Changes in NOM fluorescence caused by chlorination and their associations with disinfection by-products formation.

Relationships between the formation of disinfection byproduct (DBPs) and changes of the fluorescence of natural organic matter (NOM) in chlorinated water were quantified using two fluorescence indexes. They were defined as the change of the wavelength that corresponds to 50% of the maximum intensity of fluorescence (Deltalambdaem0.5) and the differential ratio of fluorescence intensities measured at 500 and 450 nm (Delta(I500/I450)). Although variations of chlorine doses, reaction times and temperatures affected the kinetics of chlorine consumption and DBPs release, correlations between chlorine consumption, concentrations, and speciation of trihalomethanes, haloacetonitriles, haloacetic acids and, on the other hand, Delta(I500/I450) and Deltalambdaem0.5 values remained unaffected by chlorination conditions and, to some extent, NOM properties. These results allow developing a fluorescence-based approach to monitor DBPs formation in drinking water.