Dynamics and chemical nature of fluorescent dissolved organic matter in river waters in Hiroshima Prefecture, Japan

Abstract

Dynamics and chemical nature of fluorescent dissolved organic matter (FDOM) were investigated in two river waters. DOC monthly and temporarily varied in the two river waters. The FDOM in the river waters identified three characteristic fluorescence peaks, indicating the occurrence of fulvic acids (peak F), fluorescent whitening agents (peak W), and protein-like substances (peak T). The FDOM in upstream and Ohta downstream contained the peaks F and T whereas Kurose downstream waters contained the peaks W and T. The ratio of fluorescence intensity for peak F or W with DOC (FI/DOC-index), diurnal variations and photo irradiation experiments for FDOM indicated that the chemical properties of FDOM in the Kurose downstream are different with those in the Kurose upstream and Ohta river waters.