利用PUF大气被动采样技术监测中国城市大气中的多环芳烃

利用PUF大气被动采样技术,分冬、春2个季度,对中国32个城市大气中的多环芳烃（PAHs）进行了观测.结果表明,除主要存在于气相中的2～3环PAHs与部分4环PAHs外,PUF被动采样器也可一定程度地采集大气颗粒物中的5～7环PAHs.中国城市大气PAHs的浓度与组成,主要受城市所处的地理位置、气候条件以及能源消费结构的影响.西北、华北、西南和华中地区部分城市大气中PAH总量和高环PAH浓度均较高,华南和东南沿海一带城市则相对较低.在季节变化上,表现为冬季浓度高、春季低.可能是陆源有机质在土壤中早期成岩作用的产物,春季浓度升高反映了土壤颗粒物对大气颗粒物的贡献,与扬尘天气相对应;而芴的浓度在燃煤较多的城市大气中显著增加,与其主要属燃煤成因相一致.研究表明,PUF大气被动器可很好地运用于区域大气PAH污染分布与特征对比研究.

Monitoring of Polycyclic Aromatic Hydrocarbons in the Atmosphere of China Cities Using PUF-Passive Air Sampler

A national-wide survey of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere was conducted in 32 cities in China during winter and spring, respectively, in 2005. Polyurethane foam passive samplers (PUF-PAS) were used to collect PAHs in the atmosphere. The results show that PUF-PAS may not only absorb 2~3 ring PAHs and part of 4 ring PAHs, which mainly exist in vapor phases, but is also able to retain 5~7 ring PAHs mostly associated with atmospheric particulates. Higher concentrations of total PAHs and high molecular weight PAHs were observed in the cities located in northwestern, northern, southwestern and central China, while relatively low PAH concentrations were found in cities located in southern China and/or along the eastern coastal regions. By comparing the two seasons, PAH concentrations in winter are higher than in spring. Geographical location, climate and energy consumption patterns were found to be the main factors influencing the concentrations and profiles of PAH in the urban air. Molecular markers indicated that the PAHs in urban air were mainly resulted from incomplete combustion of fossil fuel. Given that most of perylene is resulted from early diagenesis of organic matter in soil, its higher concentrations in spring than in winter may indicate a higher contribution of eolian soil to the atmospheric particulates in spring owing to the stronger wind and snow melting in North China. Higher concentrations of fluorene were observed in cities with higher coal consumption, in consistence with its coal combustion origin. The results demonstrated that PUF-PAS technique can be used in the monitoring of PAHs in the atmosphere at a regional or global scale.