【作者】 杨萍；

【导师】 陈景文；

【作者基本信息】 大连理工大学 ， 环境工程， 2008， 博士

【摘要】 多环芳烃（PAHs）是环境中广泛存在的一类典型的半挥发性有机污染物,主要来自于化石燃料和生物质的不完全燃烧。许多PAHs具有“三致”效应,对环境和人类健康具有较大危害,因而引起广泛关注。东北地区是我国重要的老工业基地之一,区域内重工业密集,人口众多,各类能源消耗量大。此外,该地区冬季取暖期较长,用于采暖的煤炭和生物质燃料使量较大。因此,东北地区的PAHs污染应该较严重。松科植物在环境中分布广泛,四季常青;松针具有脂含量高、比表面积大的特点,可以作为天然被动采样材料富集空气中半挥发性有机污染物（SOCs）,反映区域中SOCs污染水平与特征。本研究采集东北地区及典型城区（大连）广泛分布的雪松（Cedrus deodar）和黑松（Pinus thunbergii）的2年生松针样品,分析了松针中PAHs的含量,对该区域PAHs的污染水平、组成特征和主要来源等方面进行了研究。此外,还研究了沉降颗粒物对松针中PAHs的贡献、松针与土壤中PAHs分布特征的联系、及松针生理性质对其富集PAHs能力的影响。本研究的结果,有助于揭示PAHs在较大区域范围的浓度水平及分布规律,判析PAHs的来源,为东北老工业基地PAHs的污染预防和控制提供重要依据。考察了大连地区雪松松针中PAHs的浓度及分布特征。与世界其它城市相比,大连地区松针中PAHs处于中等污染程度。由于季风性气候的影响,大连地区春季较强的大气湍流和海、陆空气交换可以减轻大气和松针中PAHs污染,减小大连地区春、秋季松针中PAHs的浓度差异。随着距交通干线距离的增加,松针中PAHs浓度呈降低趋势,表明交通对松针中PAHs的影响非常显著。大连地区松针中PAHs以3环和4环PAHs为主。随着远离城市交通区,3环PAHs占∑PAHs的比例变化不大,4环PAHs的比例逐渐降低,而5,6环PAHs的比例略有增加。主成分分析表明,PAHs的气/固相分配行为对松针富集PAHs有重要影响。对PAHs来源判析表明:交通排放是大连地区松针中PAHs的主要来源,煤和生物质的燃烧对大连地区松针中PAHs也有重要贡献。随着远离市区,煤和生物质燃烧对松针中PAHs的贡献逐渐增加。通过清洗去除松针表面的颗粒物,研究了颗粒物沉降对松针中PAHs的贡献。结果表明,沉降颗粒物对松针中PAHs浓度的平均贡献（P）为（23.1±3.4）%,随着PAHs正辛醇/空气分配系数(logK_OA)的增大而增大。随着远离交通繁忙区,P值逐渐降低,呈交通繁忙区→非主干交通区→居民区及公园/海岛区依次降低的空间变化趋势。清洗前后松针中3环和4环PAHs浓度没有显著变化;5环和6环PAHs浓度有显著差异,但由于其在松针中所占比例较小（仅为2～5%）,因此对松针中PAHs组成特征的影响不显著。比较松针和土壤中PAHs的含量,发现大连市区土壤中PAHs浓度远高于松针中PAHs浓度。定义f为空气颗粒物中PAHs浓度占整个空气中PAHs总浓度（包括纯气态和颗粒物吸附态）的比例。将土壤中PAHs浓度经f值换算后,得到来自于大气颗粒物沉降的土壤中PAHs浓度(C_PS)。比较C_PS与清洗后松针中PAHs的浓度(C_WP),发现log(C_PS/C_WP)与PAHs的固/气相分配系数(logK_PA)及logK_OA具有显著的线性关系。利用苯并（a）芘（BaP）的浓度,可以有效指示松针中PAHs基于BaP的毒性当量（TEQ）。大多数土壤样品中PAHs基于BaP的TEQ远高于松针中TEQ。比较了雪松和黑松松针的生理性质对PAHs浓度影响。脂含量是决定不同种属松针中∑PAHs差异的首要因素。进行脂含量归一化后,不同种属松针中PAHs浓度具有较好的可比性。对于雪松和黑松,3环PAHs浓度与脂含量的回归方程的斜率约为4环PAHs的2倍,对于5环和6环的PAHs,未发现其浓度与脂含量之间的相关关系。这表明,随着分子量增大,PAHs更易于附着颗粒物上,较难被松针表皮蜡脂吸收进入松针内部。雪松和黑松松针的脂含量与其比表面积之间具有相反的变化规律,两种松针中∑PAHs与比表面积间变化规律亦相反。松针比表面积和气孔密度对5环和6环PAHs浓度有显著影响。对东北地区黑松松针中PAHs的研究表明:受冬季采暖影响,采暖期松针中PAHs的浓度明显高于非采暖期,采暖期与非采暖期松针样品中不同PAHs的分布特征无显著差异。松针中的PAHs以菲（32%）为主,其次为萘（26%）和荧蒽（18%）。15种PAHs之间以及与∑PAHs间具有显著的相关关系。随着采样点所处地理纬度的增加,PAHs浓度的分布呈现3个明显的峰值,分别位于铁岭、抚顺和吉林市。对PAHs的同分异构体的比值分析表明,东北地区松针中PAHs主要来自于煤和生物质燃烧,并受其它排放源的影响。对松针中典型PAHs比值的三角分布图分析表明,城市区与偏远地区松针中PAHs的主要来源具有一定的差异性。随着城市人口密度增大,松针中∑PAHs浓度增加。除大庆和盘锦外,东北地区主要城市的松针中∑PAHs随第二产业国内生产总值（GDP₂）与城市总GDP比值的增大而增加,两者呈显著正相关。不同城市第一、二和三产业GDP占总GDP的比例,对该区域松针中PAHs的浓度有重要影响。随着城市民用汽车拥有量的增大,主要城市松针中∑PAHs呈增加趋势,两者呈显著正相关关系。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons （PAHs）, a group of ubiquitous semivolatile organic compounds （SOCs）, are mainly originated from incomplete combustion of fossil fuel and biomass. Due to possible human carcinogens, PAHs have become an issue of increasing concern in recent decades. Northeastern area is one of typical traditional industrial bases in China. Over the last century, increases in population and industry in the region have resulted in high consumption of fossil fuel. In addition, biomass burning is a traditional practice for heating and cooking in rural areas. Thus, it was expected that Northeastern area might suffer from severe PAH pollution. Pine is most widely distributed conifer in the world. Due to lipid-rich cuticle and pore structure of its surfaces, pine needles have a high affinity for SOCs and can be used as passive samplers to monitor regional contaminations and to identify point sources of SOCs. The PAH levels in pine needles from Northeastern area and Dalian were investigated, which is very important to understand the characters of PAH pollution in Northeastern China. In addition, contributions of deposited particle bound PAHs, relationships of PAH profiles and distribution between pine needle and soil samples and influence of pine needle’s physiological properties on the capabilities of PAH accumulation were investigated.The levels and distribution of PAHs in Dalian pine （Cedrus deodar） needles were investigated. The strong turbulence and air exchange may facilitate air depuration effectively and also mitigate the diffusion of PAHs into the pine needles. Consequently, PAH concentrations