Levels and distributions of polychlorinated naphthalenes in sewage sludge of urban wastewater treatment plants

Over seventy congeners of polychlorinated naphthalenes(PCNs) in sewage sludge of 8 urban waste-water treatment plants(WWTPs) in Beijing were analyzed by isotope dilution,and high resolution gas chromatography/high resolution mass spectrometry(HRGC/HRMS) method.The total PCN concentrations determined in the samples range from 1.48 to 28.21 ng/g dw(dry weight) with TEQ concentrations of 0.11―2.45 pg/g dw.These levels were lower than those found in other regions.DiCNs and TrCNs were the most dominant homologues of PCNs.The similar congener profiles in all the samples suggest the similarity in certain sources.Contamination from industrial input might be the most significant source of PCNs in the sludges in this study,and thermal processes such as waste incineration and coal combustion may be another source of the PCNs contamination.