Measuring the Deposition Velocity of Nitrogen Dioxide on Three Big Trees in Taiwan

台灣地區三種大樹吸收二氧化氮沉降速率之測定

孫岩章(En-Jang Sun) ； 王亞男(Ya-Nan Wang) ； 隋婉君(W. J. Swei)

《環境保護》 32卷1期 (2009/06) Pp. 25-38

https://doi.org/10.30017/EP.200906.0003

摘要

樹木可吸收二氧化氮、臭氧與其他毒性污染物，故木本植物在都市區被視為活體空氣清淨機。環保署基於此目的，進行了一項多種樹木於不同環境與時間下，評估其吸收污染物能力的研究計畫。本研究共測試樟樹、烏心石與印度紫檀等三種樹木吸收二氧化氮之能力。本試驗使用45公升聚丙烯枝條套袋，選定健康枝條包覆套袋，並通入二氧化氮氣體，以二氧化氮偵測器測量濃度，並藉由測量總葉面積與總容積，以換算其沉降速率。結果顯示在夏日早晨時間，樟樹、烏心石與印度紫壇之老株二氧化氮沉降速率分別僅為三年幼株之51%、6%與14%；而三年幼株在夏日早晨之二氧化氮沉降速率分別為0.84 mm/sec、0.54 mm/sec與1.11 mm/sec。由此數據推斷，高度分別為10.5公尺、12.5公尺與14公尺之樟樹、烏心石與印度紫壇，每年分別可在台北吸收約0.13公斤、0.008公斤與0.15公斤的二氧化氮。故建議在篩選用以固定二氧化碳之造林樹種時，應同時考慮移除二氧化氮的能力。

關鍵字

二氧化氮 ； 木本植物 ； 沉降速率 ； 台灣

並列摘要

Tree leaves can uptake nitrogen dioxide (NO2), ozone and other toxic pollutants, thus urban trees are thought as live air cleaners in urban areas. On this purpose that Taiwan EPA initiated a project to evaluate the uptake efficiencies of pollutants by various tree species in various environmental and temporal conditions. Three tree species including camphor tree (Cinnamomum camphora), Formosan michelia (Michelia compressa), and rose wood (Pterocarpus indicus) were tested in this study. A PP plastic bag branch chamber with size of 45 L was designed for measuring the NO2 uptake rates of these trees. The bag branch chamber was used to enclose the whole branch when it was selected. The NO2 gas was immediately introduced into the chamber and simultaneously the NO2 concentration was monitored by a NO2 analyzer. Depletion rates and deposition velocities of NO2 by tree leaves were calculated from the net concentration change over the time, the chamber volume and the leaf areas. Results showed that in summer morning time, the old trees of camphor, Formosan michelia, and rose wood, absorbed NO2 for only 51, 6 and 14% of 3-year-old trees did, respectively. The deposition velocities of NO2 to these 3-year-old trees in summer morning time were 0.84, 0.54, and 1.11 mm/sec, respectively. From theses data, the camphor tree, Formosan michelia, and rose wood, respectively with height of 10.5, 12.5, and 14 m, were estimated to uptake 0.13, 0.008, and 0.15 kg of NO2 per year in Taipei. These results suggest that species with higher uptake rates for air pollutants should be screened and selected in our society so that the reforestation unit can use them to remove more toxic NO2 gas as well as carbon dioxide.

並列關鍵字

Nitrogen dioxide ； urban trees ； deposition velocity ； Taiwan