Long-term ozone consumption by aquatic fulvic acids acting as precursors of radical chain reactions

Abstract

A preozonated commercial humic acid has been reported to undergo radical chain reactions with ozone. This study reports the ozone consumption by a number of aquatic fulvic acids. In the presence of OH-radical scavengers, it was found that the relative ozone consumption increased as the initial ozone dose, pH, and relative UV absorbance of fulvic acids increased. This consumption became greater, however, in the absence of scavengers, demonstrating undoubtedly the occurrence of radical chain reactions between the fulvic acids and ozone. The intermediate fulvic acid ozonation products, namely, hydrogen peroxide and glyoxalic acid, were also identified as precursors of radical chain reactions