Spatiotemporal Patterns and Cause Analysis of PM 2.5 Concentrations
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Hindawi Advances in Meteorology Volume 2018, Article ID 1724872, 8 pages https://doi.org/10.1155/2018/1724872 Research Article Spatiotemporal Patterns and Cause Analysis of PM2.5 Concentrations in Beijing, China Guangjin Tian ,1 Xiaojuan Liu,2 and Lingqiang Kong2 1 School of Government, Beijing Normal University, Xinjie Kouwai Street, Beijing 100875, China 2State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Xinjie Kouwai Street, Beijing 100875, China Correspondence should be addressed to Guangjin Tian; [email protected] Received 5 October 2017; Revised 28 November 2017; Accepted 30 November 2017; Published 15 February 2018 Academic Editor: Julio Diaz Copyright © 2018 Guangjin Tian et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. According to the monthly comprehensive air index ranking in China in 2016, Beijing ranked in the bottom tenth three times, indicating that the air pollution situation is very serious compared to other cities in China. In this study, we chose 23 urban environmental assessment points, which covered all districts and counties in Beijing. We used ArcGIS sofware to analyze atmospheric concentrations of particulate matter with a diameter < 2.5 �m(PM2.5)foreachmonthof2016ineachdistrict/countyof Beijing. Our results showed that PM2.5 concentrations in winter and spring were generally higher than those in summer and autumn. Te higher monthly average PM2.5 concentrations were primarily in the southwest and southeast areas. Te higher annual average values were distributed in Fangshan, Daxing, and Tongzhou, which were closely related to the high terrain in the northwest and the low-lying terrain in the southeast, the “Beijing Bay” terrain, and local climatic conditions. Te temporal and spatial distributions of PM2.5 constitute a warning signal for human life and production during diferent seasons and regions. 1. Introduction as a foreign body, is phagocytized by macrophages, causing an infammatory reaction. In addition, PM2.5 also damage In recent years, the frequent occurrence of haze events the cardiovascular and nervous systems. Although PM2.5 has gradually infuenced human health and living. Te particles are small, a large number of toxic and harmful composition of haze is very complex, including hundreds substances readily attach to them. Particles attached to toxic � of atmospheric particles [1]. Aerosol particles 10 min substances have the characteristics of long duration and long- diameter are the most harmful particles for human health: distance transportation in the atmosphere, causing a greater foating dust, aerosols, and inhalable particles can directly impactonhumanhealthandtheatmosphere. enter the human body and adhere to the upper and lower In February 2012, the State Council of China revised respiratory tract and lungs, causing rhinitis, bronchitis, and and issued an Ambient Air Quality Standard (GB3095-2012), other diseases. Tese particles will induce lung cancer if in which PM2.5 was added as a new monitoring indicator. > they exist in this environment for a long time. Particles PM2.5 is equivalent to 1/20 the diameter of a human hair, � � 10 m do not easily enter the respiratory tract. Most 5–10 m and particles of this size directly enter the lungs. Although particles are deposited in the upper respiratory tract, whereas PM2.5 content is very small compared to other components most 2.5–5 �m particles are deposited in the bronchioles and of the Earth’s atmosphere, they have important implications < � alveoli. However, about 75% of particles 2.5 m(PM2.5) for air quality and visibility. In 2013, PM2.5 was identifed as in diameter are deposited in alveoli. Because the alveolar a primary carcinogen by the International Cancer Research area has a large surface area and the alveolar wall has an Institute. Te composition of PM2.5 is very complex and abundant capillary network, the soluble fraction (including mainly depends on the source, which can be natural (soil some heavy metals) is easily absorbed into the blood and dust, volcanic eruption, and forest fres) or anthropogenic hasefectsinthehumanbody,whiletheinsolublefraction, (burning of fossil fuels, emission of motor vehicles, and 2 Advances in Meteorology burning and dust of straw waste), which are the most harmful 140.0 128.2 to human health [2]. Secondhand smoke is a major source of 120.0 PM2.5, followed by cooking fumes. Te frequent hazy weather 93.5 100.0 90.7 in Beijing is caused by several factors, including industrial 83.2 development, coal-based energy consumption, and increases 80.0 65.8 65.9 67.4 in motor vehicle ownership and urban construction projects. 