When investigating the impact of air pollution on health, particulate matter less than 2.5μm in aerodynamic diameter （PM2.5） is considered more harrnful than particulates of other sizes. Therefore, studies of PM2.5...When investigating the impact of air pollution on health, particulate matter less than 2.5μm in aerodynamic diameter （PM2.5） is considered more harrnful than particulates of other sizes. Therefore, studies of PM2.5 have attracted more attention. Beijing, the capital of China, is notorious for its serious air pollution problem, an issue which has been of great concern to the residents, government, and related institutes for decades. However, in China, significantly less time has been devoted to observing PM2.5 than for PM10. Especially before 2013, the density of the PM2.5 ground observation network was relatively low, and the distribution of observation stations was uneven. One solution is to estimate PM2.5 concentrations from the existing data on PM10. In the present study, by analyzing the relationship between the concentrations of PM2.5 and PM10, and the meteorological conditions for each season in Beijing from 2008 to 2014, a U-shaped relationship was found between the daily maximum wind speed and the daily PM concentration, including both PM2.5 and PM10. That is, the relationship between wind speed and PM concentration is not a simple positive or negative correlation in these wind directions; their relationship has a complex effect, with higher PM at low and high wind than for moderate winds. Additionally, in contrast to previous studies, we found that the PM2.5/PM10 ratio is proportional to the mean relative humidity （MRH）. According to this relationship, for each season we established a multiple nonlinear regression （MNLR） model to estimate the PM2.5 concentrations of the missing periods.展开更多
Black carbon （BC） aerosol mass carried by winds of varying directions from non-local sources was esti- mated based on hourly measured data of BC mass concentration （CBc） and meteorological parameters from January ...Black carbon （BC） aerosol mass carried by winds of varying directions from non-local sources was esti- mated based on hourly measured data of BC mass concentration （CBc） and meteorological parameters from January 2008 to December 2012 in Shanghai, and the relationship between annual average CBc and wind speed was analyzed. The results show that the annual average CBC decreased with wind speed for speeds exceeding 0.3 m/s. The relationship between the two was determined by a linear fit with corre- lation coefficient 0,88. Assuming BC aerosol mass of non-local sources transported by a southeast wind was zero, annual average BC concentrations （μg/m3） carried by winds of variable direction were 1.99 （southwest）, 1.95 （west）, 1.15 （northwest）, 0.54 （south）, 0.39 （north）, 0.01 （northeast）, and 0.01 （east）. BC aerosol mass of non-local sources transported by wind to Shanghai was about 6404.05 t per year, among which the total contribution of southwest, west, and northwest winds was nearly 84~;. The aerosol mass transported to Shanghai in winter accounted for 35% that of the entire year, and was greater than that of the other seasons.展开更多
基金supported by the National Science & Technology Major Program of China (No. 2012CB955503)the National Natural Science Foundation of China (Nos. 41421001+1 种基金 41301425 41271404)
文摘When investigating the impact of air pollution on health, particulate matter less than 2.5μm in aerodynamic diameter （PM2.5） is considered more harrnful than particulates of other sizes. Therefore, studies of PM2.5 have attracted more attention. Beijing, the capital of China, is notorious for its serious air pollution problem, an issue which has been of great concern to the residents, government, and related institutes for decades. However, in China, significantly less time has been devoted to observing PM2.5 than for PM10. Especially before 2013, the density of the PM2.5 ground observation network was relatively low, and the distribution of observation stations was uneven. One solution is to estimate PM2.5 concentrations from the existing data on PM10. In the present study, by analyzing the relationship between the concentrations of PM2.5 and PM10, and the meteorological conditions for each season in Beijing from 2008 to 2014, a U-shaped relationship was found between the daily maximum wind speed and the daily PM concentration, including both PM2.5 and PM10. That is, the relationship between wind speed and PM concentration is not a simple positive or negative correlation in these wind directions; their relationship has a complex effect, with higher PM at low and high wind than for moderate winds. Additionally, in contrast to previous studies, we found that the PM2.5/PM10 ratio is proportional to the mean relative humidity （MRH）. According to this relationship, for each season we established a multiple nonlinear regression （MNLR） model to estimate the PM2.5 concentrations of the missing periods.
基金supported by the National Natural Science Foundation of China(No.41275157)Chinese Universities Scientific Fund(CUSF-DH-D-2014048)
文摘Black carbon （BC） aerosol mass carried by winds of varying directions from non-local sources was esti- mated based on hourly measured data of BC mass concentration （CBc） and meteorological parameters from January 2008 to December 2012 in Shanghai, and the relationship between annual average CBc and wind speed was analyzed. The results show that the annual average CBC decreased with wind speed for speeds exceeding 0.3 m/s. The relationship between the two was determined by a linear fit with corre- lation coefficient 0,88. Assuming BC aerosol mass of non-local sources transported by a southeast wind was zero, annual average BC concentrations （μg/m3） carried by winds of variable direction were 1.99 （southwest）, 1.95 （west）, 1.15 （northwest）, 0.54 （south）, 0.39 （north）, 0.01 （northeast）, and 0.01 （east）. BC aerosol mass of non-local sources transported by wind to Shanghai was about 6404.05 t per year, among which the total contribution of southwest, west, and northwest winds was nearly 84~;. The aerosol mass transported to Shanghai in winter accounted for 35% that of the entire year, and was greater than that of the other seasons.
