广州市大气可吸入颗粒物(PM_(10))中多环芳烃的季节变化

Seasonal Variation of Particulate Polycyclic Aromatic Hydrocarbons Associated with PM_(10) in Guangzhou, China

采集广州五山、荔湾(20020612～20030631)2个采样点共112个PM10样品进行了GCMS分析,结果表明:2采样点全年多环芳烃浓度范围为8.11～106.26ng·m-3,呈现出夏季低冬季高的特征.PAHs化合物的相对分布也呈明显的季节变化,5～6环PAHs的比重夏季比冬季高,而3～4环PAHs的比重冬季比夏季高.冬季PAHs可分为2种模式,不同模式之间PAHs的浓度和分布特征有明显的差异.统计结果表明,广州市多环芳烃浓度变化主要受气象条件的影响,风速(当温度<20℃时)和温度(当温度>20℃时)是影响多环芳烃浓度最主要的因素.此外,本研究还表明,汽车尾气排放是广州市大气颗粒物多环芳烃污染最主要的污染来源.

112 PM_(10)(particulates matter with aerodynamic diameter <10?μm) samples were collected at Liwan and Wushan site in Guangzhou between March 2002 and June 2003. Polycyclic Aromatic Hydrocarbons (PAHs) were analyzed with GC/MS. The results showed that PAHs exhibited the distinct from seasonal variation. The concentration of ∑PAHs ranged from 8.11 to 106.26?ng/m^3. The highest concentration of PAHs in PM_(10) was observed in winter, with the lowest level in summer. 5～6 rings of PAHs were the abundant compounds, which accounted for 65%～90% of ∑PAHs. Significantly seasonal variations were also found in the PAHs contribution pattern. 5～6 ring PAHs had a trend of higher relative contribution in summer, while 3～4 ring PAHs tended to have a higher contribution in winter. The temperature was a possible factor influencing on the PAHs distribution pattern. The PAHs concentration and distribution pattern fluctuated greatly in winter due to cold current. Based on the significant difference of temperature in winter, the samples were classified into two groups and the distribution and the abundance of the PAHs in two groups were significantly different. Meteorological conditions had a strong influence on the seasonal variability. The wind speed (when the temperature was less than or equal to 20℃) and the temperature (when the temperature was bigger than 20℃) were main influencing factors of the PAHs concentration. Furthermore, the diagnostic ratios suggested vehicle emission was the predominant sources for particulate PAHs in Guangzhou.