广州市大气中多环芳烃分布特征、季节变化及其影响因素

对广州市大气中气态和颗粒态多环芳烃(PAHs)进行了连续一年的采样观测.结果表明,气态和颗粒态样品中PAHs的平均浓度值分别为312.9 ng/m³ 和 23.7 ng/m³,即多环芳烃主要存在于气相中,占大气总PAHs年平均的92.5%,且在夏季的比重要高于冬季.所检出的的气态多环芳烃以芴、菲、蒽等低环数化合物为主,其中菲占了总含量的60%以上;颗粒态多环芳烃则以高环数的化合物为主,各化合物所占的比重相当,其相对浓度无显著差别.气态多环芳烃在夏季达到高值,冬季降为低值;而颗粒态与其相反,夏季低值,冬季达到高值.在所测定的气象条件中,温度在影响气态多环芳烃浓度变化的因素中占了绝对优势,其次为风速,其它气象因素未观测到有较明显的影响作用;对颗粒态多环芳烃来说,则无绝对的影响因素,温度、风速和湿度同为重要影响因素,但随着分子量的增加,各因素的影响大小顺序略有不同.

Characteristics and Seasonal Variations and Influence Factors on Polycyclic Aromatic Hydrocarbons in Guangzhou City

Weekly particulate and gas phase polycyclic aromatic hydrocarbons (PAHs) were sampled by a modified high-volume sampler in Guangzhou city from April 2001 to March 2002. The average total gas and particulate concentrations (sigma PAHs) were 312.9 ng/m3 and 23.7 ng/m3, respectively. The predominant PAHs in the air were 2 to approximately 4-ring compounds in vapor phase. Clear seasonal trends were observed, with higher concentration in summer and lower in winter for gas phase PAHs and adversely for particulate phase PAHs. Ambient temperature was predominating factor influencing the variation of gas phase PAHs concentrations and temperature together with wind speed and relative humidity were main meteorological parameters affecting the fluctuations of particle phase PAHs.