道路植栽設計對懸浮微粒濃度分布影響之研究

Abstract

在都會區中道路旁的空氣品質一直是個被受討論的議題，交通排放為人行道主要的空氣汙染來源，而道路旁的植栽影響著懸浮微粒的沉降與擴散，這兩個作用已被許多現地測量、風洞實驗、軟體模擬等研究所證實，然而如何透過植栽設計達到較佳的空氣品質則需進一步探討，因此，本研究主要目的係探討在不同街谷高寬比下，道路植栽設計對人行道PM2.5濃度之影響。以臺北市道路為研究地點，基於前人研究，以街谷高寬比、植栽配置、葉面積密度、灌木高度進行植栽配置方案之研擬，利用微氣候環境模擬軟體ENVI-met進行模擬。研究結果顯示，在街谷中主要影響PM2.5濃度的因子為風場，當街谷中的大氣流動不佳時，PM2.5不易擴散，而街谷空間配置喬木易造成氣流阻礙，增加局部PM2.5濃度，然而透過調整喬木葉面積密度，能減緩氣流阻礙的影響，而適當種植灌木則能減少污染濃度的提升，但灌木高度增加卻又造成局部PM2.5濃度上升，因此未來在都市街谷的植栽設計應考慮街道環境、風場與植栽種類，以舒緩人行道交通尖峰的PM2.5濃度。

Air quality of the near-road area has been a subject of discussion. Traffic is the main source of air pollution for the sidewalk, and the near-road plant affects the deposition and dispersion of suspended particulates. These two effects have been confirmed by site measurement, wind tunnel experiment, software simulation and so on. However, how to achieve better air quality through plant design is important. Therefore, the main purpose of this study is to explore the planting design effects on the sidewalk PM2.5 concentration. Study area select a street canyon in Taipei City , the research base on the before study using street canyon aspect ratio, planting desion, LAI and shrub height as a program basis. The simulation was carried out by using the micro-climate simulation software ENVI-met. The results show that in the street canyon mainly affect the PM2.5 concentration factor is the wind field. When the atmospheric flow in the street canyon is not good, PM2.5 is not easy to dispersion, and the trees in the street canyon is easy to cause obstruction of airflow and to enhance the concentration of PM2.5, but by adjusting the LAI, can reduce the impact of airflow obstruction. and appropriate planting shrubs can reduce the pollution concentration, but the increase in shrubs also enhance the PM2.5 concentration, so the future in the city streets Planting design should take into account the street environment, wind field and plant species to retard the traffic effect of PM2.5 concentration.