Fluorimetric tracing of sewage effluents in the Murinsky creek
The Murinsky creek starts in a city park and takes waters from several canalization outlets of Saint-Petersburg on its way. Fluorimetric properties and chemical parameters (electric conductivity, pH, content of total organic carbon (TOC) and total nitrogen (TN)) of the creek water samples were analyzed in order to reveal the most informative parameters for express determination of water pollution sources. The obtained results showed that electric conductivity and TOC content do not allow distinguishing between unpolluted (natural) and polluted water samples due toseasonal variation of natural background values. Fluorimetric properties at excitation wavelength 230 nm such as intensity of tyrosine-like fluorescence at 300 nm and tryptophan-like fluorescence at 340 nm proved to be informative for sewage effluents tracing in the Murinsky creek. Ratio of tyrosine-like (ex230 em300) to humic-like (ex230 em420) fluorescence for unpolluted waters was 0,06...0,27, for polluted waters –0,25...0,81. Ratio of tryptophan-like (ex230 em340) to humic-like (ex230 em420) fluorescence for not polluted waters was within 0,14...0,94 and for polluted waters –0,72...2,85. Significant increasing of one or both ratios was observed in waters after sewage outlets. Ratio of tyrosine-like to humic-like fluorescence showed high correlation with TN (r = 0.98), and TN/TOC (r = 0.96).