Detection of domestic wastes in Kurose river using synchronous fluorescence spectroscopy

This study was conducted to determine the applicability of synchronous fluorescence spectroscopy (SFS) in differentiating natural organic matter (NOM) from dissolved organic matter (DOM) derived from domestic wastes and in detecting their presence in Kurose River. Sewage effluent, gray water, water extracts from leaf mold and top soil, respectively, algal culture media, and water samples from different points of the river were analyzed. A laboratory mixing experiment was conducted by combining the leaf mold water extract (LM-NOM) and sewage effluent at different ratios. The SFS of the samples were run at offset value of Δλ=40 nm (Δλ=λem−λex). The corrected synchronous fluorescence spectra of LM-NOM and the sewage effluent showed different spectral features. A very intense peak at about 531 nm was observed in the sewage effluent spectrum which was not found in the LM-NOM sample. The mixing of fluorescing organic material in LM-NOM and sewage effluent resulted in the simple addition of their respective spectra. This allows the detection of pollutants in surface waters by the appearance of characteristic peaks of the added wastewater. The corrected spectra of the river water sample from a relatively unpolluted point of Kurose River exhibited a simple spectrum with a single peak while the spectra of those collected downstream showed peaks similar to those found in the sewage effluent and gray water spectra. These results demonstrate the applicability of SFS in detecting the presence of different DOM in surface waters.