2015年阅兵限行减排措施对北京市环境空气PM_(2.5)中生物质燃烧排放有机物的影响

Research on Organic Matters from Biomass Combustion and Status of Atmospheric Environmental PM_(2.5) in Beijing before and after Emission Reduction Measures during the 2015 Military Parade

为了考察中国人民抗日战争暨世界反法西斯战争胜利70周年(大阅兵)北京及其周边地区施行的机动车单双号限行措施和工厂的限排减排措施对北京市环境空气中ρ(PM_(2.5))、生物质燃烧排放的有机化合物(包括左旋葡聚糖、甾醇类和多环芳烃类化合物)分布状况的影响以及生物质燃烧潜在的风险评估,采集了2015年8月10日—9月1日环境空气PM_(2.5)样品,采用快速溶剂萃取仪提取目标化合物并用气相色谱质谱仪进行分析.结果表明:2015年8月10日—9月1日,减排措施使城市点和交通点位的ρ(PM_(2.5))分别降低了23%和25%,减排加限行措施使得城市点、交通点和传输点3个点位的ρ(PM_(2.5))分别降低了44%、45%和66%.控制措施使3个点位的ρ(左旋葡聚糖)降低了92.4%~96.1%,减排措施起了关键作用;但对β-谷甾醇(生物质燃烧的另一个重要示踪物)和餐饮源的典型示踪物——胆固醇却几乎没有影响;生物质的不完全燃烧能够产生大量的PAHs类化合物,采样期间控制措施对3个点位PAHs的排放抑制作用有限,在城市点位中以左旋葡聚糖为示踪物的生物质在燃烧过程中比其他2个点位可排放更多的PAHs类化合物,表明城市点位的风险高于其他2个点位.研究显示,研究不同时期生物质燃烧排放的化合物种类及其质量浓度的变化,以及对于生物质燃烧所带来的风险进行评估,对于制订合理的控制措施、保护空气质量和人类健康具有重要的意义.

To study the influence of emission reduction measures and traffic controls on concentrations of PM2.5 and distribution of biomass combustion emissions including levoglucosan, sterol and polycyclic aromatic hydrocarbons （PAHs）, and evaluate potential risks from biomass combustion,PM2.5 samples of ambient air in Beijing were collected from August 10 to September 1,2015 （during the military parade to commemorate the Chinese people＇s Anti-Japanese War and the 70th anniversary of the world anti-fascist war）. The samples were extracted by accelerated solvent extraction system and analyzed by gas chromatography-mass spectrometer. The results showed that the concentrations of PM25 at urban and traffic positions were reduced by 23% and 25% respectively, through emission reduction measures during this period, and that the concentrations of PMz 5 at urban, traffic and junction positions were reduced by 44% ,45% and 66% respectively,through emission reduction measures and traffic controls. In addition, the emission reduction measures reduced 92.4% -96.1% of levoglucosan. However,beta sitosterol as the other important tracer of biomass combustion and cholesterol as the typical tracer of cooking emission, both reflecting local pollution sources emissions, had no obvious change through emission reduction measures at the three positions. The emission reduction measures had no inhibiting effects on PAHs partly resulting from biomass incomplete combustion. Meanwhile,risk assessment results showed that the biomass combustion emission of PAHs in the urban position,at which levoglucosan was used as the tracer of biomass, was higher than the other two positions, which indicated that the risk of urban position was higher. Therefore,it is important to study biomass combustion emissions and their concentrations during different periods and evaluate the risks, helping formulate reasonable control measures to protect air quality and human health.