摘要
摘要:采用卫星监测的火点燃烧排放数据，利用区域化学传输模式WRF-Chem模拟分析了2017年5月华北地区细颗粒物（PM2.5）质量浓度分布，通过生物质燃烧排放源（华北区域以秸秆燃烧为主）开关的敏感性试验定量计算了燃烧排放对北京及其周边地区PM2.5质量浓度的影响。卫星监测结果显示，2017年5月华北地区有大量的秸秆焚烧现象，对该地区空气质量造成一定影响的燃烧天数为20 d，占全月总日数的65%左右。数值模拟结果表明：该地区秸秆燃烧排放导致PM2.5浓度升高的区域集中在华北平原农作物产区，其分布位置与卫星监测的火点分布吻合。秸秆燃烧导致这些地区PM2.5浓度月平均值上升幅度普遍超过3 μg/m³，高值区超过了11 μg/m³，上升比例可达10%以上；此外，来自华北平原及长三角地区的燃烧排放对北京（特别是东南部地区）污染物浓度的影响是不容忽视的，其中河南、山东、天津等地的秸秆燃烧在合适风场的作用下会严重影响北京，可导致丰台及通州等地PM2.5小时浓度上升超过17 μg/m³，上升幅度超过40%。
关键词:秸秆燃烧/
北京/
细颗粒物(PM2.5)/
数值模拟
Abstract:Open biomass burning is an important source of air pollution in North China. The contribution of biomass burning to Beijing and its surrounding areas is quantified using a three-dimensional regional chemical transport model (WRF-Chem) with satellite-detected fire emissions inventory in May 2017 as input. It is found that there were 20 days with dense fires in North China during this month, which exerted great impact on regional air quality. Simulated results show that the biomass burning resulted in PM2.5 concentration increase mainly over major crop production areas in the North China Plain, which are consistent with the distribution of satellite-detected fire spots. Estimation based on model simulation indicates that open biomass burning contributes more than 3 μg/m³ to monthly averaged PM2.5mass concentration over the entire North China with the maximum contribution larger than 11 μg/m³, which accounts for more than 10% of the PM2.5mass concentration in some areas. The simulation also indicates that even if there is almost no fire spot in Beijing and the adjacent areas, biomass burning in the North China Plain and Yangtze River delta can still affect air quality in Beijing through long range transport process. A typical case review suggests that crop residue burning in Henan, Shandong, and Tianjin can significantly affect southeastern portion of Beijing, and leads to PM2.5 concentration increase by more than 17 μg/m³, which is equivalent to larger than 40% increase of the PM2.5 concentration.
Key words:Biomass burning/
Beijing/
PM2.5/
Numerical simulation



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