| Sulfur dioxide (SO2), nitrogen oxides (NOx), surface ozone (O3) and particulate matter (PM10) are important atmospheric pollutants affecting air quality in cities. Since they play an important role in atmospheric photochemical reactions and their ecological environment effects human health effects, more and more scientists and people are paying close attention to these atmospheric pollutants.Atmospheric pollution in Beijing-Tianjin-Hebei region has obvious compound and regional characteristics, so if local sources of emissions are controled only it will still difficult to improve air quality. With the use of automatic online monitoring analyzer instruments, the continuous observation of typical atmospheric pollutants was done from September2009to August2011in Zhangjiakou, Beijing and Langfang. The inter-annual trends, seasonal and diurnal variation of atmospheric pollutant concentration in Zhangjiakou, Beijing and Langfang have been systematically described, The pollution status during the last two years has also been illuminated, and the issue that the transport and exchange of atmospheric pollutant over the regional cities, with the influence of southerly air masses and northerly air mass, has been discussed, respectively. The main findings are as follows:The primary pollutants in the region was PM10.In the entire observation period, the mean concentration of PM10were reached (133±97)μg·m-3in Beijing,(146±100)μg·m-3in Langfang and (137±105)μg·m-3in Zhangjiakou, and the rate of PM10in Beijing, Langfang and Zhangjiakou exceeded the National Ambient Air Quality Standard Ⅱ was32%,40%and27%, respectively. The mean concentration of NOx were as high as (81±59)μg·m-3in Beijing,(75±56)μg·m-3in Langfang and (37±24)μg·m+3in Zhangjiakou, and the rate of NOx in Beijing, Langfang and Zhangjiakou exceeded the National Ambient Air Quality Standard Ⅱ(NAAQS Ⅱ) was32%,40%and27%, respectively. The concentrations of NOx in Beijing and Langfang exceeded the NAAQS Ⅱ during both autumn and winter. The mean concentration of SO2were as high as (27±33)ug·m-3in Beijing,(30±33)μg·m-3in Langfang and (24±29)μg·m-3in Zhangjiakou, and the concentrations of SO2in all the three cities during both autumn exceeded the NAAQS Ⅱ during the heating period. The mean concentration of O3were as high as (40±30)μg·m-3in Beijing,(49±36)μg·m-3in Langfang and (56±35)μg·m-3in Zhangjiakou, and the pollution of near surface O3was relative concentrated with peaking nearly May and June.The analysis of the diurnal variation of atmospheric pollutant in four seasons shows that: The diurnal variation of NOx had a bimodal, with peaking in early morning and evening, but the evening peak of NOx in Beijing delayed to23:00during autumn and winter time. The concentration of O3showed Single-peak type change characteristics. The diurnal variation of SO2was significantly in winter time, with a bimodal characteristics, while relatively flat during summer time, and peaking at noon in other seasons. The diurnal variation of PM10was similar to NOx in Zhangjiakou and Langfang showing bimodal characteristics, but irregular in Beijing.Air masses from southeast regions in summer could transport O3and its precursors to Zhangjiakou and caused local air pollution accumulation, and the concentration of O3peaked in the middle of the night. Northwesterly air masses which passed Mongolia carried dust and local dust caused by strong winds greatly affected PM10in all three cities, and North China Plain was also affected in some degree. Southerly air masses which passed heavily polluted areas, with small wind speed could easily cause accumulation of pollutants in all three cities. |
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