Morakinyo Tobi Eniolu, Lam Yun Fat
City University of Hong Kong, Kowloon, Hong Kong.
Guy Carpenter Asia-Pacific Climate Impact Centre, City University of Hong Kong, Kowloon, Hong Kong.
Environ Sci Pollut Res Int. 2016 Apr;23(7):6709-22. doi: 10.1007/s11356-015-5839-y. Epub 2015 Dec 9.
Well-positioned and configured vegetation barriers (VBs) have been suggested as one of the green infrastructures that could improve near-road (local) air quality. This is because of their influence on the underlying mechanisms: dispersion and mass removal (by deposition). Some studies have investigated air quality improvement by near-road vegetation barrier using the dispersion-related method while few studies have done the same using the deposition-related method. However, decision making on vegetation barrier's configuration and placement for need-based maximum benefit requires a combined assessment with both methods which are not commonly found in a single study. In the present study, we employed a computational fluid dynamics model, ENVI-met, to evaluate the air quality benefit of near-road vegetation barrier using an integrated dispersion-deposition approach. A technique based on distance between source (road) and point of peak concentration before dwindling concentration downwind begins referred to as "distance to maximum concentration (DMC)" has been proposed to determine optimum position from source and thickness of vegetation barrier for improved dispersion and deposition-based benefit, respectively. Generally, a higher volume of vegetation barrier increases the overall mass removal while it weakens dispersion of pollutant within the same domain. Hence, the benefit of roadside vegetation barrier is need-based and can be expressed as either higher mass deposition or higher mass dispersion. Finally, recommendations on applications of our findings were presented.
位置合适且配置合理的植被屏障（VBs）已被视为能够改善近路（局部）空气质量的绿色基础设施之一。这是因为它们对潜在机制有影响：扩散和质量去除（通过沉降）。一些研究使用与扩散相关的方法研究了近路植被屏障对空气质量的改善，而很少有研究使用与沉降相关的方法进行同样的研究。然而，要基于需求实现最大效益来对植被屏障的配置和位置进行决策，需要结合这两种方法进行评估，而这在单一研究中并不常见。在本研究中，我们使用计算流体动力学模型ENVI-met，采用综合扩散-沉降方法评估近路植被屏障的空气质量效益。提出了一种基于源（道路）与下风方向浓度开始下降之前的峰值浓度点之间距离的技术，称为“到最大浓度的距离（DMC）”，以分别确定植被屏障从源起的最佳位置和厚度，从而提高基于扩散和沉降的效益。一般来说，更大体积的植被屏障会增加总体质量去除量，同时会削弱同一区域内污染物的扩散。因此，路边植被屏障的效益是基于需求的，可以表示为更高的质量沉降或更高的质量扩散。最后，给出了关于我们研究结果应用的建议。
