【作者】 顾庆平；

【导师】 陈立民；

【作者基本信息】 复旦大学 ， 环境科学， 2009， 硕士

【摘要】 多环芳烃(PAHs)是环境中广泛存在的一类具有致癌和致畸活性的有机污染物,对环境和人体的危害较大。除常见化石燃料燃烧外,生物质燃烧也是PAHs的重要来源之一。我国西藏地区由于发展水平相对落后,人群的空气污染暴露模式与其他地方相比,具有特殊性和典型性。并且,目前对于西藏地区燃烧源所产生的室内PAHs污染的相关研究尚未见报道。为了解西藏农牧区民居室内PAHs浓度水平及特征,评估其对居民的致癌风险,本研究于2006年5月～2007年8月在西藏自治区选取典型的农牧区,实地采集农区的冬夏季样品和牧区的夏季样品(由于气候和交通原因,缺失牧区冬季样品),测定西藏民居室内PAHs的浓度水平,分析不同燃烧源产生的PAHs污染特征,并以此评估PAHs对西藏居民的致癌风险,得出了以下结论:(1)西藏农区室内PAHs的平均浓度和组成均显示出明显的季节差异性。冬季室内PAHs的平均浓度达到564ng/m~3,约为夏季的1.5倍;组成中高分子量4+5+6环PAHs的比例高达66%,远大于夏季的32%。(2)西藏农村室内PAHs的全年平均浓度可达729ng/m~3,其中苯并芘(BaP)的浓度达到国家标准(10.0ng/m~3)的6倍以上。室外PAHs浓度较低,且只检测出16种优控PAHs中的7种低分子量组分。(3)西藏室内PAHs污染和致癌风险因炉具类型的不同而具有很大差异,其中采用火塘为炉具的室内PAHs浓度最高。在类似的地理环境下,以牛粪饼为燃料,使用火塘的室内PAHs平均浓度约为铸铁炉的8倍,可达到2389 ng/m~3。而通常使用火塘的居民在室内活动时间更长,综合导致了该类居民所受致癌风险是使用铸铁炉居民的10倍左右。(4)对比牛粪、木材、天然气三种燃料燃烧产生的产物来看,木材燃烧排放的PAHs日均平均浓度最高,牛粪次之,天然气最低;三者燃烧均排放了16种优控PAHs,其中天然气燃烧排放的PAHs中高分子量组分更占优势,木材燃烧排放的PAHs的种类最多;而牛粪燃烧排放的PAHs的特征与目前已知的燃烧源均不一致,有其独特的特征。(5)西藏居民所受致癌风险的大小受到炉具和燃料选择的影响。与开放式火塘相比,排烟系统良好的铸铁炉更能降低居民所受潜在致癌风险;以铸铁炉为炉具,使用天然气时居民所受潜在致癌风险分别是使用牛粪和木材时的1/2和1/3倍。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons(PAHs) are a kind of widely existed organic carcinogen which is very detrimental to the environment as well as the human being. Besides the buming of fossil fuels,PAHs can also be generated from the combustion of bio-related materials.The economy in Tibet is less developed;the pattern of the Tibet people being exposed to polluted air is unique and special compared with other regions.But no relevant research is reported ever before.To reveal the characteristic and the concentration of PAHs in Tibet as well as assess its potential of causing cancer to people.This research,which was carried out during from May 2006 to August 2007,collected sample on site from farming area in both winter and summer,and from pastoral areas in summer(due to limitations of traffic and climate,the sample in winter was not collected).We measured the concentration of PAHs under the indoor condition and analysis the properties of PAHs pollutant generated by each different fuels.We also assess their cancer-causing potential and draw the following conclusions:(1) The concentration of PAHs indoor is significantly season-related.In winter it is 564ng/m~3,which is about 1.5 times as high as that of summer.The 4-,5- and 6-ring PAHs make up to 66%of the total amount of all PAHs,far excess the ratio of 32%in summer.(2) The annual average concentration of PAHs indoor in Tibet village is up to 729ng/m~3,among them,the concentration of BaP is 6 times as high as the maximum tolerable value set by the national standard.Concentration in outdoor is lower;we only detected 7 Low Molecular Weight PAHs of all the 16 PAHs.(3) The indoor PAHs pollution and its cancer-causing potential are highly dependent on the oven.Under the same geologic conditions and taking cow dung as fuel,the stoves generate the highest density of PAHs concentration of 2389 ng/m~3,which is 8 times as high as that produced by the iron oven.People who use stove suffer from a 10-time higher risk than those who use iron oven.(4) After comparing the different concentration of the PAHs and its characteristic generated by cow dung,wood and LPG,it is found that all the three fuels emit sixteen PAHs when burning.LPG emits least amount of PAHs which also contains fewer High Molecular Weight PAHs.Cow dung emits the unique characteristics of PAHs which is not known before.(5) The risk of suffering from cancer is affected by the fuel and the oven.Compare with open stove,iron oven with smoke extraction system can reduce the user’s cancer-suffering risk.The Burning natural gas with iron oven brings the cancer-suffering risk which is only 1/2 and 1/3 of burning wood and cow dung.更多还原