昆明城区大气PM_(2.5)中PAHs的污染特征及来源分析

Characteristics and sources apportionment of PM_(2.5)-bound PAHs in Kunming

2013年4月至2014年1月期间,在昆明城区3个采样点采集了大气细颗粒物(PM2.5)样品,利用气相色谱-质谱联用仪对PM2.5载带的16种PAHs进行定量分析.结果表明:工业区(金鼎山)、交通密集区(东风东路)、清洁对照点(西山森林公园)PM2.5上PAHs平均含量分别为40.67,22.64,22.07ng/m3.通过常规气象因素及气团后向轨迹模型分析发现,起源于曲靖地区的污染气团传输及昆明大气高压形成的下沉气流是导致昆明PAHs浓度上升的重要原因.金鼎山、东风东路、西山森林公园的Ba Peq浓度分别为6.28,4.00,2.94ng/m3,均高于国家环境空气质量二级标准(2.5ng/m3).源解析结果显示,工业区(金鼎山)和交通密集区(东风东路)的PAHs污染来源一致,主要来自机动车排放,其贡献率分别为50.80%和40.20%,其次为燃煤排放,贡献率为35.55%和39.23%,再次为生物质燃烧,贡献率为7.30%和7.98%;作为清洁对照点的西山森林公园的PAHs则来自汽车尾气排放(81.84%)和生物质燃烧排放(9.73%).

A set of PM2.5 samples from three sampling sites belonging to the regional air monitoring networks of Kunming were collected during April 2013 to January 2014, and 16 selected PAHs were analyzed by GC-MS. Average concentrations of PM2.5-bound PAHs from the industrial area（Jinding Mountain）, traffic area（Dongfeng Tung Road） and clean area（Xishan Forest Park） were 40.67, 22.64, 22.07ng/m3. High atmospheric pressure and the input of air mass originated from the Qujing area were the cause of rising PAHs concentration in Kunming. Result of health risk assessment of PAHs showed, the concentration of Ba Peq at Jinding Mountain, Dongfeng Tung Road and Xishan Forest Park was 6.28, 4.00, 2.94ng/m3, respectively, exceeded the national ambient air quality standard（2.5ng/m3） in China. The PAHs in industrial area and traffic area were mainly influenced by vehicle emission（50.80% and 40.20%）, followed by coal combustion（35.55% and 39.23%）, biomass combustion（7.30% and 7.98%）; clean area was effected by vehicle emission（81.84%） and biomass combustion（9.73%）.