| With the accelerating process of urbanization, industrial and transportation energy consumption continues to increase. A large number of emissions lead to the decline in air quality. Air pollution is worsening and then seriously affected the normal production and life of human beings, and has attracted widespread concerns over the world. In this paper, we analyzed the spatial and temporal variation of each pollutant concentration and its relationship with meteorological conditions in Hangzhou using the data of atmospheric pollutant concentration and meteorological data of 2012 to 2014 provided by automatic air quality monitoring stations, discussed the sources and transportation process of atmospheric pollution combining with HYSPLIT model. The main results are as follows:(1) During the experiment in 2014, PM2.5 was in the most serious condition in the urban area of Hangzhou, followed by PM10 and O3, and NO2 was lighter. However, the SO2 and CO were reached the secondary standard value of National Ambient Air Quality Standard.(2) The concentrations of PM2.5, PM10, SO2 and CO displayed a noticeable seasonal variation which are higher in winter and lower in summer, but the seasonal variation of O3 concentrations is opposite. The Ox concentration was lower in summer but maintained higher level in spring, summer and autumn. The NO2 concentration was lower in summer, but maintained higher level in spring, autumn and winter, the pollution concentration in winter was 20μg·m-3 more than that in summer.(3) The highest daily average concentration of NO2 and O3 appeared on Thursday. The NO2 and O3 concentrations on weekdays were slightly higher than that at weekends, but there was no significant difference in concentration between workdays and weekends.(4) The diurnal variations of O3, Ox and SO2 are all in unimodal pattern and the diurnal variations of NO2, CO, PM2.5 and PM10 showed a double peaks distribution whose peaks appeared in rush hours in morning and evening.(5)In the winters of 2012-2014, the hourly and daily average concentrations of SO2 and CO did not reach the secondary standard value of National Ambient Air Quality Standard, the daily average concentrations of NO2, PM2.5 and PM10 are to some extent beyond the standard and those exceeding standard rates were almost the same.(6) Besides CO, the concentration of each pollutant was higher in eastern areas than those in western areas in Hangzhou city, and the concentration peak areas concentrated in the Xiaoshan and its bordering areas. The CO concentration was higher in the southeastern of Tonglu, Jiande and Fuyang, but was lower in the Chun’an. Xiaoshan and Yuhang are the most serious areas of PM2.5 and PM10 pollution in Hangzhou city.(7) The concentrations of different atmospheric pollutants and meteorological factors showed different correlation, and the correlations between pollutants concentrations and meteorological factors varied in different regions of Hangzhou. Wind speed was beneficial to pollutant diffusion obviously in the high pollutant concentration area, however its effect were not so obvious in low pollutant concentration area. When the precipitation reaches a certain amount, the pollutant can be removed obviously, but can’t be greatly reduced by dilution when the precipitation is small.(8) The analysis of influencing factors of atmospheric pollutant concentration in the urban area of Hangzhou and the backward trajectory simulation results of a typical air pollution process showed that continuous east airflow is easy to cause accumulation of pollutants in the urban area of Hangzhou, while northwest airflow and precipitation were beneficial to the diffusion and removal of pollutants. |
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