Analytical Sciences

Determination and Behavior of Humic Substances as Precursors of Trihalomethane in Environmental Water

Etsu YAMADA* , **, Takashi OZAKI* and Machiko KIMURA*

*Department of Chemistry and Material Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606, Japan
**Center for Environmental Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606, Japan

Humic and fulvic acids in environmental water were determined by UV spectrophotometry after concentration withdiethylaminoethyl(DEAE)-cellulose and separation at pH 1 by centrifugation. The ranges of fulvic and humic acids in Katsura, Uji, Kidzu and Yodo Rivers were from about 0.50 to 3.2 mg/l and 0.025 to 0.2 mg/l, except for the sampling points, which were located downstream of a sewage-disposal plant. Fulvic acid was predominant in these rivers. The concentrations of humic substances were high in the summer and low in the winter. The concentrations of humic sub-stances in these rivers decreased fairly much from December of 1992 to August of 1993. The annual changes in the val-ues of humic substances during 1993 to 1996 were smaller than the change from 1992 to 1993. The trends for the season-al and annual changes in the concentration of the trihalomethane formation potential in Yodo rivers were almost consis-tent with those of humic substances. (Keywords: Humic acid, fulvic acid, environmental water, seasonal change, annual change, trihalomethane formation)

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