Characteristics of concentrations and chemical compositions for PM<sub>2.5</sub> in the region of Beijing, Tianjin, and Hebei, China

Abstract

Abstract. In order to study the temporal and spatial variations of PM2.5 and its chemical compositions in the region of Beijing, Tianjin, and Hebei (BTH), PM2.5 samples were collected at four urban sites in Beijing (BJ), Tianjin (TJ), Shijiazhuang (SJZ), and Chengde (CD), and also one site at Shangdianzi (SDZ) regional background station over four seasons from 2009 to 2010. The samples were weighted for mass concentrations and analyzed in the laboratory for chemical profiles of 19 elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, Sr, Ti, V, and Zn), eight water-soluble inorganic ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, and SO42−, and carbon fractions (OC and EC). The concentrations of PM2.5 and its major chemical species were season dependent and showed spatially similar characteristics in the plain area of BTH. The average annual concentrations of PM2.5 were 71.8–191.2 μg m−3 at the five sites, with more than 90% of sampling days exceeding 50 μg m−3 at BJ, TJ, and SJZ. PM2.5 pollution was most serious at SJZ, and the annual concentrations of PM2.5, secondary inorganic ions, OC, EC, and most crustal elements were all highest. Due to stronger photochemical oxidation, the sum of concentrations of secondary inorganic ions (NH4+, NO3−, and SO42− was highest in the summer at SDZ, BJ, TJ, and CD. Analysis of electric charges of water-soluble inorganic ions indicated the existence of nitric acid or hydrochloric acid in PM2.5. For all five sites, the concentrations of OC, EC and also secondary organic carbon (SOC) in the spring and summer were lower than those in the autumn and winter. SOC had more percentages of increase than primary organic carbon (POC) during the winter. The sums of crustal elements (Al, Ca, Fe, Mg, Ti, Ba, and Sr) were higher in the spring and autumn owing to more days with blowing or floating dust. The concentrations of heavy metals were at higher levels in the BTH area by comparison with other studies. In Shijiazhuang and Chengde, the PM2.5 pollution was dominated by coal combustion. Motor vehicle exhausts and coal combustion emissions both played important roles in Tianjin PM2.5 pollution. However, motor vehicle exhausts had played a more important role in Beijing owing to the reduction of coal consumption and sharp increase of cars in recent years. At SDZ, regional transportation of air pollutants from southern urban areas was significant.

The contribution of residential coal combustion to atmospheric PM<sub>2. 5</sub> in northern China during winter

“…7b. OC, EC, NH 4 were found to be the principal species, accounting for about 82-88 % of the total species in PM 2.5 at each sampling site, which is in line with previous studies (Zhao et al, 2013a; X. J. Zhao et al, 2013;Tian et al, 2014;Huang et al, 2014).…”

“…For example, coalfired power plants have been forced to install flue gas desulfurization and denitration (Zhang et al, 2012;Chen et al, 2014), coal has been replaced with natural gas and electricity in megacities (Wang et al, 2009;Duan et al, 2012;Zhao et al, 2013a;, stricter emission standards have been implemented for vehicles and industrial boilers (Zhang et al, 2012;Tang et al, 2016) and so on, resulting in a decreasing trend of primary pollutants including PM 2.5 in recent years Wen et al, 2016;Zhang et al, 2016). However, the PM 2.5 levels were still larger than 1000 µg m −3 in some areas of the Beijing-Tianjin-Hebei (BTH) region during the period of the red alert for haze in December 2016 (http://english.mep.gov.cn/News_service/ media_news/201612/t20161220_369317.shtml).…”

Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

“…Each group consists of several parallel experiments with various initial conditions of airborne pollutants or surface parameters. To investigate the impact of heterogeneity in vertical distribution 5 of BC on the dome effect, BC plumes with a width of 300 meters was settled at different altitude, ranging from the ground surface to about 2000 m. BC concentration was assumed to be 0~30 μg/m 3 according to existing field measurements across China Sun et al, 2004;Zhao et al, 2013a). BC concentrations in the plume was presumed to be a Gaussian distribution in vertical with maximum value that ranges from 0 to 30 μg/m 3 in the central axis, the altitude of which also ranges from 150 to 2250 m with an interval of 300 m. 10…”

Estimation of the direct and indirect impacts of fireworks on the physicochemical characteristics of atmospheric PM<sub>10</sub> and PM<sub>2.5</sub>

“…By scattering and absorbing incoming solar radiation and outgoing terrestrial radiation directly, or by acting as cloudcondensation nuclei and thereby influencing the optical properties of clouds indirectly, atmospheric aerosols can influence the radiation balance of the earth's atmosphere (Lin et al, 2013;Shen et al, 2013). Ambient PM is a complex mixture of components from a variety of sources, including those natural and anthropogenic (Zheng et al, 2005;Zhao et al, 2013a). In recent years, concerns about short-term air quality degradation events and their continuous negative effects on human health has increased, especially for PM pollution caused by high-intensity anthropogenic activities.…”