Influence of UV irradiation on the toxicity of chlorinated water to mammalian cells: Toxicity drivers, toxicity changes and toxicity surrogates

摘要

UV irradiation was reported to be able to degrade some kinds of DBPs, yet its influence on the toxicity of chlorinated water to mammalian cells remains unknown. This study systematically investigated the influence of low-pressure UV irradiation on the DBPs and toxicity of chlorinated drinking water (DW) and reclaimed water (RW). The apparent first-order rate constant (k(obs)) of degradation kinetics of known DBPs increased with the increased Br substitutions. Haloacetonitriles were identified as toxicity drivers among the detected DBPs, which even contributed more to the toxicity after UV irradiation, mainly due to the refractory bromochloroacetonitrile (BCAN) and dichloroacetonitrile (dCAN). Both total organic halogen, cytotoxicity and genotoxicity were significantly removed under UV irradiation, with the removal rate of 22.9%-41.7% for cytotoxicity and a higher rate of 33.1%-55.5% for genotoxicity under 2400 mJ/cm(2) irradiation. UV irradiation significantly decreased the UV254. SUVA(254) and fluorescence intensity (FLU) of chlorinated water. Results from high performance size exclusion chromatography revealed that chlorinated DW mainly contained high molecular weight (MW) compounds (>1000 Da) while chlorinated RW mainly contained lower MW compounds (100-500 Da). Chromophores and fluorophores in compounds of 100-500 Da increased in chlorinated DW while decreased in chlorinated RW under UV irradiation. Both the removal of UV254, SUVA(254), FLU, MW-based UV254 (>1000 Da) and MW-based FLU (each fractions) were significantly correlated (p < 0.05) with the removal of toxicity under UV irradiation. The UV254 of chlorinated water was recommended as the optimal surrogate for toxicity removal. (C) 2019 Elsevier Ltd. All rights reserved.