西安城郊采暖季大气污染物浓度特征研究

CHARACTERISTICS OF ATMOSPHERIC POLLUTION IN XI'AN SUBURB DURING HEATING PERIOD

2016年11月—2017年2月在西安市城郊连续观测了NO_2、SO_2、O_3和PM_(2.5)的浓度,利用观测数据分析大气污染物的日变化和周末效应特征,结合不同污染物间的相关性分析结果,初步探讨了污染物间的相互作用机理。结果表明:观测期间NO_2、SO_2、O_3和PM_(2.5)浓度的平均值分别为(39.9±21.0),(77.2±22.8),(37.7±23.5),(192±141)μg/m3。PM2.5污染最为严重,超过国家二级标准的2.56倍。NO_2、SO_2和O_3浓度日变化特征显著,其中NO_2和O_3日变化为单峰型,SO_2日变化为单峰单谷型,PM_(2.5)日变化幅度较小。NO_2和SO_2周末效应较为明显,O_3和PM_(2.5)周末与工作日相差较小。PM_(2.5)浓度与NO_2、SO_2和OX浓度均为显著正相关,表明前体物和大气氧化性对PM_(2.5)浓度有显著影响。

Concentrations of NO2,SO2,O3 and PM2. 5were monitored from November 2016 to February 2017 in Xi＇an suburb for describing temporal distribution of atmospheric pollutants. Diurnal variation and weekend effect characteristics of air pollutants were explored. Besides,reaction mechanism of air pollutants was also investigated combined with the results of correlation analysis. The average concentrations of NO2,SO2,O3 and PM2. 5were（ 39. 9 ± 21. 0）,（ 77. 2 ± 22. 8）,（ 37. 7 ±23. 5） and（ 192 ± 141） μg/m^3,respectively. PM2. 5was the main air pollutant and the average concentration was 2. 56 time higher than the level П in ＂The Ministry of Environmental Protection Guideline＂. There were obvious diurnal variation of NO2,SO2 and O3. There was only one peak of NO2 and O3,however there were one peak and one trough of SO2. There was no obvious diurnal variation of PM2. 5relative to other pollutants. The weekend effect of NO2 and SO2 were remarkable,while the difference of concentrations of O3 and PM2. 5 were unobvious between weekend and weekday. Concentrations of PM2. 5were significantly positively correlated with those of NO2,SO2 and OX,which indicated that precursors and atmospheric oxidation had a significant impact on the concentration of PM2. 5