Study On Spatial And Temporal Variation Characteristics And Source Of Atmospheric Fine Particulate Matter PM_2.5 In Beijing-Tianjin Region

In order to study the spatial and temporal variation characteristics and sources of PM_2.5 mass concentration in Beijing and Tianjin area,this paper is based on the research of the Chinese Research Academy of Environmental Sciences and the Wuqing Tianjin field atmospheric observation station,the monitoring method of PM_2.5 mass concentration in the two area is described in detail,the working principles,operating procedures and routine maintenance of the experimental instruments used in the two areas are described in a comprehensive way,and the quality assurance and quality control of the experimental process and the experimental data are introduced.According to the PM_2.5 mass concentration data of Chinese Research Academy of Environmental Sciences observation site from August 2007 to July 2014,during this period the temporal variation characteristics and sources of PM_2.5 mass concentration were analyzed in Beijing area.Study found that the average annual value of PM_2.5 mass concentration in Beijing area showed a downward trend,but it was still in a high concentration level in recent years.The seasonal order for PM_2.5 mass concentration from high to low was autumn,winter,spring and summer,the average concentration was 111.6 ?g/m³,94.8 ?g/m³,77.2 ?g/m³,70.5 ?g/m³,respectively.The average value of PM_2.5 mass concentration showed a gradual increase in the last few years,this may be affected by the overall of Beijing-Tianjin-Hebei region.In the characteristics of monthly variation of PM_2.5 mass concentration,the highest average concentration was 125.3 ?g/m³ in November,and the lowest average concentration was 76.4 ?g/m³ in July.PM_2.5 mass concentration has obvious "weekend effect" and "holiday effect",and as early as 2012,the peak began to be smooth,this is likely to be affected by the fuel and emission standards for motor vehicles in Beijing region.The results of trajectory clustering showed that two types of locus from the south of the North China Plain and the west of Inner Mongolia are relatively large,and PM_2.5 mass concentration was higher in the air mass.Study on the characteristics of continuous heavy air pollution process and special time period in Beijing area,various types of heavy pollution process showed a downward trend year by year,and there are obvious characteristics changes.By taking strong pollution emergency control measures,the air quality in the area can be improved obviously.According to the PM_2.5 mass concentration monitoring data of Wuqing Tianjin observation station from August 2011 to July 2014,the temporal variation characteristics and sources of PM_2.5 mass concentration were analyzed in Wuqing area during this period,and compared with the PM_2.5 mass concentration monitoring data in Beijing area at the same time.The results show that the changes of PM_2.5 mass concentration in the two regions are consistent,however,there are some differences in some heavy pollution process.The difference of PM_2.5 mass concentration in the two areas in winter,it may be caused by different heavy pollution processes in the two regions.The differences in the early peak period between the two regions,it may be due to the Wuqing area in the implementation of the motor vehicle emission standards for five time later than the Beijing area.The results of trajectory clustering showed that the air mass from the eastern part of Shanxi,the way Hebei southwest of accounted for a relatively large,and PM_2.5 mass concentration was the highest in the air mass.And the air mass from the southeast of Shandong,the way south of Tianjin has the largest proportion,but the average value of PM_2.5 mass concentration is not very high.