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From Molecular Understanding to Innovative ... - Humus.ru

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a degree of humification. It is noteworthy that results obtained from ultrasonic<br />

measurement, which is based on completely different principle, are in compliance with<br />

optical methods.<br />

Furthermore, ultrasound velocity was measured at 8 different frequencies and at all<br />

frequencies did not differ, which implies that although humic molecules aggregate, the<br />

compressibility of resulted organizations do not decrease the ultrasonic velocity. Ultrasonic<br />

waving is mechanical in nature and causes compression and decompression of present<br />

aggregates. Therefore if no decrease in ultrasonic velocity was observed, formation of<br />

spherical, i.e. highly compressible micelles, or micelle-like aggregates can be excluded.<br />

4. CONCLUSIONS<br />

High resolution ultrasonic spectroscopy can be used <strong>to</strong> study assembling mechanism<br />

of several systems including humic substances solutions. Sodium salts of humic and fulvic<br />

acids self-aggregate from low concentrations but form only small associates and no<br />

micelle-like st<strong>ru</strong>ctures occur.<br />

ACKNOWLEDGEMENTS<br />

The financial support of Ministry of Education of the Czech Republic, project MSM<br />

0021630501 and Grant Agency project number GA 104/08/0990 are acknowledged.<br />

REFERENCES<br />

1. Vaughan, D., 1967. Effect of humic acid on the development of invertase activity in slices of<br />

beetroot tissues washed under aseptic conditions. <strong>Humus</strong> et Planta IV, pp. 268-271.<br />

2. Ladd, J.M., Butler, J.H.A., 1971. Inhibition and stimulation of proteolytic enzyme activities by<br />

soil humic acids. Australian Journal of Soil Research 7, pp. 253-261.<br />

3. Wershaw, R.L., 1986. A new model for humic materials and their interactions with hydrophobic<br />

chemicals in soil–water and sediment–water systems. Journal of Contaminant Hydrology 1,<br />

pp. 29-45.<br />

4. Kučerík, J., Šmejkalová, D., Čechlovská, H., Pekař, M., 2007. New insights in<strong>to</strong> aggregation<br />

and conformational behaviour of humic substances: Application of high resolution ultrasonic<br />

spectroscopy. Organic Geochemistry 38, pp.2098-2110.<br />

5. Engebretson, R.R., von Wand<strong>ru</strong>szka, R., 1994. Microorganization of dissolved humic acids.<br />

Environmental Science and Technology 28, pp. 1934-1941.<br />

6. Kankia, B.I., Funck, T., Uedaira, H., Buckin, V., 1997. Volume and compressibility effects in<br />

the formation of metal-EDTA complexes. Journal of Solution Chemistry 26, pp. 877-888.<br />

7. Buckin, V., Kudryashov, E., Morrissey, S., Kapustina, T., Dawson, K., 1998. Do surfactants<br />

form micelles on the surface of DNA? Progress in Colloid Polymer Science 110, pp. 214-219.<br />

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