| Dioxins is one kind of permanent organic pollutant, including Dibenzo-p-dioxins(PCDDs) and dibenzofurans (PCDFs). Biochemical studies suggest that dioxins act as“human endocrine system”, tiny dose of dioxins may cause the disorder of the humanhormone secretion. Most of dioxins are not easily metabolic and play a role inbiological accumulation and biological amplification. Moreover, dioxins had beenlisted as No.1carcinogens by International Research Center of World HealthOrganization because of their carcinogenicity, teratogenicity and mutagenicity. Dioxinshas a strong adsorbability, which can be adsorbed on atmospheric dust and other media.They can not only enter into water and soil by deposition (dry and wet), but also causeglobal pollution by atmospheric circulation and migration. Therefore, it is necessary toanalyze the dioxin pollutants as well as their environmental behavior. This studyfocuses on the problems of environmental pollution brought about in the process ofeconomic development of the Pearl River Delta region due to the relative lack ofdioxin-contaminated data in this region. On the basis of USEPA1613、EPA23、HJ77.2-2008,17kinds of2,3,7,8-PCDD/Fs in56atmospheric samples, which come froma refuse incineration plant in Guangdong province were analyzed by high-resolutiongas chromatography/high-resolution mass spectrometry (HRGC/HRMS). Thepollution situation of dioxins in atmospheric environment of all sample sites and itsaffecting factors, including atmospheric deposition fluxes of PCDD/Fs,geographiclocation,climate and environment, were systematically investigated. Breathingexposure levels of all sampling sites was also be roughly estimated.(1) The study analysed and determined the dioxin concentration of56air samplescollecting from eight sampling sites. The results showed that the levels of PCDD/Fs at all sampling sites were higher, and the concentration of PCDD/Fs and WHO-TEQ werein the range of9.89-568pg/Nm3and0.502-41.8pg/Nm3, respectively. The maximumand minimum concentration of PCDD/Fs in all sampling sites were found at D and B,respectively. The maximum and minimum WHO-TEQ happened at D and G,respectively.(2) It was shown that the monomer concentration of dioxins in all samples hassimilar distribution trends,1,2,3,4,6,7,8-HpCDF and OCDF are the dominantcomponents. The distribution of dioxins homologue also has similar trends, and thetotal amount of PCDFs were significantly greater than PCDDs. Moreover, thecontribution rate of monomer toxicity equivalent of dioxins in all samples has veryconsistent trend,2,3,4,7,8-PeCDF and1,2,3,7,8-PeCDD are two largest contributors,followed by HxCDF.(3) There was a obvious combustion source at each sampling site because of∑PCDFs/∑PCDDs＞1and the content of high chlorinated compounds greatly higherthan that of low chlorinated compounds. There may be other polluted sources outside ofrefuse incineration plant owning to high concentrations of1,2,3,4,6,7,8-HpCDD/F andOCDD/F, for example, light or heavy diesel engine exhaust waste gas and so on.(4) The day breathing exposure levels of adults and children at all sampling siteswere in the range of1.82-0.538pg TEQ kg-1day-1and0.954-3.22pg TEQ kg-1day-1,respectively. The exposure levels were obviously higher compared to other cities.(5) The analytical results of dioxins in5vegetable oil samples showed that theaverage recovery of dioxin in calibration solution was60-121%with RSD<8.10%, andthe average recovery of PCDD/Fs was78.5-100.3%with RSD of2.2-8.4%. The resultsaccord with the requirement of EPA1613. The vegetable oil was safe base on thecontent and total toxicity equivalent results in five oil samples. |
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