Insights into the molecular compositions of CX3R-type disinfection byproduct precursors in algal organic matter from algae-laden water

The precursors of commonly known DBPs have been widely investigated, yet few studies have paid attention to the typical compositions of AOM-related DBP precursors at molecular-level. Hence, in this study, we established the potential relationships by linking AOM molecular formulas or properties with the formation potentials of typical CX3R-type DBPs (i.e., dichloroacetonitrile (DCAN), trichloroacetone (TCP) and trichloromethane (TCM)) by regression analysis and Spearman's correlation analysis. By the results of significant and strong correlations between AOM molecules and DBP formation potentials, the typical precursors of DCAN or TCP were observed to be the molecules with relatively high O/C (0.5-0.8) and low H/C (0.9-1.8) ratios, while different precursors of TCM were obviously determined. Compared to the aliphatic and vascular plant-derived polyphenol compounds, the phenolic and highly unsaturated aliphatic compositions were prone to generate DCAN and TCP in chlorination. Besides, the H/N and O/N ratios of precursors of DCAN distributed around a straight line, namely, H/N = 1.86 O/N + 1.23. Such findings will provide new insights into the specific precursors at molecular-level and be beneficial to the development of effective controlling strategies for these AOM-related DBPs.