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| Temporal and spatial distribution characteristics of air pollution index in Xi'an, China |
| Zhu Zhenya, Rao Liangyi, Yu Xinxiao, Ren Xiaobo |
| College of Soil and Water Conservation, Beijing Forestry University,100083, Beijing, China |
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Abstract Based on the daily monitoring data from 13 automatic air monitoring stations during the period of 2010 to 2012 in Xi'an, we analyzed daily, monthly, quarterly, and yearly air pollution indexes in heating and non-heating periods, compared with those in northern cities like Qinhuangdao, and used an exploratory spatial analysis technique ESDA to study spatial autocorrelation and agglomeration effects of air pollution index in Xi忆an. The results showed that, there was a high diurnal variation of air pollution index, and PM10 was the primary pollutant in Xi'an. The air pollution index was larger in January and December, while it was lower in July and August. PM10 index decreased generally to a certain extent over the past three years. The SO2 and NO2 indexes declined in the urban area but increased in other regions. SO2, NO2, and PM10 indexes during the heating period were higher than in non-heating period by 2.01 -2.75, 1.42 -1.82, 1.18 -1.36 times, respectively. The pollution index was high downtown, low in the north, and medium in the south. The air pollution index had a positive spatial correlation, but the spatial correlation was weak. High-high aggregation (HH) and low-low aggregation (LL) were more than low-high aggregation (LH) and high-low aggregation (HL), and differentiation in the level of pollution index occurred. Coincidence of peak values of pollutant indexes suggests that the air quality in Xi'an was jointly affected by SO2, NO2 and PM10.
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Received: 14 October 2013
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