包头市大气污染特征及其影响因素

为了解包头市大气污染特征，利用包头市2014年ρ（PM₁₀）、ρ（PM_2.5）、ρ（SO₂）、ρ（NO₂）、ρ（CO）和ρ（O₃）环境空气自动监测数据，结合气象参数，分析了包头市大气污染特征及其影响因素.结果表明:① 包头市春季大气污染以PM₁₀为主，夏季以O₃为主，秋冬两季PM₁₀和PM_2.5均有不同程度污染. ② ρ（PM₁₀）、ρ（PM_2.5）、ρ（SO₂）、ρ（NO₂）的24 h平均值和ρ（O₃）日最大8 h平均值分别有153、76、10、6和3 d超出GB 3095-2012《环境空气质量标准》二级标准限值，ρ（CO）24 h平均值全年达标. ρ（PM₁₀）、ρ（PM_2.5）和ρ（NO₂）年均值分别为GB 3095-2012二级标准限值的2.2、1.6和1.2倍，ρ（SO₂）年均值达标. ③ PM_2.5/PM₁₀（质量浓度比）四季分布为冬季（0.45）>秋季（0.39）>夏季（0.36）>春季（0.27），年均值为0.37，粗颗粒污染特征明显. ④ SO₂/NO₂（质量浓度比）四季分布为冬季（1.76）>春季（1.15）>秋季（0.82）>夏季（0.75），年均值为1.12，并且取暖季明显高于非取暖季，说明冬季燃煤取暖对包头市空气质量有重要影响. ⑤ 包头市的严重污染主要有沙尘型和煤烟型2种. ⑥ 系统聚类分析表明，扬尘引起的PM₁₀对包头市环境空气质量有重要的影响，以SO₂和CO为排放特征的燃煤对PM_2.5有较大的贡献. 

Characteristics of Atmospheric Pollutants and Influencing Factors in Baotou

In order to understand characteristics of atmospheric pollutants in Baotou city, the contents of PM₁₀, PM_2.5, SO₂, NO₂, CO and O₃, as well as the influencing factors were analyzed from data from the automatic air quality monitoring stations. The results showed that:(1) PM₁₀ pollution mainly occurred in spring, while O₃ pollution mainly occurred in summer. PM₁₀ and PM_2.5 caused different extents of pollution in autumn and winter.(2) For concentrations of PM₁₀, PM_2.5, SO₂, NO₂ and O₃, there were 153, 76, 10, 6 and 3 days exceeding the Grade Ⅱ standard of China's National Ambient Air Quality Standard(GB 3095-2012), respectively, while the concentrations of CO were all lower than the standard. The annual concentrations of PM₁₀, PM_2.5 and NO₂ were 2.2, 1.6 and 1.2 times the Grade Ⅱ standard of GB 3095-2012, respectively, while the annual concentration of SO₂ was lower than the standard.(3) The PM_2.5/PM₁₀ ratio in terms of the four seasons followed the order:winter(0.45) > fall(0.39) > summer(0.36) > spring(0.27), with the annual average ratio of 0.37, indicating more coarse particle pollution than fine.(4) The SO₂/NO₂ ratio in terms of the four seasons followed the order:winter(1.76)> autumn(1.15) > spring(0.82) > summer(0.75), with the annual average ratio of 1.12. The ratio of heating season was significantly higher than that of non-heating season, and it showed that the coal combustion in the winter for heating contributed to air quality as a decisive role.(5) There were two main types of severe pollution in Baotou, including the type of dust and a type of soot.(6) Cluster analysis demonstrated that PM₁₀ caused by dust event had important influence on the air quality in Baotou city, while coal combustion characterized by SO₂ and CO pollution had greater contributions to PM_2.5.