南京地区冬夏季大气重污染个例对比分析

本文研究了南京仙林地区在秸秆焚烧、逆温造成的大气污染的特征,分析了不同时期大气各成分的浓度变化.秸秆焚烧产生的大气污染事件中,颗粒物浓度上升最为显著,其中PM10的浓度最高可达0.65mg/m3,污染持续时间约36h.冬季污染期持续更长,但颗粒物峰值小于夏季,PM10浓度约在0.4mg/m3.根据Fernald方法反演得到的激光雷达消光系数计算不同高度AOD表明,秸秆焚烧造成的污染在空间上的分布较为均匀而冬季污染期近地表AOD的贡献超过40%.后向轨迹分析表明了污染期的气团在1500m高度的来源和1000m之下有差异,48h内的来源距离较短,近地表的大气质量受到周边地区的影响大,非污染期的气团垂直高度上性质较为均一,来源较为一致,来源距离较长.

Comparative analysis of winter and summer heavy atmospheric pollution events around Nanjing

This paper characterizes air pollution induced by combustion of crop residues in the Xianlin area of Nanjing under temperature inversion. Analysis of variations in the concentration of atmospheric pollutants in different periods reveals that combustion of crop residues causes a marked increase in the concentration of particulate matter in the atmosphere. These particulates are suspended in the atmosphere for up to 36hours, with a peak PM10 concentration of 0.65mg/m3. In winter they remain in the atmosphere longer, but have a lower peak PM10 concentration at around 0.4mg/m3 than in summer. According to AOD calculated from the LiDAR extinction coefficient derived using the Fernald method, the pollutants originating from combustion of crop residues have a more or less spatially uniform distribution at different heights, and contribute more than 40% towards near-surface AOD in winter. Back trajectory analysis demonstrates that during pollution the sources of air mass at 1500m differ from those below 1000m. It is found that within 48hours, the pollutants derive from relatively neighboring sources. Consequently, near-surface air quality is heavily affected by pollutants from the surrounding area. During no-pollution air mass comprises more vertically uniform constituents originating from more consistent and distant sources than during pollution.