Ozone-induced changes in natural organic matter (NOM) structure

Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sou rces and two US river systems with terrestrial organic carbon sources, were ozonated. Several analyses, including C-13-NMR, UV absorbance, fluorescenc e, hydrophobic/transphilic classification, and potentiometric titrations, w ere performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the sa mples resulted in increased aliphatic, carboxyl, plus acetal and ketal anom eric carbon content and shifted towards less hydrophobic compounds.