| 稻草烟尘中正构烷烃和正构脂肪酸的碳同位素 |
| 摘要点击 1973 全文点击 1034 投稿时间：2012-02-19 修订日期：2012-04-04 |
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| 中文关键词 稻草 烟尘 正构烷烃 正构脂肪酸 碳同位素 |
| 英文关键词 rice straw smoke n-alkane n-alkanoic acid carbon isotope |
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| 中文摘要 |
| 为了查清稻草燃烧烟尘中正构烷烃和正构脂肪酸的碳同位素分馏状况,对我国的6种稻草在明火燃烧和闷烧条件下进行室内模拟试验,并测定了烟尘中两类有机物的单体碳同位素. 结果表明,在明火烟尘中,正构烷烃和正构脂肪酸单体的 δ13C值分别为-28.6‰~-38.8‰、-29.6‰~-41.9‰; 正构烷烃和正构脂肪酸的平均碳同位素组成分别是-32.6‰~-36.4‰、-34.0‰~-36.2‰. 在多数稻草的明火烟尘中,正构烷烃 总体上比秸秆内同碳数烷烃亏损13C,其δ13C值最大相差4.1‰. 大部分正构脂肪酸的单体碳同位素组成比稻草重,二者最大相差6.3‰. 在闷烧烟尘中,正构烷烃和正构脂肪酸的单体 δ13C值分别为-31.7‰~-39.0‰、-31.3‰~-38.8‰; 正构烷烃和正构脂肪酸的平均 碳同位素组成分别为-35.1‰~-36.4‰、-34.4‰~-35.6‰. 在多数稻草的闷烧烟尘中, 正构烷烃的单体碳同位素组成比稻草轻,二者最大相差6.1‰; 而正构脂肪酸的单体碳同位素却比稻草重,二者最大相差8.4‰. 稻草闷烧时排放的正构烷烃比明火燃烧时排放的更趋向于亏损13C,而高碳数(≥C19)正构脂肪酸的单体 碳同位素组成呈现出比明火烟尘偏重的趋势. 在稻草烟尘中,正构烷烃和正构脂肪酸的单体碳同位素组成与未燃烧稻草中的对应化合物有显著差别. 烟尘中两类有机物相对于稻草而发生了方向相反的碳同位素分馏. |
| 英文摘要 |
| In order to investigate the carbon isotopic fractionation in n-alkanes and n-alkanoic acids in smoke from rice straw combustion, six types of rice straw were burned in laboratory under flaming and smoldering conditions, and the compound specific isotopic compositions for the two classes of biomarkers in the smoke were determined. The results showed that the δ13C values of individual n-alkanes and n-alkanoic acids released from flaming burns of all the rice species ranged from -28.6‰ to -38.8‰ and from -29.6‰ to -41.9‰, respectively, and that the mean δ13C values for the two compound classes in the flaming smoke for the six types of rice straw were in the range of -32.6‰ to -36.4‰ and -34.0‰ to -36.2‰, respectively. Moreover, the n-alkanes in the smoke from the most straws were more depleted in 13C in general than the identical substances with equal carbon number in corresponding unburned biomass. The magnitude of the isotopic discrimination (Δ) was up to 4.1‰. Conversely, the n-alkanoic acids in the smoke tended to be more enriched in 13C than the corresponding biomarkers in the unburned straw for all of the species, and the Δ was up to 6.3‰. The δ13C values of the individual n-alkanes and n-alkanoic acids in the smoke from smoldering burns of the six species varied between -31.7‰ and -39.0‰ and between -31.3‰ and -38.8‰, respectively. The average values for the two compound classes in the smoke for a species were in the range of -35.1‰ to -36.4‰ and -34.4‰ to -35.6‰, respectively. The compound specific δ13C values of the n-alkanes in the smoke for most species were smaller than those of the same substances in the corresponding rice straw, and the greatest Δ was 6.1‰. However, the δ13C values of n-alkanoic acids in the smoke were greater than those in the rice straw, and the Δ was up to 8.4‰. The n-alkanes from the smoldering burn were more depleted in 13C than those from the flaming burn of the identical rice species, whereas the n-alkanoic acids (≥C19) more enriched in 13C. These results suggest that there is significant difference in the carbon isotopic composition of individual n-alkanes or n-alkanoic acids in the smoke derived from rice straw combustion and the unburned biomass, and that converse carbon isotopic fractionation occurs in the two compound classes in the smoke relative to those in the rice straw. |
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