沈阳冬夏季可吸入颗粒物浓度及尺度谱分布特征
Concentrations and Size Distributions of Inhalable Particles in Summer and Winter in Shenyang
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摘要: 利用沈阳大气成分监测站颗粒物监测仪 (Grimm 180) 连续测得的夏季 (2006年8月)、冬季 (2006年12月和2007年1月) 可吸入颗粒物的数浓度和质量浓度数据, 分析了沈阳市可吸入颗粒物浓度日变化、谱分布及污染特征, 在此基础上结合沈阳市常规气象资料, 分析了气象要素和颗粒物污染之间的关系。结果表明:沈阳市冬、夏季部分时段可吸入颗粒物浓度存在明显的日变化和日际变化; 谱分布较好地符合Junge分布; 沈阳冬季PM10超标日数占冬季观测总天数的77%, PM2.5超标日数 (按美国EPA日均标准) 占冬季观测总天数的87%, PM10平均数浓度为6668.7个/cm3, 平均质量浓度达252.8μg/m3, 分别是夏季的3.0和2.4倍; 冬、夏季PM2.5/PM10平均质量分数分别为0.647和0.603, PM2.5占可吸入颗粒物总数量的99%以上; 浓度变化在很大程度上受到各种气象要素的影响, 与温度、风速负相关, 与湿度正相关, 降雨、降雪过程使得颗粒物浓度明显降低, 近地层逆温和雾是颗粒物增多的一个重要因素。颗粒物污染对城市能见度影响较大。Abstract: Inhalable particles which refer to particles with aerodynamic diameters less than 10μm are the main pollutants in many cities. They are crucial to human health, visibility of atmosphere and radiation balance, and are also the good bearer of atmospheric chemistry reaction.Some studies about inhalable particles are made in Shenyang, but the studies on the number concentration of the surface layer aerosols and the polluted characteristic are scarce, especially the synchronous observation and research about the number and mass concentration of PM10 and PM2.5 are not enough. Atmospheric component monitoring station of Shenyang has begun to continuously and synchronously monitor the PM10 and PM2.5 with ambient dust monitor (Grimm 180) since July 2006. Based on continuous observations of inhalable particles including number and mass concentration data in the atmosphere in August 2006 (summer), in December 2006, and in January 2007 (winter), data are processed by mathematical statistics to obtain the average hourly, daily and seasonal concentration. In order to reveal pollution characteristics of Inhalable Particles in Shenyang, particle spectrum distribution and variations of concentration are analyzed.In addition, the relations to meteorological factors are investigated. Results show that the diurnal and inter-daily variations of concentration are obvious, and diurnal variations of summer and winter both show the characteristics of single peak and single vale. Peak value in summer is earlier than that in winter, but vale value is later. Number and mass concentrations reach the highest point at about 10:00 in winter, and the lowest point is between 13:00 and 14:00. The spectrum distribution conforms to the Junge distribution well, and the average relative error is 9.4%. Number of days that PM10 and PM2.5 mass concentration is above air quality standards, and is 77% and 87% of total days in winter respectively, and number of days that exceeds third class standard is 43%.The mean number density is 6668.7cm-3, and the mass concentration reaches 252.8μg/m3, 3.0 and 2.4 times of summer respectively. Average mass percentage about PM2.5/PM10 of winter and summer respectively are 0.647 and 0.603, PM2.5 average quantity accounts for over 99%of PM10.Concentration variation has a good connection with wind speed, temperature and relative humidity. The spectrum distribution is different as well as the conditions of the different weather, and the precipitation and snowfall could wipe off aerosol concentration obviously, especially of the high clear rate for the fine particles, and the near ground temperature inversion and fog are important for aerosol increase. The visibility in the city is affected evidently by pollution of the airborne particulate matters.
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Key words:
- Shenyang;
- PM10;
- PM2.5;
- size distributions
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表 1 沈阳冬、夏季PM10和PM2.5日均质量浓度 (单位: μg·m-3) 及数浓度 (单位: cm-3)
Table 1 PM10 and PM2.5 daily mean mass concentration (unit : μ g·m-3) and number concentration (unit:cm-3)
表 2 2006年8月24—27日的天气要素及粗、细粒子浓度
Table 2 Meteorological elements and coarse/ fine particle from Aug 24 to 27, 2006
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