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A field study and theoretical calculations were performed to clarify the levels,profiles,and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in a cement kiln co-processing solid waste,with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln.The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln.The PBDD/F concentrations in the clinkers were 1.40％ of the concentrations in the raw materials,which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln.PBDD/F distribution patts in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation.PBDFs with high levels of halogenation,such as heptabrominated furans (HpBDF),were the dominant contributors to the total PBDD/F concentrations and accounted for 42％-73％ of the total PBDD/F concentrations in the particle samples.Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs,especially for the higher halogenated PBDD fraction.In addition,there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations,which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs.Theoretical calculations were performed and demonstrated that elimination of HBr and Br2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs.These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs).