Heshani A L Savinda, Winijkul Ekbordin
Environmental Engineering and Management, School of Environment, Resources and Development, Asian Institute of Technology, Thailand.
Heliyon. 2022 Aug 31;8(9):e10475. doi: 10.1016/j.heliyon.2022.e10475. eCollection 2022 Sep.
Traffic emission has been identified as one of the dominant sources of fine particulate matter (PM) in Thailand, and urban green spaces have the capacity to mitigate air pollution. Taking Bangkok as the study area, one of the most polluted cities in Thailand, this study investigated the effect of vegetation on PM concentration at three different sites with different vegetation characteristics in Chatuchak Park, an urban park located in Bangkok. Sensors were installed at the park to measure PM and metrological parameters at the roadside and different distances inside the park away from the road, and the ENVI-met model was run to simulate PM concentration in the three study sites. The result shows that PM concentration behind the vegetation barrier was reduced 34% on average compared to the concentration next to the road at the three sites. The effect of vegetation on meteorological factors was clearly seen near the park border with a hedgerow grown along the border. The order of influence of meteorological factors on PM concentration was relative humidity > potential temperature > wind speed > wind direction. Two scenarios including changes in weather patterns and types of vegetation that affect PM concentration were studied. Changing in the wind direction from oblique to perpendicular to the park had no significant effect on PM concentration as long as there is a dense hedgerow along the park border. Comparing to the current vegetation, sparse vegetation with less leaf area density and higher crown base heights had lower impact to mitigate PM concentration in the park. Our study provides information on vegetation and landscape strategies which can provide good air quality in the urban parks for better park design in the future.
交通排放已被确定为泰国细颗粒物（PM）的主要来源之一，而城市绿地具有减轻空气污染的能力。以泰国污染最严重的城市之一曼谷为研究区域，本研究调查了位于曼谷的乍都乍公园内三个具有不同植被特征的不同地点的植被对PM浓度的影响。在公园安装了传感器，以测量路边以及公园内远离道路不同距离处的PM和气象参数，并运行ENVI-met模型来模拟三个研究地点的PM浓度。结果表明，在这三个地点，植被屏障后方的PM浓度与路边浓度相比平均降低了34%。在公园边界附近，沿着边界种植了树篱，植被对气象因素的影响清晰可见。气象因素对PM浓度的影响顺序为相对湿度>位温>风速>风向。研究了两种情景，包括影响PM浓度的天气模式变化和植被类型变化。只要公园边界沿线有茂密的树篱，风向从倾斜变为垂直于公园对PM浓度没有显著影响。与当前植被相比，叶面积密度较小且树冠基部高度较高的稀疏植被对减轻公园内PM浓度的影响较小。我们的研究提供了有关植被和景观策略的信息，可为未来更好地设计城市公园提供良好的空气质量。
