The Changes of PM2.5, BC, Elements and Pollution Sources Using Nuclear Technology in Xinzhen, Beijing Over the Past Decade

Abstract The concentrations of PM2.5, black carbon (BC), elements as well as sources of pollution in Beijing from 2003 to 2018 were investigated. The results show that the concentrations of PM2.5 and BC had similar annual and seasonal trends, especially in autumn-winter, which with declining trends in recent years. The proportion of BC in PM2.5 reduced from 13% in 2013(max) to 8.5% in 2018(min), indicating the reducing measure of replacing coal boiler with gas boilers worked well. In this study, annual trends of 15 elements were also discussed, it is found that the concentrations of S, K, Mn, Ca, Pb, Cu, Mn and Fe displayed remarkable decrease these years. Br, Zn and Cl was growing overall and Cl was more concentrated in PM2.5 in autumn and winter. Moreover, the In detected by NAA with high sensitivity may be a new and crucial fingerprint element associated with coal combustion, industry emission or biomass combustion because of correlation with BC, Na, K, Cu and halogen elements well. Finally, 6-factor solution was identified during 2007 and 2016-2017 by EPA PMF, and the proportions of some pollution sources changed a lot in PM2.5. Soil management in north China reduced the soil and dust source by 9.2%; The contribution of Industry-S or secondary S showed decrease from 27.5% to 22.5% due to industries relocating , gasoline with sulfur optimization and coal burning restriction; Banning straw burning and waste incineration in 2007 kept biomass and waste combustion out gradually. However, initial stage of some policies maybe the main reasons for a small increase of coal combustion source despite some steps taken.