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Proceedings Paper

Degradation of humic acids by UV-radiation and ozone
Author(s): J. Chmura; Zbigniew Gorski; P. Grobelny; Janusz Slawinski
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Paper Abstract

Model research was performed on the influence of UV- radiation and ozone on humus substances (HS) - dark ubiquitous biopolymers, the most important component of soil and aquatic organic matter. Aqueous aerated solutions of natural and synthetic model HS (0.001-0.08%) were irradiated with UV - and visible radiation in a flow-circulation system or exposed to the atmosphere containing 0.027 ppm ozone. Control and tested samples were analyzed using the chemiluminescence (CL) method, UV and Vis spectrophotometry and EPR spectroscopy. The results obtained indicate that dry HS are resistant to the UV- and visible radiation and low concentrations of ozone. However, HS is aerated solutions undergo degradative oxidation. These exergonic reactions are accompanied by the generation of electronically excited states and free radicals that manifest as a CL and changes in EPR signals. Prolonged irradiation or exposure to ozone causes a gradual degradation of the aromatic core of HS to hydrophilic, low molecular carboxylic products. Mechanisms of the degradation reactions, CL, changes in EPR signals and optical density of HS are proposed and possible ecological consequences of these processes are considered.

Paper Details

Date Published: 11 July 2001
PDF: 10 pages
Proc. SPIE 4515, Light and Optics in Biomedicine, (11 July 2001); doi: 10.1117/12.432988
Show Author Affiliations
J. Chmura, Pedagogical Univ. (Poland)
Zbigniew Gorski, Poznan Univ. of Technology (Poland)
P. Grobelny, Poznan Univ. of Technology (Poland)
Janusz Slawinski, Poznan Univ. of Technology (Poland)

Published in SPIE Proceedings Vol. 4515:
Light and Optics in Biomedicine
Maksymilian Pluta; Anna Cysewska-Sobusiak, Editor(s)

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