WMO区域本底站气溶胶特征分析*

文章通过2002年8月12~27日和2003年7月20日~8月1日在浙江临安县的WMO区域空气污染本底站临安站所采集的气溶胶样品的质量浓度,水溶性离子,有机碳/元素碳(OC/EC)及部分化学元素的特征分析,并与1991年夏季(8月22~28日)气溶胶的某些特征比较,初步研究结果为:1991年至2003年夏季的气溶胶TSP,PM11和PM2.1浓度均呈现出减少的趋势,但是PM11/TSP和PM2.1/PM11则有增加的趋势。1991年、2002年和2003年PM11/TSP的值为90 % 左右,PM2.1/PM11 分别为46.52 % , 69.33 % 和72.29 % ,说明气溶胶以小粒子为主,小粒子又以细粒子为主。1991年、2002年和2003年浓度最高的离子为SO^2-₄,其次为NH^＋₄。其中SO^2-₄占所测离子浓度的百分数分别为65.39 % ,57.75 % 和57.27 % ,并且主要以(NH₄)₂SO₄,(K)₂SO₄和(Na)₂SO₄的形式存在。各离子浓度占所测离子浓度的百分数基本上不随年代变化,具有一定稳定性。2002年和2003年气溶胶中的OC浓度分别为29.91μg/m³和14.14μg/m³,均为各自的组分之首。2002年和2003年OC的比值PM2.1/PM11分别为64.63 % 和77.71 % ,EC的比值PM2.1/PM11分别为69.89 % 和87.17 % ,可见气溶胶中OC和EC主要存在于PM2.1的粒子中。元素富集因子分析表明,自然源与人为源对气溶胶中的元素都有重要的贡献。主因子分析结果显示PM2.1和PM11元素源基本相同,自然源主要是地壳、土壤尘和海盐, 人为源主要是煤飞灰(煤和焦碳)、冶炼工业和道路机动车辆的排放、废物处理、垃圾焚烧及建筑工业粉尘等。

AEROSOL PROPERTIES AT LIN'AN WMO BACKGROUND STATION

Mass concentrations and properties of water-soluble ions, organic carbon/element carbon (OC/EC) and some other elements have been investigated on aerosol samples collected at the WMO Lin'an Atmosphere Pollution Background Station in Zhejiang Province, China during two periods from Aug.12 to 27, 2002 and from July 20 to Aug. 1, 2003. Results of this investigation were compared with those of another period from Aug. 22 to 28, 1991. Summer aerosol mass concentrations measured with TSP, PM11 and PM2.1 were trending to decrease from 1991 to 2003, while values of PM11/TSP and PM2.1/PM11 were trending to increase. Values of PM11/TSP were nearly 90 ％ and those of PM2.1/PM11 were 46.52 ％ , 69.33 ％ , and 72.29 ％ , which suggest that aerosols consists mainly of small particles, especially fine particles. Of all three periods the concentration of SO^2-₄ is the highest with that of NH^＋₄ followed. The SO^2-₄ concentration proportions to total ion concentration is 65.39 ％ , 57.75 ％ , and 57.27 ％ respectively for 1991, 2002 and 2003. The major compounds forming SO^2-₄ are (NH₄)₂SO₄, (K)₂SO₄, and (Na)₂SO₄. The concentration proportion of every ion to total barely changes by year, indicating a stable condition. The concentrations of OC in aerosols of 2002 and 2003 are 29.91μg/m³ and 14.14μg/m³ respectively, which are higher than every component concentration of the corresponding year. The ratios PM2.1/PM11 of OC of 2002 and 2003 are 64.63 ％ and 77.71 ％ respectively, while those of EC are 69.89 ％ and 87.17 ％ , implying that fine particles played the main role in OC and EC. The EF analysis of elements indicate that both the natural emissions and anthropogenic emissions contribute to elements in aerosol. The result of the principal factor analysis demonstrates that the source of elements for PM2.1 and that for PM11 are basically the same. The natural source consists of mainly the crust soil dust and sea salt, while the anthropogenic one consists mainly of ash from coal and coke burning, plus the emission from waste incineration, ferrous and non-ferrous smelter, emission from motor vehicle, and architectural and/or industrial dusts.