57.2 60.0 52.6 53.2 Te objective of the present study was to investigate the 41.9 45.0 temporal and spatial patterns of PM2.5 in Beijing in 2016 and 40.0 to analyze the causes of their formation. Te fndings pro- vided by this study will support environmental policymakers 20.0 whoshouldmakeinformeddecisionspertainingtourban 0.0 planning to mitigate atmospheric pollution events in Beijing. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1: Monthly average particulate matter with a diameter < � 2. Data and Methods 2.5 m(PM2.5) concentrations in Beijing in 2016. 2.1. Data Sources. In this study, we selected 23 urban environ- mental assessment points, covering all districts and counties- 3.1.2. Monthly Mean PM2.5 Concentration Distribution in 2.5 in Beijing, and collected data on the average PM concentra- Beijing. Figure 1 shows the monthly average PM2.5 con- tions in each month of 2016. Te data were in the fo0rm of centrations in Beijing in 2016. It is clear that the average monthly air quality data for Beijing, released by the Beijing PM2.5 concentration was highest in December (mean = 3 3 3 Environmental Protection Bureau (http://www.bjepb.gov.cn/ ∼133 �g/cm ,SD=21�g/cm versus ∼100 �g/cm ,SD= bjhrb/xxgk/ywdt/hjzlzk/dqhjzl/index.html), the National 3 13 �g/cm for November). Te average PM2.5 concentration Environmental Monitoring Station (http://www.tianqihoubao ∼ � 3 � 3 .com/aqi/beijing-201610.html), and the Zhenqi network in March 2016 was 92.8 g/cm (SD = 8 g/cm ). Signif- (https://www.zq12369.com/environment.php?tab=city&city= cant increases in PM2.5 concentrations were detected from %E5%8C%97%E4%BA%AC&order=desc#envtab). August to December. PM2.5-induced pollution in March andOctober–Decemberwasmoreseriousthaninother months, in which the average concentrations ranged from 3 2.2. Analytical Methods. Te data were preprocessed by 45 to 70 �g/cm . Fluctuations in summer and autumn were 3 Excel, ArcGIS, and other sofware. We obtained the temporal small. Te lowest concentration, ∼43.5 �g/cm ,occurredin and spatial patterns of PM2.5 in Beijing in 2016. Based on February. Figure 1 shows that PM2.5 concentration declined the distribution characteristics and the present situation in in March, increased in August, and reached its maximum Beijing, we mainly focused on the spatial patterns, which have in December. Te mean PM2.5 concentrations in summer particular signifcance for constructing a ventilation corridor andautumnwerelowerthanthoseinwinterandspring, in Beijing. indicating better air quality during summer and autumn in Beijing. 3. Results and Discussion 3.1.3. Monthly Mean PM2.5 Concentrations in Beijing: District 2.5 3.1. Temporal Patterns of PM2.5 in Beijing in 2016 and County Data. Figure 2 shows the monthly average PM concentration distributions in the 16 districts and counties 3.1.1. Current Situation. Te Beijing-Tianjin-Hebei region of Beijing. We found that the PM2.5 concentration of each and surrounding areas (including Shanxi, Shandong, Inner county was lowest in February and around August. Statistical Mongolia, and Henan) sufer from severe pollution, which analysis showed that the concentrations in February and in 2016 in Beijing persisted for more than 40 days. For August were signifcantly lower than those in the other nearly half of the year, Beijing experiences a minimum of months (� < 0.05). Monthly average concentrations from light pollution, while March and October–December are ApriltoAugustineachcountywerealllow,butthediferences themajorpollutionseasons.Heavypollutionhasoccurred among these months were signifcant for each county (� < many times in Beijing in December, and 35.5% of days 0.05).TePM2.5 concentrations in districts and counties rose were considered a heavy pollution, which was signifcantly rapidly beginning in September and attained their highest higher than that in other months. Te annual average PM2.5 levels in December. Statistical analysis showed signifcant 3 concentration in Beijing in 2016 was 73 �g/cm ,whichwas diferences in monthly average concentrations among all reduced by 9.9% from the year earlier, and the annual average months (� < 0.05), except between May and September concentrations in 2016 of three other major atmospheric (� > 0.05). Overall, the concentrations at the district and pollutants, PM10, sulfur dioxide, and nitrogen dioxide, were county levels were consistent with the regionally averaged 3 92, 10, and 48 �g/cm , respectively, which were reduced by concentrations in Beijing. Moreover, the monthly changes in 9.8%, 28.6%, and 4.0%, respectively, compared with that in regional PM2.5 concentrations were signifcantly correlated the year earlier. It is undeniable that Beijing still experiences among