were no statistically significant differences among the different sampling campaigns. The concentrations of PAHs in Dalian were comparable with that in other regions in the world. Pine needle PAH concentrations showed a major traffic areas - minor traffic -residential areas - city parks/island gradient. The profiles in all pine needle samples were dominated by 3- and 4-ring PAHs. The profiles of 4-ring PAHs decreased along the heavy traffic - minor roads - residential areas - city parks/island transect, whereas the franctions of 5- and 6-ring PAHs increased slightly among the four areas. The plots of selected PAH diagnostic ratios in the four sampling areas suggested that pine needle PAHs were mainly from traffic emission in the urban areas and coal/wood combustion in the suburban and rural areas.The contributions of deposited particles （P） to PAH levels in pine （Cedrus deodar） needles sampled from Dalian region were evaluated. The results showed that the average contributions of deposited particles （P） were （23.1±3.4）%, and positively correlated with logarithm of octanol/air partition coefficients (logK_OA) of each PAH significantly. P were high for traffic areas, and low for residential or park areas, implying the significant contributions of PAHs in both gas and particle phases emitted by vehicles. However, PAH profiles in pine needles were not significantly altered by the washing, due to the low fractions （2～5%） of the 5- and 6-ring PAHs in ZPAHs.The concentrations and profiles of PAHs in soil and pine neddle samples were investigated.ΣPAHs in soil samples are higher than in pine needles from Dalian areas. Significant correlations were observed between logarithm of particle/gas partition coefficient, as well as logK_OA, and logarithm of soil PAH concentrations from atmosheirc particle deposition vs. washed pine needle PAH levels. Benzo（a）pyrene （BaP） was a good indicator for assessing the potential toxicity of PAHs. Toxic equivalent concentrations based on the toxic equivalency factor of BaP of most soil samples are higher than pine needles.The influences of the physiological properties on the accumulation of PAHs in pine （Cedrus deodar and Pinus thunbergii） needles were investigated. The lipid content is the principal factor influencing the PAH levels in different species of pine needles. Pine needles are prone to accumulate gas phase PAHs, such as 3-ring PAHs. There are no significant correlations between the levels of 5- and 6-ring PAHs and lipid contents for two species. For two species, the correlations between lipid contents and specific surface areas are different, which result in the contrary correlations between the PAH levels and specific surface areas for Cedrus deodar and Pinus thunbergii. Specific surface areas and stomata density affect the levels of 5- and 6-ring PAHs in pine needles significantly.The levels and distribution of PAHs in pine （Pinus thunbergii） needles from Northeastern area were investigated. Due to high combustion of coal for heating in autumn and winter, PAH levels in pine needle samples were statistically significant differences between heating and non-heating periods, whereas insignificant differences of the PAH composition profiles by ring size were observed. Pine needle PAHs were dominated by phenanthrene, naphthalene and fluoranthene. With the latitude increasing, pine needle PAH concentrations in major cities presented three peak values in Tieling, Fushun and Jilin City, respectivly. The results of diagnostic ratios indicated that pine needle PAHs in the study area were mainly from incomplete combustion of coal and/or biomass, and were affected by other emission sources, too. Significant correlations were observed between population densities and pine needle PAHs in major cities as well as the ratio of second gross domestic product （GDP） vs. total GDP. High traffic densities could lead to high XPAHs.更多还原