Pedosphere 6(3): 201--208, 1996
ISSN 1002-0160/CN 32-1315/P
©1996 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Acid dissociation constants of functional groups in humic substances: Ⅰ. Affinity spectrum model analysis of potentiometric data of fulvic and humic acids solutions from weathered coal and dark loessial soil |
| DU Jin-Zhou1, CHANG Zheng1, ZHANG Zi-Ping1, TAO Zu-Yi1 and LU Chang-Qing2 |
1 Department of Modern Physics, Lanzhou University, Lanzhou 730000 (China)
2 Institute of Soil Science, Academia Sinica, P.O.Box 821, Nanjing 210008 (China) |
| ABSTRACT |
| Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and FA extracted from a dark loessial soil. The affinity spectrum model was employed to treat the experimental data. The affinity spectrum model technique could "magnify" the heterogeneity of the proton binding equilibria, so it was useful for comparing and studying the characteristics of humic substances with similar properties. According to the affinity spectra, we also found that the direction of the titration could affect the properties of the equilibria of FA from the weathered coal, and the acidic functional groups contained in FA from the weathered coal were larger in quantity than those contained in HA and FA from the dark loessial soil. |
| Key Words: affinity spectrum, heterogeneity, humic substances, potentiometric titration |
| Citation: Du, J. Z., Chang, Z., Zhang, Z. P., Tao, Z. Y. and Lu, C. Q. 1996. Acid dissociation constants of functional groups in humic substances: Ⅰ. Affinity spectrum model analysis of potentiometric data of fulvic and humic acids solutions from weathered coal and dark loessial soil. Pedosphere. 6(3): 201-208. |
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