Quaternary ammonium compounds (QACs) have raised considerable attention due to their wide commercial applications and recent discovery of unknown persistent analogues in aqueous environment. In this work, the occurrence and distribution of alkyltrimethylammonium (ATMAC), benzylakyldimethylethylammonium (BAC) and dialkyldimethylammonium (DADMAC) homologues were investigated in fifty-two municipal sewage sludge samples. ATMAC C10−18, BAC C8−18 and paired DADMAC C8:8-C18:18 as well as emerging homologues such as 18:20 were identified for the first time by nontarget qualitative strategies. A triple quadruple mass spectrometer quantification method was also initially verified with the aid of laboratory synthesized standards for the analysis of the mixed DADMACs with no certificated commercial standards currently available. The total concentrations of ATMACs, BACs and DADMACs were in the range of 0.38−293, 0.09−191 and 0.64−344 μg/g dry weight, respectively, and particularly, mixed DADMACs constituted 39 ± 7% of total DADMAC concentrations. The concentrations and profiles of individual homologues further suggested different QAC applications and fate in China. Significant correlations were also found among the concentrations of various QAC homologues as well as wastewater treatment plant (WWTP) characteristics (total organic carbon contents and daily treatment volumes). ■ INTRODUCTIONRapid development of analytical methods and increasing public health concerns have improved the assessment and regulatory strategies for screening chemicals with persistent, bioaccumulative, and toxic potentials, especially from the high production volume chemical (HPVC) list. 1−5 Surfactants are an economically important class of HPVCs, with wide consumer usages and industrial applications. The transport, fate, and possible adverse effects of some important neutral and anion surfactants, such as nonylphenolethoxylates and relevant metabolites, have been extensively investigated in various environmental compartments. 6,7 However, less attention has been raised on cationic surfactants, although some of these could be environmentally persistent as they result from the amphiphilic and electrostatic interactions with negatively charged surfaces and are potentially toxic to aquatic organisms. 8−12 Here, we focused our research on quaternary ammonium compounds (QACs), a class of cationic surfactants that are commonly used as detergents, phase transfer catalysts, fabric softeners, disinfectants as well as preservatives and antielectrostatics in personal care products. 8,13 QACs mainly consist of the alkyltrimethylammonium (ATMACs), benzylalkyldimethylethylammonium (BACs), and dialkyldimethyl-ammonium compounds (DADMACs) as shown in Figure 1. The analysis and ecological risk assessment of QACs in the environment began in the 1980s. QAC residues have been found in surface water, 14 sewage effluent, 15,16 estuarine sediment, 9,13,17−19 sludge, 13,20,21 Received: November 12, 2013

Extensive use of bisphenol A and its analogues has caused increasing concern over the potential adverse health impacts of these chemicals. In this study, the presence and profiles of 13 bisphenols (BPs) were investigated in 52 municipal sewage sludge samples collected from 30 cities in China. Tetrabromobisphenol A was the most frequently observed analogue (geometric mean: 20.5 ng/g dw). Bisphenol A (4.69 ng/g dw), bisphenol S (3.02 ng/g dw), and bisphenol F (3.84 ng/g dw) were found with similar frequency. Other BP analogues such as tetrachlorobisphenol A, bisphenol AF, bisphenol E, and dihydroxybiphenyl were identified for the first time in sewage sludge in China. Significant correlations were found among BP concentrations, but no relationships were found with wastewater treatment plant characteristics. Profiles of the relative estradiol equivalents suggested that the estrogenic potential of BP mixtures may be associated with the occurrence and contributions of specific analogues.

Synthetic phenolic antioxidants (SPAs) are one group of widely used additive chemicals, which have not yet had focused attention except for a few compounds such as 2,6-di-tert-butyl-4-methylphenol (BHT). In this study, the occurrence and composition profiles of 12 frequently used SPAs and three BHT metabolites were investigated in fifty-six sludge samples collected from individual wastewater treatment plants in China. Eleven SPAs were positively found in the sludge samples, in which, to our knowledge, eight SPA compounds were identified for the first time in the environment. BHT, 4-tert-octylphenol (4-tOP), and 2,4,6-tri-tert-bultylphenol (AO 246) were the most dominant SPAs in the sludge at mean concentrations of 4.14 μg/g, 374 ng/g, and 98.1 ng/g d.w. (dry weight). Meanwhile, three BHT metabolites, including 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO), 2,6-di-tert-butyl-1,4-benzoquinone (BHT-Q), and 2,6-di-tert-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-quinol), were also found in most of the samples (>98.2%) with mean concentrations of 141, 562, and 225 ng/g d.w., respectively. The activated sludge system (anaerobic, anoxic, and oxic tanks) of a wastewater treatment plant was further investigated for the removal efficiencies of the SPAs. High removal efficiencies (80.1−89.2%) were found for the six detected SPAs in the aqueous phase, while generation of large proportions of the three BHT metabolites was also observed.