The concentrations of DBPs in the small systems under study vary
according to the seasons (Fig. 2b and c). Fig. 2 indicates that DBP levels
are clearly higher in NL than in QC. Summer and fall show significantly
higher levels of DBPs than the other seasons. This is due partly to the
variableamount of available organic matter, themost important precursor
of DBPs (Chen et al., 2008).