中国城市O_3浓度时空变化特征及驱动因素

Spatial-temporal Variation of Ozone Concentration and Its Driving Factors in China

基于2015～2017年O_3浓度监测数据,采用克里金插值、空间自相关分析、热点分析和地理探测器等方法,研究了中国城市O_3浓度的时空变化特征及驱动因素.结果表明:①2015～2017年中国城市O_3污染逐年加重,年评价指标超标城市由74个增加到121个,平均超标天数比例由5. 2%上升到8. 1%.②O_3污染主要发生在4～9月,超标天数占全年总超标天数的87. 5%～95. 3%. 5～7月O_3浓度上升最快、污染最严重,超标天数比例由2015年的10. 6%上升到2017年的20. 5%,2017年83. 0%的中度污染和91. 0%的重度污染发生在5～7月.③华北平原O_3浓度的持续上升,已将京津冀和长三角地区O_3高污染区连成一片,形成了包括环渤海地区、中原城市群、长三角城市群、山西、关中地区和内蒙古中部集中连片的O_3高污染区,是我国O_3污染最严重的区域.珠三角、成渝城市群和华东地区南部O_3浓度上升也较快,成渝城市群的核心城市已初步形成我国新的O_3污染中心.④O_3浓度空间集聚性逐年增强,年度热点主要分布在华北平原和长江中下游地区,冷点主要分布于东北、西南及华南地区.⑤地理探测器分析表明,气象、工业化、城市化因素和O_3前体物排放量因子对O_3浓度分布均有显著驱动作用,但不同地区O_3浓度的驱动因素存在差别,同一因子在不同季节的驱动作用也不尽相同.

Based on the ozone monitoring data from 2015 to 2017,this study presents the spatial-temporal variation of the ozone concentration and its driving factors in major cities in China via Kriging interpolation,spatial autocorrelation analysis,hotspot analysis,and geographical detector.The results show that:①The ozone pollution became increasingly heavier from 2015 to 2017,with the number of cities in which the 90 th percentile of daily maximum 8-h ozone concentration exceeded the air quality standard(GB 3095-2012)increased from 74 to 121,and the proportion of non-attainment days increased from 5.2 percent to 8.1 percent.②Ozone pollution mainly happened from April to September,during which the non-attainment days contributed 87.5 percent to 95.3 percent to the yearly total number of ozone polluted days.From May to July,ozone concentrations increased the most dramatically,with the proportion of non-attainment days increasing from 10.6 percent in 2015 to 20.5 percent in 2017.Moreover,in 2017,83.0 percent of the moderate ozone pollution and 91.0 percent of the severe ozone pollution happened from May to July.③With the ever increasing ozone concentration over the North China Plain,the high ozone polluted areas such as the Beijing-Tianjin-Hebei region and Yangtze River Delta urban agglomeration are connected geographically.They form the most highly polluted area in China,which includes the Bohai Rim region,Zhongyuan urban agglomeration,Yangtze River Delta urban agglomeration,Shanxi Province,Guanzhong area,and the middle part of Inner Mongolia.In addition,cities in Pearl River Delta region,Chengdu-and-Chongqing urban agglomeration,and the southern part of East China are also gathering speed in terms of ozone pollution,among which Chengdu-and-Chongqing urban agglomeration has become a new ozone-polluted center.④The spatial agglomeration of ozone concentration has been enhanced year by year with hot spots distributed mainly in the North China Plain and the middle and lower reaches of the Yangtze River.In contrast,there are cold spots in Northeast China,Southwest China,and Southern China.⑤The analysis results from geographical detector show that meteorological factors,industrialization,urbanization,and emissions of ozone precursors all have a significant effect on the distribution of the ozone concentration,but there are also discrepancies in the priority of the driving factors in different regions and seasons.