| With the rapid development of today’s social informatization, the electronic product’s replacement rate is accelerating, so hundreds of million of tons of electronic products have been eliminated every year. In China, large amounts of waste electronic equipments in their own country, in addition there are a lot of electronic waste were imported into this country. E-waste are rich in large amounts of resources, so the e-waste dismantling contains huge business opportunities, but it will release a lot of toxic and hazardous pollutants if dismantling unproperly. Among these pollutants, Polychlorinated dibenzo-p-dioxins/furans(PCDD/Fs) and polybrominated dibenzo-p-dioxins/furans(PBDD/Fs) are two typical refractory organic pollutants. PCDD/Fs and PBDD/Fs are two kinds of halogenated aromatic pollutants with similar structure and characteristics, and are persistent, bioaccumulative and highly toxic in the environment. Widely concerned by various countries in the world, because of their carcinogenicity, mutagenicity and teratogenicity.Since the gases and particulates generated by human activities or natural processes release into the atmosphere, they eventually deposit to the ground as dust or fall to the earth in rain and snow. Atmospheric deposition including both dry and wet deposition is possible to return pollutants from air to the ground surface. PCDD/Fs and PBDD/Fs are mainly adsorbed on particulate matter in atmosphere, so dry and wet deposition are the main way of they are removed from the atmosphere. The town of Longtang, Qingyuan is an e-waste dismantling area mainly dismantles scrap wires and cables, the concern of the environmental pollution problems caused by e-waste dismantling activities followed by Guiyu, Guangdong and Taizhou, Zhejiang.In this study, the e-waste dismantling area of Longtang was chosen as the research target, and four sampling sites were selected. Site LT is situated in a school in the Longtang town, site QC is located in a leather factory in the Qingcheng District approximately 15 km north of Longtang, site YZ is located in the Qinzhan hot spring resort hotel approximately 8km south of Longtang, site TH is located in a scientific research institute in the Tianhe District, Guangzhou. Continuous sampling the atmospheric deposition of these four sites monthly over one year(October 2009- September 2010), and analysis the PCDD/Fs and PBDD/Fs in the deposition. The main results are summarized as follows: 1) The atmospheric deposition fluxes of seventeen 2,3,7,8-substitued PCDD/Fs were 6392.42、2249.14、1253.56 and 1250.53 pg m-2 day-1 at LT、QC、YZ and TH site respectively, the correspond TEQ fluxes were 309.56、64.37、32.92 and 35.40 pg WHO05-TEQ m-2 day-1. The congener profiles of 2,3,7,8-PCDD/Fs in deposition fluxes were dominated by 1,2,3,4,6,7,8-Hp CDF、OCDF and OCDD, the ones in the correspond TEQ fluxes were dominated by 2,3,4,7,8-Pe CDF、 1,2,3,4,7,8-Hx CDF and 1,2,3,7,8-Pe CDD. The relative abundance of 1,2,3,4,6,7,8-Hp CDF and OCDF is high in deposition of LT site, which meets the characteristics of PCDD/Fs released by the electric wires burning. The relative abundance of 1,2,3,4,6,7,8-Hp CDF and OCDF in QC and YZ sites is higher than that in TH site, which means the PCDD/Fs in atmospheric deposition at QC and YZ sites were affacted by the e-waste dismantling activities in Longtang, and the PCDD/Fs in atmospheric deposition at TH sites mostly affected by other pollution sources. The deposition fluxes in wet season were higher than those in dry season except at LT site. The homologue profiles distribution patterns of 2,3,7,8-PCDD/Fs in the deposition in wet season and dry season were constant at the same sampling site, indicating that the PCDD/Fs emission sources were similar in different seasons. There is a better negative correlation between lower-chlorinated homologs and the monthly average temperature than that between higher-chlorinated homologs and the monthly average temperature, but there are no obvious correlation at the other there sites. The correlation between PCDD/Fs homologs and the number of rainy days is better than the correlation between PCDD/Fs homologs and the amount of precipitation. The deposition fluxes of 2,3,7,8-PCDD/Fs were weakly related to the particle deposition fluxes, but those were strongly related to PCDD/Fs concentrations in particles. 2) The atmospheric deposition fluxes of eight 2,3,7,8-substitued tetra- to hexa- PBDD/Fs were 118.69、32.90、27.30 and 40.26 pg m-2 day-1 at LT、QC、YZ and TH site respectively, the correspond TEQ fluxes were 29.91、7.87、6.19 and 9.77 pg WHO05-TEQ m-2 day-1. The congener profiles of 2,3,7,8-PBDD/Fs in deposition fluxes and in the correspond TEQ fluxes were all dominated by tetra- and penta-PBDD/Fs. The homologue profiles distribution patterns of 2,3,7,8-PBDD/Fs in the deposition in wet season and dry season were constant at the same sampling site, indicating that the PBDD/Fs emission sources were similar in different seasons. There are no obvious correlation beween PBDD/Fs homologue profiles and the monthly average temperature. The deposition fluxes of 2,3,7,8-PBDD/Fs homologue profiles were negatively related to the amount of precipitation and the number of rainy days, and the correlation between PCDD/Fs homologs and the number of rainy days is better than the correlation between PCDD/Fs homologs and the amount of precipitation. There are no obvious correlation between the deposition fluxes of 2,3,7,8-PCDD/Fs and the particle deposition fluxes in dry season, but there are good correlation in wet season. The deposition fluxes of 2,3,7,8-PCDD/Fs were strongly related to PCDD/Fs concentrations in particles. 3) There were good correlations between the deposition fluxes of PCDD/Fs and PBDD/Fs and the TEQ deposition fluxes of PCDD/Fs and PBDD/Fs in QC、YZ and TH sampling sites. It means that the emission intensity of PCDD/Fs and PBDD/Fs’ s pollution sources are in keeping with temporal varition. But at LT site, that mostly owing to the diffirent pollution of PCDD/Fs and PBDD/Fs, or the burning wires mixed other bromine-containing electronic compounds. |
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