稻草和玉米秸秆燃烧烟尘中正构烯烃的组成

在明火燃烧和闷烧条件下对6种稻草和5种玉米秸秆进行了燃烧试验,并对烟尘中的正构烯烃进行了分析.结果表明,在稻草明火烟尘中,正构烯烃由C15~C29组成,其平均总含量为918.7mg/kg,低碳数与高碳数正构烯烃含量比(L/H)的平均值为0.6,碳优势指数(CPI)的平均值为1.2.正构烯烃呈双峰式分布,两个峰碳数主要是C24和C28.在稻草闷烧烟尘中,正构烯烃由C17~C29组成,其总含量、L/H、CPI等的平均值分别是517.0mg/kg、0.7和0.9.正构烯烃同样呈双峰型分布,两个峰碳数主要是C23和C28.在玉米秸秆的明火烟尘中,正构烯烃由C19~C29组成.其总含量、L/H、CPI等的平均值分别为126.0mg/kg、0.7和1.3.正构烯烃呈单峰型分布,主峰碳数主要是C24和C23.在玉米秸秆的闷烧烟尘中,正构烯烃由C17~C29组成,其总含量、L/H、CPI等的平均值分别是198.9mg/kg、1.8和 0.9.正构烯烃呈双峰式分布,其主峰碳数均为C23,次峰碳数主要是C29.在两类秸秆燃烧产生的烟尘之间,正构烯烃的组成存在明显差别.这有助于识别气溶胶中稻草或玉米秆燃烧来源的此类污染物.

Chemical composition of n-alkene in the smoke from rice and maize straw combustion

Straws of six rice genotypes and five maize ones were burned under flaming and smoldering conditions, and n-alkenes in the released smoke were measured. Results showed that, in the flaming smoke for the rice straw, n-alkenes were composed of C15 to C29, and the mean values for the total contents, the ratios of the content for the compounds with low carbon number to that for ones with high carbon number (L/H), and carbon predominance indices (CPI) were 918.7mg/kg, 0.6, and 1.2, respectively. The distribution of the n-alkenes was bimodal with peaks at C24 and C28 in most cases. In smoldering smoke for the straw n-alkenes consisted of C17 to C29, and the average values for the total contents, L/H and CPI were 517.0mg/kg, 0.7and 0.9, respectively. Furthermore, the distribution of the compounds was bimodal with peaks mostly at C23 and C28. In the flaming smoke from maize straw combustion the organic matter was composed of C19 to C29, and the mean values for the total amount, L/H ratios and CPI were 126.0mg/kg, 0.7and 1.3, respectively. Moreover, the distribution type for the compounds was unimodal with a peak at C24 or C23 in most of cases. The n-alkene in smoldering smoke for the straw also consisted of C17 to C29, and the average values for the total contents, L/H ratios and CPI were 198.9mg/kg, 1.8 and 0.9, respectively. In addition, the abundance distribution was bimodal with max peak at C23 and second one mainly at C29. Obvious distinction exists among the chemical composition of n-alkene in the smoke from two straw types under the combustion conditions on all accounts. This has significance in identifying the contaminants from the straw burning in ambient aerosol.