西安城区空气中挥发性有机物的污染特征和化学反应活性研究
发布时间：2019-04-01 18:43
【摘要】：伴随着经济高速发展,近年来西安城区近地面O3浓度明显升高,作为臭氧和光化学烟雾的重要前体物,VOCs的污染问题已经引起了广泛关注。本文基于2012年9月至2013年8月在西安市大气环境综合实验室观测空气中56个VOCs物种的浓度数据,开展了西安城区VOCs污染特征、化学反应活性和健康风险评价研究。研究结果表明,空气中VOCs的小时平均体积分数为73.78×10-9,其中烷烃、烯烃、芳香烃、炔烃的小时平均浓度分别为40.38×10-9、23.86×10-9、8.31×10-9、1.23×10-9。对西安空气中VOCs贡献率最大的是烷烃,占54.73%,其次是烯烃、芳香烃和炔烃,分别占总VOCs的32.34%、11.26%和1.67%,其中C2~C5的烷烃和乙烯、丙烯等是体积浓度较大的主要物种;空气中VOCs的月均浓度呈单峰分布,其中1、2月份VOCs的平均浓度在全年中较高,7、8月份平均浓度较低;空气中VOCs的关键组分在不同月份和季节中基本相同,这说明西安市城区空气中各VOCs物种的来源比较固定。总VOCs、烷烃、烯烃和芳香烃的日变化规律基本一致,在早中晚交通高峰时期为较高值,说明机动车尾气排放和燃料燃烧对西安城区空气中VOCs的影响较大。化学反应活性计算结果表明,西安VOCs与OFP的相关性较好,最大增量反应活性为3.6615mol·mol-1,化学反应活性较强。对OFP贡献最大的是烯烃,其次是烷烃和芳香烃,其贡献率分别为77.47%、12.75%和9.53%;西安城区空气VOCs中的关键活性组分是C2~C5的烯烃和甲苯、间/对二甲苯等芳香烃类物质。利用USEPA健康风险评价模型对西安空气中6种苯系物进行健康风险评价研究,结果显示西安空气中的VOCs对人体存在一定的健康风险。非致癌风险危害指数为2.44E-01,苯的致癌风险值为4.25E-05,表明苯系物对研究区人群的非致癌风险处在安全范围之内;苯对研究区居民身体健康存在潜在的致癌风险。
[Abstract]:With the rapid development of economy, the concentration of O _ 3 near the surface of Xi'an City has increased obviously in recent years. As an important precursor of ozone and photochemical smog, the pollution of VOCs has been paid more and more attention. Based on the concentration data of 56 VOCs species observed in Xi'an Atmospheric Environment Laboratory from September 2012 to August 2013, the characteristics of VOCs pollution, chemical reaction activity and health risk assessment in Xi'an urban area were studied. The results showed that the hourly average volume fraction of VOCs in air was 73.78 脳 10 脳 10 9, and the hourly average concentrations of alkanes, alkenes, aromatic hydrocarbons and alkynes were 40.38 脳 10 ~ (9), 23.86 脳 10 ~ (9), 8.31 脳 10 ~ (9) and 1.23 脳 10 ~ (- 9), respectively. The largest contribution to VOCs in Xi'an was alkanes, accounting for 54.73%, followed by olefins, aromatic hydrocarbons and alkynes, accounting for 32.34%, 11.26% and 1.67% of total VOCs, respectively. Among them, alkanes and ethylene of C2~C5, Propylene is the main species with high volume concentration. The monthly mean concentration of VOCs in the air showed a single peak distribution, in which the average concentration of VOCs in January and February was higher in the whole year, and lower in July and August. The key components of VOCs in the air were basically the same in different months and seasons, which indicated that the sources of VOCs species in the air of Xi'an city were relatively fixed. The diurnal variation of total VOCs, alkanes, olefins and aromatic hydrocarbons is basically the same, with a high value in the peak period of early, middle and late traffic, indicating that the exhaust emissions of motor vehicles and fuel combustion have a great effect on the VOCs in the air of Xi'an urban area. The results of chemical reaction activity calculation show that Xi'an VOCs has a good correlation with OFP, the maximum incremental reaction activity is 3.6615mol 路mol-1, and the chemical reaction activity is strong. The largest contribution to OFP was olefins, followed by alkanes and aromatics, which contributed 77.47%, 12.75% and 9.53%, respectively. The key active components of VOCs in urban air of Xi'an are olefins and toluene, m / p xylene and other aromatic hydrocarbons of C2~C5. The USEPA health risk assessment model was used to evaluate the health risks of six benzene derivatives in Xi'an air. The results showed that VOCs in Xi'an air had certain health risks to human body. The non-carcinogenic risk hazard index is 2.44E 路01and the carcinogenic risk value of benzene is 4.25E 路055.This indicates that the non-carcinogenic risk of benzene to the population in the study area is within the safe range, and benzene has potential carcinogenic risk to the health of residents in the study area.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X511
本文编号：2451785
[Abstract]:With the rapid development of economy, the concentration of O _ 3 near the surface of Xi'an City has increased obviously in recent years. As an important precursor of ozone and photochemical smog, the pollution of VOCs has been paid more and more attention. Based on the concentration data of 56 VOCs species observed in Xi'an Atmospheric Environment Laboratory from September 2012 to August 2013, the characteristics of VOCs pollution, chemical reaction activity and health risk assessment in Xi'an urban area were studied. The results showed that the hourly average volume fraction of VOCs in air was 73.78 脳 10 脳 10 9, and the hourly average concentrations of alkanes, alkenes, aromatic hydrocarbons and alkynes were 40.38 脳 10 ~ (9), 23.86 脳 10 ~ (9), 8.31 脳 10 ~ (9) and 1.23 脳 10 ~ (- 9), respectively. The largest contribution to VOCs in Xi'an was alkanes, accounting for 54.73%, followed by olefins, aromatic hydrocarbons and alkynes, accounting for 32.34%, 11.26% and 1.67% of total VOCs, respectively. Among them, alkanes and ethylene of C2~C5, Propylene is the main species with high volume concentration. The monthly mean concentration of VOCs in the air showed a single peak distribution, in which the average concentration of VOCs in January and February was higher in the whole year, and lower in July and August. The key components of VOCs in the air were basically the same in different months and seasons, which indicated that the sources of VOCs species in the air of Xi'an city were relatively fixed. The diurnal variation of total VOCs, alkanes, olefins and aromatic hydrocarbons is basically the same, with a high value in the peak period of early, middle and late traffic, indicating that the exhaust emissions of motor vehicles and fuel combustion have a great effect on the VOCs in the air of Xi'an urban area. The results of chemical reaction activity calculation show that Xi'an VOCs has a good correlation with OFP, the maximum incremental reaction activity is 3.6615mol 路mol-1, and the chemical reaction activity is strong. The largest contribution to OFP was olefins, followed by alkanes and aromatics, which contributed 77.47%, 12.75% and 9.53%, respectively. The key active components of VOCs in urban air of Xi'an are olefins and toluene, m / p xylene and other aromatic hydrocarbons of C2~C5. The USEPA health risk assessment model was used to evaluate the health risks of six benzene derivatives in Xi'an air. The results showed that VOCs in Xi'an air had certain health risks to human body. The non-carcinogenic risk hazard index is 2.44E 路01and the carcinogenic risk value of benzene is 4.25E 路055.This indicates that the non-carcinogenic risk of benzene to the population in the study area is within the safe range, and benzene has potential carcinogenic risk to the health of residents in the study area.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X511
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