title: Precursors of dichloroacetamide, an emerging nitrogenous DBP formed during chlorination or chloramination.
abstract: Haloacetamides (HAcAms) are an emerging class of nitrogenous disinfection byproducts (N-DBPs). However, there is a limited understanding about the precursors of HAcAms. In this study, we screened the precursors of dichloroacetamide (DCAcAm), the most commonly identified HAcAm in chlorinated or chloraminated drinking water. DCAcAm formation potential (FP) of raw water samples collected in different months from a reservoir in China was determined during chlorination, and the highest DCAcAm FP typically occurred in the summer samples. Dissolved organic matter (DOM) in a representative summer raw water sample was separated into six fractions by a series of resin elutions. Among them, hydrophilic acid (HiA) DOM showed the maximum DCAcAm FP, followed by hydrophilic bases (HiB) and, to a much lower extent, hydrophobic acids (HoA). Fluorescence excitation-emission matrix (EEM) spectra revealed that a mass of protein-like substances in the HiA fraction, made up of amino acids (AAs), were the likely DCAcAm precursors. Finally, we investigated the DCAcAm yields of 20 AAs during chlorination. Among them, seven AAs (aspartic acid, histidine, tyrosine, tryptophan, glutamine, asparagine, phenylalanine) could form DCAcAm during chlorination, with the corresponding DCAcAm yields of 0.231, 0.189, 0.153, 0.104, 0.078, 0.058, and 0.050 mmol/mol AA.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
authors.forename: Wen-Hai
authors.initials: WH
authors.lastname: Chu
authors.forename: Nai-Yun
authors.initials: NY
authors.lastname: Gao
authors.forename: Yang
authors.initials: Y
authors.lastname: Deng
authors.forename: Stuart W
authors.initials: SW
authors.lastname: Krasner
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*
chemical_list: D000081:Acetamides; D004202:Disinfectants; D002713:Chlorine; C032619:2,2-dichloroacetamide; D009584:Nitrogen