Seasonal occurrence of N-nitrosamines and their association with dissolved organic matter in full-scale drinking water systems: Determination by LC-MS and EEM-PARAFAC.

N -nitrosamines have been identified as emerging contaminants with tremendous carcinogenic potential for human beings. This study examined the seasonal changes in the occurrence of N -nitrosamines and N -nitrosodimethylamine formation potential (NDMA-FP) in drinking water resources and potable water from 10 drinking water treatment plants in a southern city of China. The changes in N -nitrosamines are well correlated with dissolved organic matter (DOM), particularly fluorophores, which were measured and compared between traditional fluorescence indices and excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Four of N -nitrosamine species including N -nitrosodimethylamine (NDMA), N -Nitrosodibutylamine (NDBA), N -Nitrosopyrrolidine (NPYR), and N -Nitrosodiphenylamine (NDPhA) are found to be abundant compounds with an average of 29.5% (26.7%), 20.0% (25.2%), 18.9% (16.0%), and 9.0% (9.9%) in the source (and treated) water, respectively. The sum of N -nitrosamines concentration is recorded to be low in the wet season (July–September), whereas the dry season (October–December) provided opposite impacts. EEM-PARAFAC modeling indicated the predominance of humic-like component (C1) in the wet season while in the dry season the water was dominant in protein-like component (C2). All the N -nitrosamines excluding NDPhA and N -Nitrosomorpholine (NMOR) showed a strong association with protein-like component (C2). In contrast, humic-like C1, which was directly influenced by rainfall, was found to be a suitable proxy for NMOR and NDPhA. The results of this study are valuable to understand the correlation between different N -nitrosamines and DOM through adopting fluorescence signatures. Image 1 • The mean concentration of each N -nitrosamine in drinking water is below 5 ng/L. • Sum of N -nitrosamines in drinking water is higher in dry season than wet season. • Humic-like component shows higher intensity in wet season. • Most of N -nitrosamines associate with protein-like component. • Compare to HIX and BIX, EEM-PARAFAC provides better proxies for N -nitrosamines. [ABSTRACT FROM AUTHOR]