Total luminescence spectroscopy of NOM-typing samples and their aluminium complexes

Samples from the Scandinavian NOM-typing set were studied by total luminesc ence spectroscopy (TLS). All samples showed fluorescence spectra typical fo r NOM of aquatic origin, or fulvic acids from both aquatic and terrestrial sources, but were lacking additional features typical for humic acid and le af litter extract spectra. A comparison of the NOM spectra from the same so urce, but isolated by different methods, suggests that the reversed osmosis isolation procedure removes a small percentage of all fluorescing compound s when compared to the evaporation procedure. Spectral differences between NOM samples of different age suggest reduction of the more highly conjugate d aromatics with increasing residence time in the water either by precipita tion or by biodegradation to simple phenolics. NOM samples were spiked with aluminium, which led to pronounced qualitative changes in the NOM TLS. The most prominent change was the appearance of a shoulder at lambda(ex)/lambd a(em) = 350/375. The fluorescence intensity at this wavelength pair was fou nd to be positively correlated with inert and "bound" Al, as determined by fast reaction with 8-hydroxyquinoline and capillary electrophoresis, respec tively. (C) 1999 Elsevier Science Ltd.