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Mass Concentration Analysis and Comparative Study on PM2.5 in Beijing City,China in 2014
Pages: 309-317
Year: Issue:  3
Journal: Geology-Geochemistry

Keyword:  PM2.5 mass concentrationparalleled T/Qgravimetric analysisonline report;
Abstract: To grasp true pollution level and long term evolution of PM2.5in Beijing City,China,gravimetric analysis had been conducted simultaneously in CRAES,northern part of Beijing urban area during the periods from Dec. 2013 to Dec. 2014. Pairs of Teflon and quartz filters were employed as parallel for daily PM2.5mass concentration measuring,on behalf of 375 valid sample days. Statistical summary indicated that the PM2.5mass concentrations in winter were much higher than those in summer,with their peak value in February of 422. 1 μg / m3 and the lowest value in June of 6. 9 μg / m3,while the annual mean PM2.5was about 100 μg / m3.The T and Q groups showed positive correlation but the T / Q ratio differs with seasons. The most positive correlation was found in winter,with R2=0. 974 and T / Q = 1. 014,other two seasons also show higher T than Q,except spring. As T group served better than Q group,we chose T for linear-regression analysis with daily reported online data of PM2.5. Results showed the same seasonal variations,with the highest mass concentrations in winter,but difference distinct when PM2.5> 250. 0 μg / m3,because of the underestimation of online measurement. The monthly distribution of PM2.5pollution level proved that the best air quality appeared in summer,from April to August,while in winter it presented the most serious pollution,with over 50% of pollution days. After analyzing the comprehensive influence of RH and WS on PM2.5,we figured out that the primary cause of PM2.5pollution episodes was increased coal consumption needed in winter,combined with poor diffusion conditions such as low wind speed,high humidity and temperature inversion.
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