| Dioxins are a pernicious and persistent organic pollutants, dioxins in the atmosphere can spread quickly through atmospheric transport, sources of emissions of dioxins can transfer to migrate to various units within the region and even worldwide distribution, and through exchange between the atmosphere and water bodies, soil and plants into the human food chain.Therefore, the importance of regional atmospheric environment of dioxin pollution status monitoring and environmental impact assessment studies.In this research, seventeen kinds of atmospheric PCDD/Fs components sampling from6regions of Guangzhou City in autumn were determined using GC/HRMS. The results demonstrated that the toxic equivalent (TEQ) of PCDD/Fs were in the range of0.151to2.23pg I-TEQ/m3and an average value was0.419pg I-TEQ/m3.Moreover, the levels of atmospheric PCDD/Fs components were associated with regional environment. The results verified that the lower and similar TEQ of PCDD/Fs were0.294,0.305and0.308pg I-TEQ/m3in the background, residential and commercial areas, respectively. Meanwhile, the TEQ levels in transport hub area, suburban and industrial areas were higher with the values as0.342,0.423and0.838pg I-TEQ/m3, separately.Furthermore, TEQ distribution trend in functional urban regions of Guangzhou City ranked as background<residential<commercial district<transport hub area<suburban<industrial district. Additionally, compared with that of2004, the average TEQ in2011decreased in urban area and increased in suburban area.The congener profile of atmospheric PCDD/Fs in Guangzhou was steady. The concentrations of OCDD is the highest, which accounting for a range of23%～50%to total concentration, followed by OCDF (16%-36%) and HpCDFs (18%～28%).However, the total PCDD/Fs compounds the situation is somewhat different, the most dominant homologues in turn is TCDF, OCDD, PeCDFs and HpCDFs. The major sources of emissions of the regional and regional function, while a direct impact on the distribution characteristics of each region of the dioxin homologues.The PCDD/Fs concentration range with gas phase in atmosphere of Guangzhou is0.262pg/m3-10.8pg/m3, the particle phase of PCDD/Fs concentration range is7.91pg/m3-23.0pg/m3. Monomer concentration of the contribution rate, except for background,2,3,7,8-TCDF in the vapor contribution to the highest rate of the particle phase1,2,3,4,6,7,8-HpCDF, OCDF and the highest OCDD concentration, three on the contribution of the total concentration greater than75%.PCDD/Fs in Volatile different monomer form of the distribution in the gas phase and particle phase is not the same, the lower chlorinated PCDD/Fs are mostly distributed in the gas phase, the higher chlorinated PCDD/Fs are mainly distributed in the particle phase, while and PCDFs and PCDDs. become more distributed in the particle phase may be due to PCDDs vapor pressure is low. Guangzhou City of dioxins in the atmosphere gas-solid allocation and Beijing, Japan and in other cities or regions.Of human daily intake in six districts in Guangzhou,the daily intake for adult was3.43pg I-TEQ/kg/day, the daily intake for children was6.09pg I-TEQ/kg/day.The highest rough inhalation risk appeared in Industrial area. The rough inhalation risk of the industrial zone of adult18.0×102pg I-TEQ/kg/day, children31.8×10-2pg I-TEQ/kg/day. The lowest rough inhalation risk appeared in background. The rough inhalation risk of the background of adult6.30×10-2pg I-TEQ/kg/day, children11.2×10-2pg I-TEQ/kg/day. The source analysis showed that the dioxin emission sources of urban atmospheric environment is more complex, non-single source of emissions. And there are significant regional differences in the surrounding environment can also affect the level of dioxin pollution in the region. Generally speaking, the urban atmospheric dioxin main source of waste incineration, transport and industrial emission sources. |
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