Abstract
In Lake Biwa, an increase of refractory dissolved organic matter (DOM) has been a problem since 1985. The main origin of this material may be soil humic substances and algal DOM. The fractionation of hydrophobic acids (humic substances) with DAX-8 resin is time consuming and cannot be applied to water samples whose DOC concentrations are low. Thus, a simple analysis of humic substances in water samples using a three-dimensional excitation emission matrix (3-DEEM) and DOC was investigated. This was compared with fractionation analysis, and applied to the dynamics of humic substances in Lake Biwa and its surrounding rivers. The results of humic substances in Yodo rivers by simple analysis using soil fulvic acid (Dando FA) as a standard were in relatively good agreement with those by the fractionation analysis, except for Uji River, where the water of Lake Biwa have an affect through Seta River. This simple analysis was also applied to the dynamics of humic substances in the rivers flowing into Lake Biwa. In the case of a simple analysis of humic substances in Lake Biwa, Biwako FA was used as a standard instead of Dando FA.
