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

• Published in: Water research (Oxford) 2020-09, Vol.183, p.116096, Article 116096
• Main Authors: Maqbool, Tahir, Zhang, Jiaxing, Qin, Yanling, Ly, Quang Viet, Asif, Muhammad Bilal, Zhang, Xihui, Zhang, Zhenghua
• Format: Article
• Language: English
• Subjects: Dissolved organic matter; EEM-PARAFAC; Fluorescence spectroscopy; Full-scale drinking water systems; N-nitrosamines
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2020.116096

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. [Display omitted] •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.