玉米秸秆烟尘中正构脂肪酸的分子与碳同位素组成  

Molecular and Carbon Isotopic Compositions of n-Alkanoic Acids in Smoke from Maize Straw Combustion

作　　者：刘刚[1] 孙丽娜[1] 徐慧[1] 李久海[1] 李中平[2] 李立武[2] 

机构地区：[1]南京信息工程大学江苏省大气环境与装备技术协同创新中心,南京210044 [2]中国科学院地质与地球物理研究所兰州油气资源研究中心,兰州730000

出　　处：《环境科学》2016年第11期4156-4161,共6页Environmental Science

基　　金：国家自然科学基金项目(41073019)

摘　　要：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 cultivars of maize straw were burned under flaming and smoldering conditions. Smoke samples were colleted and analyzed by GC / MS and GC / C / IRMS to determine molecular and stable carbon isotopic compositions of n-alkanoic acids in them. The results showed that n-alkanoic acids in flaming smoke were composed of C7 to C（34）,with a mean total content of 13 895. 0 mg·kg- 1.The average ratio values of the content for homologues with lower carbon number（ ≤C（16）） to that for ones with higher carbon number（ C（16））（ L/H）,C（18）/ C（16）,C（24）/ C（16）,C（24）/ C（18）,and C（24）/（ C（22）＋ C26）（ CAR） were 1. 1,0. 33,0. 17,0. 50,and 1. 2,respectively.Moreover,the acids exhibited a bimodal profile with peaks at C（16） and C（24）,respectively. They had evident even to odd carbon number predominance（ mean CPI： 4. 5）. In smoldering smoke the acids were consisted of C6 to C（34）,with an average total content of 50 183. 7mg·kg- 1. The mean ratios of L / H,C（18）/ C（16）,C（24）/ C（16）,C（24）/ C（18）,and CAR were 1. 3,0. 33,0. 20,0. 60,and 1. 6,respectively. In addition,the homologues had the same distribution pattern as in flaming smoke and even to odd carbon number predominance（ mean CPI = 6. 1）. The mean carbon isotopic ratio（ δ^（13）C） values for individual n-alkanoic acids（ C（14） to C（26）） in flaming smoke ranged from- 21. 0‰ to- 24. 8‰,the overall average of which was- 23. 5‰. The difference between mean δ^13C values of n-fatty acids in flaming smoke and the straw（ Δ^13C） was- 0. 7‰. In smoldering smoke,the mean δ^13C values for the compounds varied from- 21. 8‰ to- 25. 4‰,with an overall average of- 23. 3‰. The Δ^13C value was up to- 0. 5‰. The molecular and carbon isotopic compositions of n-alkanoic acids in smoke were significantly different from those in straw matter. L / H,C（24）/ C（16）,C（24）/ C（18）,CAR,andδ^13C might be useful proxies to discriminate the org

关 键 词：玉米秸 烟尘 正构脂肪酸 分子组成 碳同位素 

分 类 号：X51[环境科学与工程—环境工程]