城市道路隔离带绿化模式对人行道空气质量的影响评价

探讨城市道路绿化隔离带对于污染物的阻滞效应,以减少城市道路污染向两侧横向扩散,保护道路行人免受来自机动车道污染物的伤害具有重要的现实意义.因此,本研究在太原市区选择16条主干道(28个监测样点),以4种绿化植物配置模式(乔木+灌木+低绿篱、乔木+低绿篱、乔木、低绿篱)为研究对象,在无风或者微风(风速小于2 m·s-1)条件下对SO2、NOx、TSP和PM10等5种污染物进行现场监测.研究结果表明,城市道路绿化隔离带对于控制机动车道的主要污染物向非机动车道的扩散具有明显作用,绿化隔离带的植物模式差异会影响绿化带吸附和阻隔污染物能力的强弱.在此基础上,通过构建一个新的评价指标来比较各个模式在阻滞污染物方面的能力.结果显示,与其他模式相比,低绿篱模式和乔木+灌木+低绿篱模式分别对NH3和PM10具有更高的降低能力.对于SO2、NH3、NOx等气态污染物,以乔木(T)为配置模式的绿化带效果最佳,而对于TSP、PM10等颗粒污染物,乔木+灌木+低绿篱(TSH)模式的阻滞净效应最高.新评价指标能够准确定量评价绿化带植物对污染物阻滞效应能力的大小,具有较好的应用性.

Impact of plant configuration mode of greening segregating belt on air quality of adjacent sidewalk in urban street

Vehicle emissions are key sources of air pollution in most cities of China. The available literature indicates that roadside vegetation has the potential to mitigate vehicle-generated air pollution through increasing deposition rate of particulates and/or absorption of gaseous pollutants, but lacks the information on the impact of different designs on the efficacy. Therefore, it is important to assess critical design factors of greenbelt, especially for practical considerations on road-user(pedestrian, bicycler, etc.) safety. Field monitoring of pollutants concentration(SO₂, NO_x, NH₃, TSP and PM₁₀) in urban street with greenbelt were performed using medium-flow air samplers at 28 sample locations in 16 streets in Taiyuan, China. Plant configuration modes (vegetation structure) were categorized into 4 types: Tree+Shrub+Hedge(TSH), Tree+Hedge(TH), Tree(T) and Hedge(H). It was found that tree planting of four modes all reduced the pollutants concentration of sidewalk air significantly. The decrease in concentration showed a maximum decrease of SO₂, NO_x, NH₃, TSP and PM₁₀ by 31.4%, 23.0%, 35.0%, 38.2% and 39.6% respectively in plots of TSH. There was no difference in reduction rate of SO₂, NO_x and TSP among four modes. Moreover, a new parameter was proposed to accurately compare the efficacy among different modes. In comparison to others, markedly higher efficacy of NH₃ reduction in T mode and PM₁₀ capture in TSH mode were observed. Capture of particulate pollutant (e.g. TSP, PM₁₀) was more efficient with TSH mode by the presence of more leaf area and higher density, and decrease of gaseous contaminant was more effective with T mode due to good ventilation.