VITO, Boeretang 200, 2400 Mol, Belgium.
Sci Total Environ. 2015 Nov 1;532:474-83. doi: 10.1016/j.scitotenv.2015.06.032. Epub 2015 Jun 19.
Effects of vegetation on pollutant dispersion receive increased attention in attempts to reduce air pollutant concentration levels in the urban environment. In this study, we examine the influence of vegetation on the concentrations of traffic pollutants in urban street canyons using numerical simulations with the CFD code OpenFOAM. This CFD approach is validated against literature wind tunnel data of traffic pollutant dispersion in street canyons. The impact of trees is simulated for a variety of vegetation types and the full range of approaching wind directions at 15° interval. All these results are combined using meteo statistics, including effects of seasonal leaf loss, to determine the annual average effect of trees in street canyons. This analysis is performed for two pollutants, elemental carbon (EC) and PM10, using background concentrations and emission strengths for the city of Antwerp, Belgium. The results show that due to the presence of trees the annual average pollutant concentrations increase with about 8% (range of 1% to 13%) for EC and with about 1.4% (range of 0.2 to 2.6%) for PM10. The study indicates that this annual effect is considerably smaller than earlier estimates which are generally based on a specific set of governing conditions (1 wind direction, full leafed trees and peak hour traffic emissions).
植被对污染物扩散的影响在试图降低城市环境中空气污染物浓度的过程中受到越来越多的关注。在本研究中，我们使用 CFD 代码 OpenFOAM 对城市街道峡谷中植被对交通污染物浓度的影响进行数值模拟。该 CFD 方法是针对街道峡谷中交通污染物扩散的文献风洞数据进行验证的。模拟了不同植被类型和全方位的来风方向（每隔 15°）对树木的影响。使用气象统计学将所有这些结果结合起来，包括季节性落叶的影响，以确定街道峡谷中树木的年平均影响。对于两种污染物，元素碳 (EC) 和 PM10，使用比利时安特卫普市的背景浓度和排放强度进行了这项分析。结果表明，由于树木的存在，EC 的年平均污染物浓度增加了约 8%（范围为 1%至 13%），PM10 的浓度增加了约 1.4%（范围为 0.2 至 2.6%）。研究表明，这种年际效应远小于早期的估计值，这些估计值通常基于特定的控制条件（1 个风向、满是树叶的树木和高峰时段的交通排放）。
