Molecular characteristics of urban organic aerosols from Nanjing: a case study of A mega-city in China.
Molecular characteristics of urban organic aerosols from Nanjing: a case study of A mega-city in China.
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DOI：
10.1021/es051055
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发表时间：
2005-10
影响因子：
11.4
通讯作者：
Gehui Wang;K. Kawamura
中科院分区：
文献类型：
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作者：
Gehui Wang;K. Kawamura
采用气相色谱-质谱联用技术，对南京市夏季和冬季大气细颗粒物（PM2.5）中90多种有机物进行了分析。检测到的有机化合物被分配到四个排放源（即，植物排放、化石燃料燃烧、生物质燃烧和土壤再悬浮）和二次氧化产物。最丰富的化合物类别是脂肪酸，其次是糖、二羧酸（不包括草酸和丙二酸）和正烷烃，而醇、多元醇/多酸和木质素/甾醇含量较低。这7类化合物的总量在夏季平均为938 ng m（-3），在冬季平均为1301 ng m（-3），分别占颗粒物质量（PM2.5）的0.26-1.96%。在夏季，正构烷烃大大增强了植被排放的最大碳数（Cmax）在C29，而他们主要是由化石燃料燃烧的排放量在C22/ C23在冬季。不饱和脂肪酸的浓度在夏季比冬季低，与夏季不饱和脂肪酸的光氧化增强一致。夏季气溶胶中二羧酸的浓度在白天比夜间高得多，表明白天的光化学生产增加。在夏季，植物排放是有机气溶胶的最重要来源，占总化合物质量（TCM）的33%以上，其次是化石燃料燃烧或二次氧化。相比之下，化石燃料燃烧是冬季有机气溶胶的主要来源，占TCM的51%以上，其次是植物排放和二次氧化产物。糖和木质素热解产物的定量结果进一步表明，生物质燃烧和土壤再悬浮也是城市有机气溶胶的重要来源。
Over 90 organic species have been determined in fine aerosols (PM2.5) collected during the summer and winter in Nanjing, a typical mega-city in China, using gas chromatography-mass spectrometry. The organic compounds detected were apportioned to four emission sources (i.e., plant emission, fossil fuel combustion, biomass burning, and soil resuspension) and secondary oxidation products. The most abundant classes of compounds are fatty acids, followed by sugars, dicarboxylic acids excluding oxalic and malonic acids, and n-alkanes, while alcohols, polyols/polyacids and lignin/sterols are less abundant. Total amounts of the seven classes of compounds were on average 938 ng m(-3) in the summer and 1301 ng m(-3) in the winter, respectively, contributing 0.26-1.96% of particle mass (PM2.5). In the summer, n-alkanes were heavily enhanced by vegetation emissions with a maximum carbon number (Cmax) at C29, whereas they were dominated by emissions from fossil fuels combustion with a Cmax at C22/ C23 in the winter. Concentrations of unsaturated fatty acids were lower in the summer than in the winter, being consistent with enhanced photooxidation of unsaturated fatty acids in the summer. Concentrations of dicarboxylic acids for the summer aerosols were much higher in the daytime than in the nighttime, indicating increased photochemical production in the daytime. In the summer, plant emissions were the most significant source of organic aerosols, contributing more than 33% of total compound mass (TCM), followed by fossil fuel combustion or secondary oxidation. In contrast, fossil fuel combustion was the dominant source of winter organic aerosols, contributing more than 51% of TCM, followed by plant emissions and secondary oxidation products. The quantitative results on sugars and lignin pyrolysis products further suggested that biomass burning and soil resuspension are also significant sources of urban organic aerosols.