Department of Landscape Architecture, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China.
Department of Landscape Architecture, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China.
Environ Pollut. 2018 Feb;233:315-322. doi: 10.1016/j.envpol.2017.10.073. Epub 2017 Nov 5.
Particulate matter (PM) is one of the most serious environmental problems, exacerbating respiratory and vascular illnesses. Plants have the ability to reduce non-point source PM pollution through retention on leaves and branches. Studies of the dynamic processes of PM retention by plants and the mechanisms influencing this process will help to improve the efficiency of urban greening for PM reduction. We examined dynamic processes of PM retention and the major factors influencing PM retention by six trees with different branch structure characteristics in wind tunnel experiments at three different wind speeds. The results showed that the changes of PM numbers retained by plant leaves over time were complex dynamic processes for which maximum values could exceed minimum values by over 10 times. The average value of PM measured in multiple periods and situations can be considered a reliable indicator of the ability of the plant to retain PM. The dynamic processes were similar for PM and PM. They could be clustered into three groups simulated by continually-rising, inverse U-shaped, and U-shaped polynomial functions, respectively. The processes were the synthetic effect of characteristics such as species, wind speed, period of exposure and their interactions. Continually-rising functions always explained PM retention in species with extremely complex branch structure. Inverse U-shaped processes explained PM retention in species with relatively simple branch structure and gentle wind. The U-shaped processes mainly explained PM retention at high wind speeds and in species with a relatively simple crown. These results indicate that using plants with complex crowns in urban greening and decreasing wind speed in plant communities increases the chance of continually-rising or inverse U-shaped relationships, which have a positive effect in reducing PM pollution.
颗粒物（PM）是最严重的环境问题之一，会加重呼吸道和血管疾病。植物具有通过滞留在叶片和树枝上来减少非点源 PM 污染的能力。研究植物对 PM 的滞留的动态过程以及影响这一过程的机制，有助于提高城市绿化减少 PM 的效率。我们在三个不同的风速下，通过风洞实验，研究了 6 种具有不同树枝结构特征的树木对 PM 的滞留的动态过程和主要影响因素。结果表明，植物叶片上 PM 数量的变化是一个复杂的动态过程，最大值可超过最小值的 10 倍以上。在多个时期和情况下测量的 PM 平均值可以被认为是植物滞留 PM 的能力的可靠指标。PM 和 PM 的动态过程相似，可以分别用不断上升、倒 U 形和 U 形多项式函数模拟聚类。这些过程是物种、风速、暴露时间及其相互作用等特征的综合效应。不断上升的函数总是可以解释具有极其复杂树枝结构的物种对 PM 的滞留。倒 U 形过程解释了具有相对简单树枝结构和温和风速的物种对 PM 的滞留。U 形过程主要解释了高风速和相对简单树冠物种的 PM 滞留。这些结果表明，在城市绿化中使用树冠复杂的植物，并降低植物群落中的风速，可以增加不断上升或倒 U 形关系的机会，这对减少 PM 污染有积极作用。
