河南省18个城市大气污染物分布特征、区域来源和传输路径

河南省大气污染严重且与周边区域污染传输及交互影响明显，以2017年1、4、7和10月为研究对象，将河南省内18个地市的排放源分别标记，并应用于WRF-CMAQ溯源模型进行模拟.污染物分布结果表明，由于排放和气象的共同影响，河南省PM_2.5、NO₂和SO₂浓度表现为冬季最高，夏季最低.O₃-8h浓度的季节变化则为夏季最高，春季次之，冬季最低.不同季节间污染物浓度差距较大，河南省PM_2.5、NO₂和SO₂冬季浓度平均值分别是夏季的4.17、4.12和6.24倍，而O₃-8h在夏季的浓度是冬季的2.24倍.由于PM_2.5、NO₂和SO₂与一次排放关系密切且具有一定的同源性，这3种污染物的高值分布为北高南低，季节趋势较为一致.而O₃-8h季节分布差异较大，夏季气象条件有助于O₃的生成，O₃-8h高值主要分布于河南省东北区域；冬春秋季由于气象条件的抑制和NO_x的消耗O₃-8h高值主要分布在河南省的南部.传输结果表明，冬季省外传输和天然源对河南省PM_2.5、O₃-8h、NO₂和SO₂浓度的贡献率都是最大的，分别为36.20%~72.32%、77.96%~96.08%、49.45%~78.80%和59.05%~88.85%.在仅考虑本地排放和省内传输时，夏季河南省内各市的排放对本地4种污染物浓度的贡献率均为最高；春季省内传输对各市PM_2.5和O₃-8h浓度的贡献率较大，分别为25.63%~74.69%和30.21%~80.01%，冬季省内传输对各市NO₂和SO₂浓度的贡献率较大，分别为26.02%~76.96%和20.30%~82.34%.河南省内PM_2.5、NO₂和SO₂的传输路径相似，冬季多由北向南传输，春季多由西向东，西南向东北传输，夏季多由西南向东北传输，秋季多由北向南传输，但PM_2.5的传输更加复杂.而O₃-8h传输路径与其他3种较为不同，特别是在秋季O₃-8h由西南向东北的传输路径明显.

One-year Simulation of Air Pollution in Central China, Characteristics, Distribution, Inner Region Cross-transmission, and Pathway Research in 18 Cities

Air pollution in Henan province is serious and is significantly impacted by pollution transmission and interactions with surrounding areas. The emission sources in 18 cities in Henan province were labeled and applied to the WRF-CMAQ traceability model for simulation in January, April, July, and October of 2017. The pollutant distribution results showed that due to the combined influence of emissions and meteorology, the concentrations of PM_2.5, NO₂, and SO₂ in Henan province were the highest in winter and the lowest in summer. The seasonal variation in O₃-8h concentration was the highest in summer, followed by spring, and the lowest in winter. There was a large difference in pollutant concentrations between different seasons. The average concentrations of PM_2.5, NO₂, and SO₂ in winter in Henan province were 4.17, 4.12, and 6.24 times those in summer, respectively, whereas the concentration of O₃-8h in summer was 2.24 times that in winter. Since PM_2.5, NO₂, and SO₂ are closely related to primary emissions and have a certain homology, the distributions of high values of these three pollutants were higher in the north and lower in the south, and the seasonal trends were more consistent. The seasonal distribution of O₃-8h varied widely, with high O₃-8h values mainly distributed in the northeastern region of Henan province in summer, when meteorological conditions contributed to O₃ production; in winter, spring, and autumn, high O₃-8h values were mainly distributed in the southern part of Henan province due to the suppression of meteorological conditions and NO_x consumption. The results of the study on the transport of pollutants showed that extra-provincial transport and natural sources contributed the most to the concentrations of PM_2.5, O₃-8h, NO₂, and SO₂ in winter, with 36.20%-72.32%, 77.96%-96.08%, 49.45%-78.80%, and 59.05%-88.85%, respectively. When considering only local emissions and intra-provincial transmission, the contributions of emissions to local concentrations of the four pollutants in summer were the highest in all cities of Henan province. The contributions of intra-provincial transmission to PM_2.5 and O₃-8h in spring were the largest, with 25.63%-74.69% and 30.21%-80.01%, respectively, and the contributions of intra-provincial transmission to NO₂ and SO₂ in winter were larger, with 26.02%-76.96% and 20.30%-82.34%. The transmission paths of PM_2.5, NO₂, and SO₂ were more similar in Henan province, with more transmission from north to south in winter, from west to east and southwest to northeast in spring, from southwest to northeast in summer, and from north to south in autumn; however, the transmission of PM_2.5 was more complicated. The O₃-8h transport path was more different from the others, especially in autumn when pollutants were mostly transported from north to south, but the O₃-8h transport path from southwest to northeast was obvious.