lublinie
ISSN: 0236-8722


vol. 16, nr. 3 (2002)

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Structural and Zn-binding features of ortho- and pyrophosphate modified soil metal-humus sorbents (Features of P-modified humus sorbents)
(pobierz wersję PDF)
Kudeyarova A.Yu.
Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, 142290 Pushchino Moscow Region, Russia

vol. 16 (2002), nr. 3, pp. 197-202
streszczenie The results of the experiments showed that the P treatment considerably enhanced the Zn-binding capability of acid soil. The contribution of ortho- and pyro-P to Zn binding was that they changed the structure of humus ligands in the sorbing metal-humus complexes. This was clearly demonstrated with the Fe-HA complex as a simulator of soil sorbent. New double carbon- carbon and phosphorus-oxygen bonds were discovered in the P-modified humic ligand of the Fe-HA complex. Their accumu- lation provided an explanation for the enhancement of Zn binding by P-treated soil. In addition to P=O bonds, the C=C bonds should also be considered as functional groups capable of metal ion bin- ding. Because of the greater number of electron-donor groups in the pyro-P-modified humus ligand, the pyro-P-treated soil bound Zn more firmly than the ortho-P-treated one. The dissimilar struc- ture of the control and ortho-, pyro-P-modified humus ligands had a direct relationship with the capability of microflora to adapt to the rising Zn pollution of soil. As compared with control, toxic action of Zn compounds was even enhanced by ortho-P although its addition to soil promoted the Zn binding. On the contrary, pyro-P addition to soil reduced the toxic action of Zn compounds. Con- sequently, the capability of soil to bind external Zn into inert and nontoxic compounds depends on the structural features of humus ligands in surface metal-humus complexes which are of a great importance as sorption barriers.
słowa kluczowe humus ligand structure, phosphate fertilizers, zinc binding