Abstract
Three-dimensional excitation-emission matrix (EEM) fluorescence spectra were used to evaluate and compare the characteristics of dissolved organic matter (DOM) in lake and river waters as well as effluent from several sewage treatment plants. Our comparisons of the EEMs indicated a substantial difference in the peak profiles among the samples. For example, five peaks (i.e. Ex/Em = 225/280, Ex/Em = 225/340, Ex/Em = 240/420, Ex/Em = 340/430, and Ex/Em = 480/520nm) were observed on the EEM of the sewage treatment plant effluent, but only two peaks (i.e. Ex/Em = 240/420 and Ex/Em = 340/430nm) were observed in the case of the lake and river waters. Furthermore, one of the peaks (i.e. Ex/Em = 340/430), which has been used as an indicator of the humic-like groups of DOM, was actually found in the EEMs of both humic and non-humic fractions prepared by the XAD-8 resin fractionation method. The non-humic fraction consistently accounted for 30-50% of the peak intensity of the DOM . This result suggests that the peak at Ex/Em = 340/430 is not appropriate as an indicator of humic-like groups in DOM.
