Characterization of organic matter by HRMS in surface waters: Effects of chlorination on molecular fingerprints and correlation with DBP formation potential

• Published in: Water research (Oxford) Vol. 176; p. 115743
• Main Authors: Sanchís, Josep, Jaén-Gil, Adrián, Gago-Ferrero, Pablo, Munthali, Elias, Farré, Maria José
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-06-2020
• Subjects: DBP formation Potential; Disinfectants; Disinfection; Disinfection by-products; Dissolved organic matter; Halogenation; High resolution mass spectrometry; Mass Spectrometry; Trihalomethanes; van krevelen diagram; Water chlorination; Water Pollutants, Chemical; Water Purification; High resolution mass spectrometry; Disinfection by-products; van krevelen diagram; Dissolved organic matter; DBP formation Potential; Water chlorination
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2020.115743

In order to understand and minimize the formation of halogenated disinfection by-products (DBPs), it is important to investigate how dissolved organic matter (DOM) contributes to their generation. In the present study, we analysed the DOM profile of water samples from the Barcelona catchment area by high resolution mass spectrometry (HRMS) and we studied the changes after chlorination. Chlorination produced significant changes in the DOM, decreased the average m/z and Kendrick mass defect (KMD) of their spectra and decreased the number and abundance of lignin-like features. The Van Krevelen (VK) fingerprint exhibited several noticeable changes, including the appearance of highly oxidized peaks in the tannin-like region (average O/C, 0.78 ± 0.08), the appearance of features with low H/C and the disappearance of more than half of the lipids-like features. Up to 657 halogenated peaks were generated during sample chlorination, most of which in the condensed hydrocarbons-like and the lignin-like region of the VK diagram.
Around 200 features were found to be strongly correlated (ρ ≥ 0.795) to the formation potential of trihalomethanes (THMs) and 5 were correlated with the formation potential of haloacetonitrile (HANs). They all were plotted in the lignin fraction of the VK diagram, but both groups of features exhibited different nitrogen content: those features related to HANs FP had at least one nitrogen atoms in their structures, whilst those related to THMs did not.
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•>650 halogenated features were generated during sample chlorination.•Water chlorination decreased the number and abundance of lignin-like features.•Most halogenated DBPs appeared in the lignin- and condensed hydrocarbon-like regions.•Certain N-containing lignin-like features correlate with the formation of HAN.•Certain lignin-like features with no nitrogen correlate with the formation of THMs.