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在模拟的明火燃烧和闷烧条件下对4种玉米秸秆进行了焚烧试验,用GC/MS和GC/C/IRMS分别测定烟尘中正构脂肪酸的分子与碳同位素组成.结果表明,在明火烟尘中正构脂肪酸由C7~C_(34)组成,其平均总含量为13 895.0 mg·kg-1.其低碳数(≤C_(16))与高碳数(>C_(16))正构脂肪酸的含量比(L/H)平均值为1.1.C_(18)/C_(16)、C_(24)/C_(16)、C_(24)/C_(18)、C_(24)/(C_(22)+C_(26))(CAR)的平均值分别为0.33、0.17、0.50、1.2.正构脂肪酸单体表现出以C_(16)、C_(24)为主、次峰碳数的双峰式分布模式.其碳优势指数(CPI)的平均值为4.5.在闷烧烟尘中正构脂肪酸由C_6~C_(34)组成,其平均总含量为50 183.7 mg·kg-1.L/H、C_(18)/C_(16)、C_(24)/C_(16)、C_(24)/C_(18)、CAR的平均值分别为1.3、0.33、0.20、0.60、1.6.也具有与明火烟尘相同的分布模式.其CPI的平均值为6.1.明火烟尘中C_(14)~C_(26)单体的δ~(13)C平均值在-21.0‰~-24.8‰之间变化,总平均值为-23.5‰.该值与玉米秸秆中对应值之差(Δ~(13)C)达-0.7‰.闷烧烟尘中C_(14)~C_(26)单体δ~(13)C平均值的变化范围为-21.8‰~-25.4‰,总平均值为-23.3‰.其Δ~(13)C值达-0.5‰.与玉米秸秆相比,两种烟尘中正构脂肪酸的分子组成和碳同位素组成均发生了明显的改变.L/H、C_(24)/C_(16)、C_(24)/C_(18)、CAR、δ~(13)C等指标可用于识别大气气溶胶中玉米秸秆燃烧来源的正构脂肪酸.
Four kinds of corn stalks were tested for incineration under simulated open-air combustion and smoldering conditions, and the molecular and carbon isotopic composition of normal fatty acids in soot were determined by GC / MS and GC / C / IRMS respectively. The fatty acids consist of C7 ~ C_ (34) with the average total content of 13 895.0 mg · kg-1. The low carbon number (≤C_ (16)) and the high carbon number The average content ratio (L / H) was 1.1.C 18 / C 16, C 24 / C 16, C 24 / C 18, C 24 / C_ 22) + C_ (26)) (CAR) were 0.33, 0.17, 0.50 and 1.2, respectively.Normal fatty acid monomer showed the main C_ (16) and C_ Peak distribution pattern.The average value of carbon index (CPI) was 4.5.The content of normal fatty acids in smoldering soot consisted of C_6 ~ C_ (34) with the average total content of 50 183.7 mg · kg -1 · L / H , C_ (18) / C_ (16), C_ (24) / C_ (16), C_ (24) / C_ (18) and CAR were respectively 1.3, 0.33, 0.20, 0.60, The same distribution pattern of open flame smoke and dust.The average value of CPI was 6.1.The average value of δ ~ (13) C of C_ (14) ~ C_ (26) monomer in open flame smoke varied from -21.0 ‰ to -24.8 ‰, The overall average is -23 .5 ‰ .The difference between this value and the corresponding value in corn straw (Δ ~ (13) C) was -0.7 ‰. The average value of δ ~ (13) C of C_ (14) ~ C_ (26) With a range of -21.8 ‰ to -25.4 ‰ and a mean of -23.3 ‰ .The Δ 13 C value was -0.5 ‰ .Compared with corn stalk, the molecular composition of n-type fatty acids and carbon The isotopic composition of the aerosols is obviously different from that of the aerosol. The indicators such as L / H, C 24 / C 16, C 24 / C 18, CAR and δ 13 C can be used to identify aerosol Corn stalks are the source of normal fatty acids.