【作者】 董继元；

【导师】 王式功； 高宏；

【作者基本信息】 兰州大学 ， 环境科学， 2010， 博士

【摘要】 多环芳烃(PAHs)是一类典型的持久性有毒物质,主要来自化石燃料和生物质的不完全燃烧。多数多环芳烃(PAHs)具有“三致”效应。兰州是西北重要工业城市,能源消耗以煤为主,多环芳烃(PAHs)的污染不容忽视。兰州地区多环芳烃(PAHs)的来源、赋存状态、多介质环境行为和归趋,迄今尚不明确。因此,本文利用改进型的大流量主动采样器,于2008年8月到2009年7月对兰州市大气样品进行采集,并检测了气相和颗粒相中的多环芳烃(PAHs)的浓度。兰州市区大气中多环芳烃(PAHs)的分布存在明显的季节特征。16种多环芳烃(PAHs),总量的平均浓度冬季最高,明显高于其他三个季节。低环PAHs主要集中在气相,而高环PAHs则吸附在颗粒相上。沙尘天气发生时,大气颗粒物中多环芳烃的浓度显著上升,远远高于非沙尘天气期间,说明沙尘天气对兰州地区大气的多环芳烃浓度大小有直接的影响。在所分析的3种气象条件中,降水能够明显降低TSP中多环芳烃(PAHs)的浓度。非采暖期TSP和气相中的多环芳烃(PAHs)的浓度随温度的升高而降低,采暖期TSP和气相中的多环芳烃(PAHs)的浓度与温度没有明显的相关性。采暖期风速的增加,会导致TSP和气相中多环芳烃(PAHs)的浓度的下降,而非采暖期TSP和气相中不同环数的多环芳烃(PAHs)和风速大小之间的关系存在差异。通过特征分子比值法和主成分分析法推断出兰州市大气中PAHs的来源是燃烧源和石油源混合的结果,为混合输入型。以黄河兰州段11个不同采样点3种多环芳烃的监测浓度及其对6-38种水生生物的LC50为基础资料,分别应用商值法、概率密度函数重叠面积和联合概率曲线3种风险评价方法对黄河兰州段苯并[a]芘、荧蒽、芘的生态风险进行了评价。结果表明：黄河兰州段3种PAHs残留具有一定的生态风险。其中低暴露风险条件下(受威胁生物不超过1%),苯并[a]芘的风险性较大,荧蒽次之,芘风险相对较低；反之,在较高风险区间(约3%以上生物受到危害),危害化合物的影响大小顺序变为：芘>苯并[a]芘>荧蒽。通过对不同方法及评价结果的分析表明,联合概率曲线方法更适合于黄河兰州段PAHs的风险表征。近年来黄河兰州段的多环芳烃污染日渐严重。为研究黄河兰州段水体中多环芳烃类有机污染物对人体产生的潜在健康危害风险,根据黄河兰州段2004年11个采样点水质监测数据,应用美国环境保护局(USEPA)的健康风险评价方法对黄河兰州段多环芳烃类有机污染物通过饮水和皮肤接触2种途径进入人体的健康风险进行了初步评价。结果表明：黄河兰州段多环芳烃类有机污染物的非致癌风险指数均小于1,苯并[a]芘的致癌风险指数在10-4数量级以下；从位于西固八盘峡的1号采样点(S1)采集的水样中苯并[a]芘的致癌风险值偏高；在所有采样点中,西固八盘峡的1号采样点(S1)污染较重,具有较高的健康风险；与国内其他地区相比,黄河兰州段苯并[a]芘致癌风险亦较高。常规的自来水处理工艺不能有效地去除源水中微量PAHs等有机污染物,因此地面水特别是饮用源水PAHs污染具有较大的健康风险。在参照国外相关标准基础上,对兰州地区表层土壤PAHs进行区域环境风险评价。按照荷兰风险评价标准,兰州地区表层土壤萘、荧蒽超标严重,屈和茚并[1,2,3-cd]芘亦超标,ZPAH超标严重。运用逸度方法构建了兰州地区的III Level多介质逸度模型,对苯并[a]芘、荧蒽、芘在兰州地区不同环境相的迁移、转化和归宿进行了模拟研究。结果表明：大气的平流输入和化石燃料燃烧是该区域苯并[a]芘、荧蒽、芘的主要来源,土壤是苯并[a]芘、荧蒽、芘最大的储库,占总残留量的90%以上；土壤、大气中降解和随大气平流输出是苯并[a]芘、荧蒽、芘在兰州地区环境中的主要输出途径。系统内部最重要的跨界面迁移方式是气地和气水界面的交换。模型计算浓度与同期实测浓度吻合较好,验证了模型的可靠性,并通过灵敏度分析,确定了模型的关键参数。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons (PAHs) is a group of ubiquitous persistent toxic compounds, PAHs are mainly originated from incomplete combustion of fossil fuel and biomass. Lanzhou is an important industrial city in the northwest of China, and the fuel consumption in the Lanzhou area is mainly from coal, from which PAHs pollution can’t be neglected. By now, the source, state, and multimedia environmental fate or behavior of PAHs hadn’t been elucidated. Hence, air samples were collected using an improved high volume active air sampler August,2008 to July,2009 in Lanzhou City. Concentrations of polycyclic aromatic hydrocarbons(PAHs) in both gas and particle phases were measured. The distribution of PAHs in atmosphere of Lanzhou city has obviously seasonal characteristics. The average concentration of the sixteen kinds of PAHs in winter was highest, obviously higher than the other three seasons. Lower ring PAHs dominated in the gas phase, while the major higher ring PAHs were adsorbed on particle phase.When dust weather occurred, PAHs concentrations in TSP will increase significantly, much higher than non-dust weather. It is indicated that dust weather have direct effect on PAHs concentration of air in the Lanzhou area. Regarding to the meteorological parameters, precipitation distinctly lowered the PAHs concentration in TSP; in non-heating period, PAHs concentrations in both TSP and gas fall with the temperature goes up, but there is no obvious relation between concentration and temperature in heating period; the increase of wind speed causes the decrease of PAHs concentrations in both TSP and gas in the heating period, but relation between PAHs concentrations in both TSP and gas and wind speed varied with aromatic rings of PAHs and levels of wind speed in the non-heating period.Diagnostic ratios of some individual PAHs and principal component analysis were applied for qualitative source apportionment. According to above-mentioned analytical result, PAHs in atmosphere environment in Lanzhou