| 北京城区大气PM2.5主要化学组分构成研究 |
| 摘要点击 3431 全文点击 1439 投稿时间：2014-11-24 修订日期：2015-02-15 |
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| 中文关键词 PM2.5 城区 质量重构 化学组分 未知组分 |
| 英文关键词 PM2.5 urban area mass closure chemical species unidentified composition |
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| 中文摘要 |
| 2012年8月至2013年7月期间,对北京市城区石景山、车公庄、东四和通州这4个点位开展为期一年的PM2.5化学组分研究,共获得样本220组,使用化学质量重构方法进行组分重构研究.结果表明,通过化学质量重构方法获得的PM2.5质量和实际测定PM2.5质量浓度具有很好的相关性,相关系数为0.95,其中春季、秋季和冬季相关系数均大于0.95以上, 夏季稍差(0.77); 采样期间4个点位的PM2.5主要组分OM、EC、SO42-、NO3-、NH4+、Cl-、地壳元素、微量元素的质量浓度分别为31.4、3.8、19.9、21.6、14.4、4.0、15.4、2.9 μg ·m-3,分别占总组分的25.1%、3.0%、15.9%、17.2%、11.5%、3.2%、12.3%、2.3%,除地壳物质外各组分呈东高西低的趋势; 2013年1月11日至14日重污染期间, OM、SO42-、NO3-、NH4+的浓度是全年平均的1.9、5.0、3.2、4.2倍, SO42-成为本次污染过程中最主要的组分.采暖期和非采暖期城区PM2.5最大的组分均为OM,采暖期相对非采暖期OM、NH4+、NO3-、SO42-均有较大增幅,但地壳物质和EC相差不大,两个时期差异最大的组分为具有较强燃煤指示性的Cl-(4.4倍). 对于化学质量重构结果的未知组分,其中城区PM2.5中水份约占6.0%, 夏季颗粒物的水份最大(6.5%), 春季和冬季相当, 秋季较少(3.7%). |
| 英文摘要 |
| From August 2012 to July 2013, 220 groups of PM2.5 samples were continuously collected at four locations in the urban area of Beijing (Shijingshan, Chegongzhuang, Dongsi, and Tongzhou), and the primary chemical species of PM2.5 were analysed by the chemical mass balance method. It was found that the mass of PM2.5 obtained from chemical mass balance method agreed well with the value from gravimetric measurement, with a good correlation of 0.95 in spring, autumn, and winter. However, the correlation seasonally changed in summer, with a relatively lower correlation coefficient of 0.77. The concentrations of OM, EC, SO42-, NO3-, NH4+, Cl-, crustal matter, and trace species were 31.4, 3.8, 19.9, 21.6, 14.4, 4.0, 15.4, and 2.9 μg ·m-3, which accounted for 25.1%, 3.0%, 15.9%, 17.2%, 11.5%, 3.2%, 12.3%, and 2.3% of PM2.5, respectively. Besides crustal matter, concentrations of the primary chemical species in PM2.5 from the west to the east gradually increased. The most serious PM pollution occurred between 11 and 14 February 2013, during which concentrations of OM, SO42-, NO3-, NH4+ were 1.9, 5.0, 3.2 and 4.2 times as high as the annual average. SO42- was recognized as the most important species for the pollution in the process. OM was the largest component of urban PM2.5 during both heating and non-heating periods. Comparing to non-heating period, the concentrations of OM, NH4+, NO3-, and SO42- all increased during the heating period, except for the component of crust and EC. The biggest difference between the two periods was the component of Cl-(4.4 fold), which can be attributed to the burning of coal. For unknown components, the main component was moisture, which accounted for about 6.0% in urban PM2.5. The highest moisture appeared in summer (6.5%), followed by spring and winter, and the least appeared in fall (3.7%). |
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