The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM 10 active samplers and passive PUF disk samplers in Tangshan City,a metropolis containing clusters of various industrial plants.The ΣTEQ concentrations of ΣPCDD/ΣPCDFs ranged from 44.2 to 394.1 fg I-TEQ/m 3 with an average of 169.9 fg I-TEQ/m 3.2,3,4,7,8-PeCDF was the dominant contributor to TEQ,contributing 41% (12% to 55%),while 1,2,3,4,6,7,8-HpCDF,OCDD and OCDF were the major congeners for the total concentrations.The ratios of PCDF/PCDD reached 2.54 on average,suggesting that de novo synthesis in thermal processes played an important role to the airborne pollution of PCDD/PCDFs.The similarities congener profiles indicated that TSP and PM 10 active sampling methods are comparable for the determination of the PCDD/PCDFs in ambient air,and the ratios of concentrations determined by the two methods suggested that the PCDD/PCDFs tended to stay in fine particles.It was found that 2,3,7,8-TCDF and OCDD were the dominating congeners in the passive PUF disks samples.Through principal components analysis,the coke industry was suggested to be a relatively high potential emission source for PCDD/PCDFs in the ambient air of Tangshan,which was possibly formed by de novo synthesis mechanism.In this study,the atmospheric impacts to the environment from different industrial sources could be ranked as follows (from high to low):coking,iron sintering,steel making,power generation and chlorinate alkali chemical production industries.
Zhiyuan Ren Bing Zhang Pu Lu Cheng Li Lirong Gao Minghui Zheng
