UV/chlorine and chlorination of effluent organic matter fractions: Tracing nitrogenous DBPs using FT-ICR mass spectrometry

•UV/Cl2 generated more diverse N-DBPs with higher intensity than chlorination.•UV/Cl2 led to more hydrophilic, less aromatic, higher Cl-incorporating DBPs than chlorination.•TPI EfOM formed more specific N-DBPs than HPO fraction by both UV/Cl2 and chlorination.•DBPs with significant rank correlation with cell DNA damage were identified.•UV/Cl2 reduced the cytotoxicity but enhanced oxidative stress-induced DNA damage.