Liu Gang, Sun Li-Na, Xu Hui, Li Jiu-Hai, Li Zhong-Ping, Li Li-Wu
Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China.
Lanzhou Center for Oil and Gas Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou 730000, China.
Huan Jing Ke Xue. 2016 Nov 8;37(11):4156-4161. doi: 10.13227/j.hjkx.201603194.
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 -alkanoic acids in them. The results showed that -alkanoic acids in flaming smoke were composed of C to C, with a mean total content of 13895.0 mg·kg. The average ratio values of the content for homologues with lower carbon number (≤C) to that for ones with higher carbon number (>C) (L/H), C/C, C/C, C/C, and C/(C+C) (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 and C, respectively. They had evident even to odd carbon number predominance (mean CPI: 4.5). In smoldering smoke the acids were consisted of C to C, with an average total content of 50183.7 mg·kg. The mean ratios of L/H, C/C, C/C, C/C, 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 C) values for individual -alkanoic acids (C to C) in flaming smoke ranged from -21.0‰ to -24.8‰, the overall average of which was -23.5‰. The difference between mean δ C values of -fatty acids in flaming smoke and the straw ( C) was -0.7‰. In smoldering smoke, the mean δ C values for the compounds varied from -21.8‰ to -25.4‰, with an overall average of -23.3‰. The C value was up to -0.5‰. The molecular and carbon isotopic compositions of -alkanoic acids in smoke were significantly different from those in straw matter. L/H, C/C, C/C, CAR, and δ C might be useful proxies to discriminate the organic pollutants in atmospheric aerosols derived from maize straw combustion.
对四个玉米秸秆品种在明火燃烧和闷烧条件下进行焚烧。采集烟雾样本，通过气相色谱/质谱联用仪（GC/MS）和气相色谱/燃烧/同位素比值质谱联用仪（GC/C/IRMS）进行分析，以确定其中ω-链烷酸的分子组成和稳定碳同位素组成。结果表明，明火燃烧烟雾中的ω-链烷酸由C₁₅至C₃₁组成，平均总含量为13895.0 mg·kg⁻¹。碳数较低（≤C₁₈）的同系物与碳数较高（>C₁₈）的同系物含量的平均比值（L/H）、C₁₅/C₁₇、C₁₇/C₁₉、C₁₉/C₂₁和C₁₈/（C₁₆ + C₂₀）（CAR）分别为1.1、0.33、0.17、0.50和1.2。此外，这些酸呈现出双峰分布，峰值分别在C₁₉和C₂₇处。它们具有明显的偶数碳数优势（平均碳偏好指数：4.5）。在闷烧烟雾中，这些酸由C₁₅至C₃₁组成，平均总含量为50183.7 mg·kg⁻¹。L/H、C₁₅/C₁₇、C₁₇/C₁₉、C₁₉/C₂₁和CAR的平均比值分别为1.3、0.33、0.20、0.60和1.6。此外，同系物的分布模式与明火燃烧烟雾中的相同，且具有偶数碳数优势（平均碳偏好指数 = 6.1）。明火燃烧烟雾中单个ω-链烷酸（C₁₅至C₃₁）的平均碳同位素比值（δ¹³C）值在-21.0‰至-24.8‰之间，总体平均值为-23.5‰。明火燃烧烟雾中ω-脂肪酸的平均δ¹³C值与秸秆的δ¹³C值之差（Δ¹³C）为-0.7‰。在闷烧烟雾中，这些化合物的平均δ¹³C值在-21.8‰至-25.4‰之间，总体平均值为-23.3‰。Δ¹³C值高达-0.5‰。烟雾中ω-链烷酸的分子组成和碳同位素组成与秸秆中的显著不同。L/H、C₁₅/C₁₇、C₁₇/C₁₉、CAR和δ¹³C可能是区分源自玉米秸秆燃烧的大气气溶胶中有机污染物的有用指标。
