Articles, Conference and Workshop Papers Collection

Permanent URI for this collectionhttp://10.10.97.169:4000/handle/123456789/1790

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Browsing Articles, Conference and Workshop Papers Collection by Subject "Air pollution"

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    Boundary layer perspective assessment of air pollution status in Wuhan city from 2013 to 2017
    (Springer Nature Switzerland, 2019) Mbululo, Yassin; Qin, Jun; Yuan, Zhengxuan; Nyihirani, Fatuma; Zheng, Xiang
    This study used daily air pollution data (PM2.5, PM10, SO2, NO2, CO, and O3) from nine monitoring stations inWuhan city to calculate the air quality index (AQI) from 2013 to 2017. Together with this data, L-band sounding data, ground meteorological data, and air mass back trajectories were also used to describe the dynamics of atmospheric boundary layer (ABL) during pollution process. Analysis of the results shows that, even though the city is still polluted, the number of polluted days was decreasing. Ranking the years in terms of pollution status shows that the year 2013 was the most polluted year while the year 2017 was the cleanest year. Average annual limit of PM10, PM2.5, and NO2 during these 5 years were 1.3~1.8, 1.5~2.7, and 1.2~1.5 times higher than the annual average acceptable limit, respectively. The average ratio of PM2.5/ PM10 for 5 years was 0.67 which signifies that a significant portion of PM2.5 accounted for the total mass of PM10. Moreover, the condition of ABL during the pollution process shows the dominance of strong ground inversion and weak to calm winds. These conditions are not favorable for horizontal and vertical mixing of air pollutants and prevent dilution of pollutants with clean air. Mean cluster analysis of air mass back trajectory shows that pollutants of local origin were more important than the trans-boundary movement of air pollutants. This indicates that the observed pollution in Wuhan was more of local origin
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    Evolution of atmospheric boundary layer structure and its relationship with air quality in Wuhan, China
    (Springer, 2017) Mbululo, Yassin; Qin, Jun; Yuan, Zheng X
    Air pollution data, air quality index (AQI) data and L band sounding data of Wuhan City from January 1 to February 28, 2015, were used in this study. Since air quality is mainly determined by the condition of the atmospheric boundary layer structure (ABLS), a detailed analysis was carried out in order to determine the evolution of this layer and its relationship with air quality. During the investigation period, the highest value of AQI was 307 on January 26 and the lowest was 33 on February 28 indicating ‘severe pollution’ and ‘excellent’ air quality, respec tively. The concentrations of PM2.5 during the days with the highest and lowest AQI were 142.61 and 9.78 μg/m3 , respec tively. The percentage of days in which the ratio of PM2.5 in PM10 was more than half was 83.05% which means that the greater portion of pollutants were composed of smaller particles. Moreover, four PM2.5 episodes (three or more consecutive days of PM2.5 ≥ 75 μg/m3 ) were identified and the average percentage of elementary carbon (EC) in PM2.5 during episode 1 (prior to the episode) was 6.274% (6.276%), episode 2 was 5.634% (7.174%), and episode 4 was 4.067% (7.785%). Higher concen trations of EC prior to episodes suggest biomass burning to be one of the reasons for episodes occurrence. Analysis of the ABLS during polluted days show that the boundary layer was dry and warm and had weak low-level wind and dominance of northerly winds. A different scenario is seen on clean days as the boundary layer is observed to be wet and cool, and there is dominance of strong winds. Back trajectory analysis results show that polluted days were dominated by air mass from north China while on clean days, the dominant air masses were from East China Sea, Mongolia, and west China.