Padhy P K, Varshney C K
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India.
Environ Pollut. 2005 May;135(1):101-9. doi: 10.1016/j.envpol.2004.10.003.
Foliar emission of isoprene was measured in nine commonly growing tree species of Delhi, India. Dynamic flow enclosure technique was used and gas samples were collected onto Tenax-GC/Carboseive cartridges, which were then attached to the sample injection system in the gas chromatograph (GC). Eluting compounds were analysed using a flame ionisation detector (FID). Out of the nine tree species, isoprene emission was found in six species (Eucalyptus sp., Ficus benghalensis, Ficus religiosa, Mangifera indica, Melia azedarach, and Syzygium jambolanum), whereas, in the remaining three tree species (Alstonia scholaris, Azadirachta indica, and Cassia fistula) no isoprene emission was detected or the levels of emission were negligible or below the detection limit (BDL). Among six tree species, the highest hourly emission (10.2 +/- 6.8 microg g(-1) leaf dry weight, average of five seasons) was observed in Ficus religiosa, while minimum emission was from Melia azedarach (2.2 +/- 4.9 microg g(-1) leaf dry weight, average of five seasons). Isoprene emission (average of six species), over five seasons, was found to vary between 3.9 and 8.5 microg g(-1) leaf dry weight during the rainy season. In addition, significant diurnal variation in isoprene emission was observed in each species. The preliminary estimate made in this study on the annual biogenic VOC emission from India may probably be the first of its kind from this part of the world.
在印度德里常见的9种树木中测量了异戊二烯的叶面排放。采用动态流动密闭技术，将气体样品采集到Tenax-GC/Carboseive滤筒上，然后将滤筒连接到气相色谱仪（GC）的样品进样系统。使用火焰离子化检测器（FID）分析洗脱化合物。在这9种树木中，有6种树木（桉树、孟加拉榕、菩提树、芒果、楝树和蒲桃）检测到异戊二烯排放，而其余3种树木（鸡骨常山、印楝和决明）未检测到异戊二烯排放，或排放水平可忽略不计或低于检测限（BDL）。在6种树木中，菩提树的每小时最高排放量（10.2±6.8微克/克叶干重，五个季节的平均值），而楝树的排放量最低（2.2±4.9微克/克叶干重，五个季节的平均值）。在雨季，5个季节中6种树木的异戊二烯排放（平均值）在3.9至8.5微克/克叶干重之间变化。此外，在每个树种中都观察到异戊二烯排放有显著的昼夜变化。本研究对印度年度生物源挥发性有机化合物排放的初步估计可能是世界上这一地区的首例此类估计。
