• 关键词：细颗粒物（PM_2.5）  化学组成  来源解析  重庆

• 基金项目：环境保护部公益项目（No.201009001）；北京市组织部优秀人才培养资助（No.2014000020124G119）；2016年首都经济贸易大学中青年骨干教师基金

• 陈源
• 首都经济贸易大学安全与环境工程学院, 北京 100070

• 谢绍东
• 北京大学环境科学与工程学院, 北京 100871

• 罗彬
• 四川省环境监测中心, 成都 610041

• 翟崇治
• 重庆市环境监测中心, 重庆 401147

• 摘要：重庆市主城区大气细颗粒物（PM_2.5）浓度从1990s的>100 μg·m^-3下降至当前的约70 μg·m^-3,但仍高于环境标准限值.为探讨重庆市主城区PM_2.5化学组成与来源特征,于2012—2013年在渝北区大气超级站利用四通道采样仪连续采集了颗粒物样品,分析了其中水溶性离子、碳质组分和无机元素含量.采样期间,重庆市主城区大气PM₁₀和PM_2.5的年日均浓度分别为103.9和75.3 μg·m^-3,扩散条件不利的冬季,细颗粒物污染较为严重.受静稳天气影响的1月和2月,受沙尘影响的3月,及二次转化显著的6月是重庆市细颗粒物污染较重的月份.重庆市PM_2.5组成以有机物（OM,30.8%）为主,其次为硫酸盐（SO₄^2-,23.0%）、硝酸盐（NO₃^-,11.7%）、铵盐（NH₄⁺,10.9%）、地壳物质（Soil,8.2%）、元素碳（EC,5.2%）、K⁺（1.1%）、Cl^-（1.0%）和微量元素（Trace,0.6%）.较高的SO₄^2-浓度和逐步上升的[NO₃^-]/[SO₄^2-]比值反映了重庆市燃煤污染较重,同时机动车污染比例逐步增加.采用主因子分析/绝对主因子得分法解析了重庆城区细颗粒物5类主要来源是：二次粒子（41.7%）、燃煤（15.6%）、建筑/道路尘（12.4%）、土壤尘（11.0%）和工业尘（10.4%）,通过各污染源季节变化及与其他结果对比,该源解析结果能够较可靠反映重庆市细颗粒物的来源信息.

• Abstract：Concentrations of fine particles (PM_2.5) in urban Chongqing has decreased from >100 μg·m^-3 in 1990s to about 70 μg·m^-3, but is still much higher than the national air quality standard. To investigate the chemical composition and source characteristics of PM_2.5, samples were collected in the monitoring supersite of Yubei District during 2012—2013 using a four-channel sampler. The content of water-soluble ions, carbonaceous aerosols and inorganic elements were analyzed. During the sampling period, the annual daily average PM₁₀ and PM_2.5 concentrations in urban Chongqing were 103.9 and 75.3 μg·m^-3, respectively. Winter with unfavorable diffusion conditions was the most heavily polluted season in Chongqing. Monthly PM_2.5 levels were higher in January and February with frequent occurrence of stable weather, March with dust intrusion, and June with enhanced secondary transformation. Organic matter (OM) was the most abundant component in PM_2.5 (30.8%), followed by sulfate (23.0%), nitrate (11.7%), ammonium (10.9%), soil (8.2%), EC (5.2%), K⁺ (1.1%), Cl^- (1.0%) and trace (0.6%). The high concentration of sulfate and increasing [NO₃^-]/[SO₄^2-] ratio demonstrated equal importance of coal combustion and vehicular emission. Five major sources were apportioned by principal component analysis/absolute principal component scores (PCA/APCS) method, which were secondary inorganic aerosol (41.7%), coal combustion (15.6%), construction/road dust (12.4%), soil dust (10.4%), and industrial emission (10.4%). Comparison between the seasonal variations of each source and other studies indicated that the apportioned results could reflect reliable source characteristics of PM_2.5 in urban Chongqing.

• Key words：fine particle (PM_2.5)  chemical composition  source apportionment  Chongqing

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