2017—2020年西安市大气污染物时空变化特征

Spatial and temporal variation characteristics of air pollutants in Xi’an during 2017-2020

摘要:

目的 分析西安市6种常见大气污染物的时空变化特征，为环保部门有针对性的进行防控提供科学依据。方法 以高时间分辨率的大气污染监测数据为基础，对西安市6种常见大气污染物的时空分布特征进行分析，并对各污染物间的相关性进行研究。结果 除O3_8h外，其余5种大气污染物年平均浓度均呈现逐年下降。截至2020年，PM2.5和PM10的年平均浓度仍超过二级浓度限值，NO2的年平均浓度略高于一级浓度限值，O3_8h的未达标天数占全年的十分之一。PM2.5、PM10、CO、SO2、NO2浓度均整体呈现冬季最高、春秋季相当、夏季最低的特征，O3_8h浓度整体呈现夏季>春季>秋季>冬季的特征。2020年9个城区PM2.5和PM10的年平均浓度均超过二级浓度限值，新城区、莲湖区、碑林区、雁塔区NO2的年平均浓度均超过二级浓度限值，莲湖区、碑林区、长安区、阎良区O3_8h的年平均浓度均超过西安市平均水平。PM2.5、PM10、CO、SO2、NO2间整体呈现不同程度的正相关性，夏季O3_8h与其他大气污染物间呈现正相关性，在其他季节则整体呈现负相关性。结论 西安市大气污染情况有逐年向好趋势，但PM2.5、PM10、O3_8h污染仍超标严重，其仍将作为西安市大气污染的长期防治重点。

Abstract:

Objective To analyze the temporal and spatial variation characteristics of six common air pollutants in Xi'an, and to provide a scientific basis for the environmental protection departments to conduct targeted prevention and control. Methods Based on air pollution monitoring data with high temporal resolution, the temporal and spatial distribution characteristics of six common air pollutants in Xi'an were analyzed, and the correlation between the pollutants was studied. Results Except for O3_8h, the annual average concentrations of the other five air pollutants decreased year by year. By 2020, the annual average concentration of PM2.5 and PM10 still exceeded the second-level concentration limit. The annual average concentration of NO2 was slightly higher than the first-level concentration limit, and the number of unqualified days of O3_8h accounted for one-tenth of the entire year. The concentrations of PM2.5, PM10, CO, SO2, and NO2 all were the highest in winter, equivalent in spring and autumn, and the lowest in summer. The concentration of O3_8h generally presented the characteristics of summer > spring > autumn > winter. In 2020, the annual average concentrations of PM2.5 and PM10 in 9 urban areas exceeded the second-level concentration limit. The annual average concentrations of NO2 in Xincheng District, Lianhu District, Beilin District, and Yanta District all exceeded the second-level concentration limit. The annual average concentration of O3_8h in Beilin District, Chang'an District, and Yanliang District all exceeded the average level of Xi'an. PM2.5, PM10, CO, SO2, and NO2 in general showed a positive correlation in varying degrees. In summer, O3_8h showed a positive correlation with other air pollutants, but a negative correlation in other seasons. Conclusion The air pollution situation in Xi'an has been improving year by year, but the pollution of PM2.5, PM10, and O3_8h still exceeds the standard, which will be the focus of long-term prevention and control of air pollution in Xi'an.