| 贡嘎山本底站大气中VOCs的研究 |
| 摘要点击 2836 全文点击 1441 投稿时间：2012-02-27 修订日期：2012-04-07 |
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| 中文关键词 挥发性有机物 季节变化 PCA受体模型 异戊二烯 贡嘎山本底站 |
| 英文关键词 volatile organic compounds (VOCs) seasonal variation PCA receptor model isoprene Gongga Mountain base station |
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| 中文摘要 |
| 为研究中国西南地区大气中挥发性有机物(VOCs)区域性本底浓度和变化特征,利用不锈钢钢瓶采样、三步冷冻浓缩进样-气相色谱/质谱联用技术(GC/MS),测定了贡嘎山大气本底站大气中的VOCs组成、浓度及季节变化,并利用PCA(principal component analysis)受体模型对大气中VOCs来源进行了初步分析. 结果表明,贡嘎山地区TVOCs和NMHCs的年平均浓度(体积分数)分别为9.40×10-9±4.55×10-9和7.73×10-9±4.43×10-9,且两者的最高和最低浓度都出现在同一次采样. 在TVOCs中,芳香烃所占比例最大,为37.3%,烷烃(30.0%)和卤代烃(19.8%)次之,烯烃的比例最低,为12.9%. 通过PCA受体模型分析发现,贡嘎山地区大气中VOCs的主要来源可以归结为交通源、生物源和燃烧源. 贡嘎山地区大气中TVOCs呈现明显的季节变化,变化特征为秋季>冬季>春季>夏季,秋季和冬季大气中的TVOCs浓度分别极显著(P<0.01)和显著地高于夏季(P<0.05),由于光化学性质的差异, 4种类型的VOCs季节变化也呈现出不同的特征. 异戊二烯是生物源的重要排放物,其排放速率与大气温度呈指数相关,在20℃以上随着温度的升高排放速率明显增强,其最高和最低值分别出现在夏季的下午和冬季的上午. 与其他地区的研究结果相比,贡嘎山地区TVOCs的排放处于中等水平,有着明显的本底站排放特征. |
| 英文摘要 |
| Volatile organic compounds (VOCs) play important roles in the atmosphere as precursors of secondary air pollutants. The regional background concentrations and variation characteristics of VOCs in the atmosphere of southwestern China were studied. Meanwhile, a receptor model based on principal component analysis (PCA) was used to identify the major sources of VOCs. Weekly samples were collected in 2007 in the Gongga Mountain base station and analyzed with a three-stage preconcentration method coupled with GC-MS. The annual mean concentration of TVOCs and NMHCs were 9.40×10-9±4.55×10-9 and 7.73×10-9±4.43×10-9, respectively. Aromatic hydrocarbons provided the largest contribution to TVOCs (37.3%), follow by alkanes (30.0%) and halogenated hydrocarbons (19.8%), the smallest contribution was from alkenes (12.9%). Three major sources were resolved by the receptor model, traffic sources, biogenic sources and combustion sources. The seasonal variation of TVOCs in this area was obviously, and the order was autumn>winter>spring>summer. TVOCs concentration in autumn was very significantly higher than that in summer (P<0.01). The seasonal variation of the four types of VOCs showed different characteristics due to the differences in photochemical properties. Isoprene emissions were from biogenic sources. Regression analysis revealed a good exponential relationship between the isoprene concentration and temperature. High temperatures increased the isoprene concentrations. However, the isoprene concentration remained constant when the ambient air temperature was below 20℃. The TVOCs in Gongga Mountain were at a medium level comparing with the results of other regions, and there was a clear background station emission characteristic. |
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