北京市不同主干道绿地群落对大气PM2.5浓度消减作用的影响

为研究城市道路两侧不同绿化带宽度及不同植物群落配置模式对消减大气中PM2.5浓度的作用，选择北京市四环主干道旁3种典型植物群落配置类型作为试验监测点，对0 m、6 m、16 m、26 m、36 m不同绿带宽度下PM2.5浓度分布与变化进行监测，并对其消减能力进行计算，分析PM2.5浓度变化与道路车流量、绿化带宽度及植物群落配置模式之间的关系。结果表明：（1）PM2.5浓度的日变化与车流量的日变化特征一致，道路绿地空气中PM2.5浓度的日变化呈现双峰单谷型特征，即早晚高、白天低，PM2.5浓度在8：00-10：00的交通早高峰期间增加，而后开始下降，到12：00-14：00左右达到最低值，之后呈持续上升状态，直至晚高峰19：00浓度达一天中的最大值。（2）不同植物群落配置模式对大气中PM2.5浓度的消减作用不同，群落内郁闭度高的多复层结构绿地对PM2.5消减作用优于郁闭度低的单层配置绿地模式；（3）分别对3类空气质量条件下，道路绿地对PM2.5消减作用进行评价。无污染或轻度污染（PM2.5〈100μg·m-3）环境下，绿地对PM2.5消减作用明显，26 m及36 m的绿带处消减作用最强，最高可达12.22%；中度污染（101μg·m-3201μg·m-3）天气条件下3种绿地对PM2.5的消减作用均不明显。

Subduction effect of urban arteries green space on atmospheric concentration of PM2.5 in Beijing

Through selecting road green spaces, which communities in the typical configuration, as experimental monitoring points, PM2.5concentration distribution, subduction and its relationship with changes of traffic flow and configuration mode of plant community were studied under different greenbelt widths of 0 m, 6 m, 16 m, 26 m and 36 m. Meanwhile, respectively under three categories of air quality conditions, the effect of road green spaces on PM2.5 abatement were evaluated. The results showed that： 1） Daily changes of PM2.5 concentration were consistent with that of traffic flow, furthermore, diurnal variation characteristics of PM2.5 concentration in road green spaces was described by the double peak and single valley curve, which were high in morning and night and low in daylight, and the highest values at 19：00 and the lowest values at 12：00. 2） The subduction rates were different in green spaces. And the subduction effect of green spaces on PM2.5 concentration, which were more-layer structure types with high canopy density, was better than whose structure types were one-layer with low canopy density. 3） Under the air quality conditions of non-pollution or slight pollution （PM2.5〈100μg·m-3）, the subduction effect of green spaces on PM2.5 concentration was very obvious and greenbelt width of 26 m and 36 m had the best subduction effect by 12.22%. Under the air quality conditions of moderate pollution （101μg·m-3200μg·m-3）, the subduction effect was limited.