originated both from combustion sources and the petrogenic source, showing a mixed PAHs input pattern.Based on the observed concentrations of polycyclic aromatic hydrocarbons in 11 surface water samples from the Lanzhou reach of the Yellow River and LC50 values of 6-38 of aquatic organisms, the quotient method and two probabilistic risk approaches were adopted to characterize ecological risks of benzo[a]pyrene, fluoranthene, and pyrene in water from the Lanzhou reach of the Yellow River. The results indicated that three residual PAHs carries some ecological risk. While at the lower exposure level (percent of species affected less than 1%), ecological risk of benzo[a]pyrene is the highest and that of pyrene was the lowest. Conversely, at the higher exposure level (percent of species affected more than 3%), the ecological risk of 3 individual PAHs followed the order of pyrene >benzo[a]pyrene> fluoranthene. In addition, comparing the results among the three approaches, the joint probability curve was the most appropriate method for risk characterization of PAHs in the Lanzhou reach of the Yellow River.The polycyclic aromatic hydrocarbons (PAHs) pollution of the Lanzhou reach of the Yellow River has been more and more serious in recent year. In order to investigate potential health risk to human bodies caused by organic pollutants of polycyclic aromatic hydrocarbons in waters there, based on water quality monitoring data from 11 sampling sites in the Lanzhou reach of the Yellow River in 2004, a preliminary assessment of the health risk caused by ingestion from drinking water and dermal contact with shower water was performed by using a health risk method of US EPA. The results showed that the non-carcinogenic risk indexes of organic pollutants of polycyclic aromatic hydrocarbons were far below 1. The carcinogenic risk index of benzo[a]pyrene was below 10"4. The carcinogenic risk value of benzo[a]pyrene at sampling site 1(S1) located in the Bapan Gorge of Xigu district was relatively high. Among all the sampling sites, the sampling site 1(S1) in the Bapan Gorge of Xigu district was the most heavily polluted, and might carry a higher health risk. Compared with other regions in China, the carcinogenic risk value of benzo[a]pyrene in the Lanzhou reach of the Yellow River were higher. The routine treatment technology of tap water can not remove effectively the trace organic pollutants (such as PAHs, etc). Therefore, the PAHs pollution of surface water carries a great health risk, especially when surface water is used as a drinking-water resource.Based on some foreign standards of soil PAHs assessment, regional environment risk assessment of topsoil PAHs in the Lanzhou area was done. Naphthalene, fluoranthene, chrysene and indeno[123-c,d]Pyrene in the topsoil of the Lanzhou area are exceed the standard of Holland.A level III fugacity model was used to calculate the transfer, transport, and fate of benzo[a]pyrene, fluoranthene, and pyrene in different compartments in the Lanzhou area. The results indicated that: advection inflows in air and combustion of fossil fuel were the major sources of benzo[a]pyrene, fluoranthene, and pyrene in this area, and soil was the largest storage of benzo[a]pyrene, fluoranthene, and pyrene, accounting for more than 90% of the total amount of residual. Degradations in soil, air, and advection outflow of atmosphere were main route of output. The transfer of between air to soil, and air to water surface is the most important transfer process among different compartments. The reliability of the model was verified by the coincidence of the calculated and the measured concentration in the same period. The key model parameters were identified through sensitivity analysis.更多还原