Contribution of flowering trees to urban atmospheric biogenic volatile organic compound emissions
Contribution of flowering trees to urban atmospheric biogenic volatile organic compound emissions
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DOI：
10.5194/bg-9-3777-2012
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发表时间：
2012-01-01
期刊：
影响因子：
4.9
通讯作者：
Daly, R.
中科院分区：
文献类型：
--
作者：
Baghi, R.;Helmig, D.;Daly, R.
2009年春季和初夏在科罗拉多州博尔德市测量了城市树木开花期间和开花后的生物挥发性有机化合物（BVOC）排放量。空气样品收集到固体吸附剂盒从分支外壳上的树种海棠（苹果属），七叶树（Aesculus carnea，“Ft. McNair”）、皂荚（Gleditsia triacanthos，“朝阳”）和山楂（山楂，“Pauls Scarlet”）。这些物种构成类似于65%的昆虫授粉部分的开花树冠（不包括柔荑花序生产树）从博尔德市管理的街道面积。通过热解吸和与火焰离子化检测器和质谱仪（GC/FID/MS）耦合的气相色谱法分析样品的C-10-C-15 BVOC。确定的排放量和排放率从这四个树种在开花阶段被发现在很大范围内变化。确定了皂荚、七叶树和山楂的单萜排放。在七叶树和山楂样品中观察到倍半萜排放。海棠花被发现排放大量的苯甲醇和苯甲醛。花卉BVOC排放量随温度的增加，一般表现出指数温度依赖性。在开花期间和之后的BVOC形态的变化进行了观察，每棵树研究。海棠和皂荚在开花期间的排放速率显著高于开花后的排放速率。将结果按比例缩放到外壳中包含的叶和花的干质量。只有花的干质量占海棠排放速率的叶片出现在开花期结束。总归一化（30摄氏度）的单萜排放从皂荚开花期间（5.3 μ gC g（-1）h（-1））高于开花后（1.2 μ gC g（-1）h（-1））。海棠在开花期间的总标准化BVOC排放率（93 μ gC g（-1）h（-1））与橡树的异戊二烯排放量相同，这是迄今为止从植物中观察到的开花期间植物排放的最高BVOC。这些研究结果表明，在相对短暂的春季开花期，花卉排放构成了迄今为止最显着的贡献，这些树种，其中一些是无叶的在这个时候的BVOC通量。实验结果被集成到MEGAN生物源排放模型和模拟进行估计的贡献，花卉BVOC排放的总城市BVOC通量在春季开花期间。在这三个月的模拟排放的花卉BVOC相当于11%的博尔德市区的综合单萜通量。
Emissions of biogenic volatile organic compounds (BVOC) from urban trees during and after blooming were measured during spring and early summer 2009 in Boulder, Colorado. Air samples were collected onto solid adsorbent cartridges from branch enclosures on the tree species crabapple (Malus sp.), horse chestnut (Aesculus carnea, "Ft. McNair"), honey locust (Gleditsia triacanthos, "Sunburst"), and hawthorn (Crataegus laevigata, "Pauls Scarlet"). These species constitute similar to 65% of the insect-pollinated fraction of the flowering tree canopy (excluding catkin-producing trees) from the street area managed by the City of Boulder. Samples were analyzed for C-10-C-15 BVOC by thermal desorption and gas chromatography coupled to a flame ionization detector and a mass spectrometer (GC/FID/MS). Identified emissions and emission rates from these four tree species during the flowering phase were found to vary over a wide range. Monoterpene emissions were identified for honey locust, horse chestnut and hawthorn. Sesquiterpene emissions were observed in horse chestnut and hawthorn samples. Crabapple flowers were found to emit significant amounts of benzyl alcohol and benzaldehyde. Floral BVOC emissions increased with temperature, generally exhibiting exponential temperature dependence. Changes in BVOC speciation during and after the flowering period were observed for every tree studied. Emission rates were significantly higher during the blooming compared to the post-blooming state for crabapple and honey locust. The results were scaled to the dry mass of leaves and flowers contained in the enclosure. Only flower dry mass was accounted for crabapple emission rates as leaves appeared at the end of the flowering period. Total normalized (30 degrees C) monoterpene emissions from honey locust were higher during flowering (5.3 mu gC g(-1) h(-1)) than after flowering (1.2 mu gC g(-1) h(-1)). The total normalized BVOC emission rate from crabapple (93 mu gC g(-1) h(-1)) during the flowering period is of the same order as isoprene emissions from oak trees, which are among the highest BVOC flowering period floral emissions observed from plants to date. These findings illustrate that during the relatively brief springtime flowering period, floral emissions constitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the total urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11% of the integrated monoterpene flux for the Boulder urban area.