Beijing Laboratory of Urban and Rural Ecological Environment, Beijing Forestry University, Beijing, China; Department of Atmospheric and Oceanic Sciences, University of Wisconsin, Madison, WI, United States.
Beijing Laboratory of Urban and Rural Ecological Environment, Beijing Forestry University, Beijing, China.
Environ Pollut. 2019 Dec;255(Pt 1):113234. doi: 10.1016/j.envpol.2019.113234. Epub 2019 Sep 11.
The presence of plant leaves has been shown to lower the risks of health problems by reducing atmospheric particulate matter (PM). Leaf PM accumulation capacity will saturate in the absence of runoff. Rainfall is an effective way for PM to "wash off" into the soil and renew leaf PM accumulation. However, little is known about how PM wash-off varies with PM size and health problems caused by particulate pollution vary with PM size. This study thus used artificial rainfall with six plant species to find out how size-fractioned PM are washed off during rain processes. Total wash-off masses in fine, coarse and large fractions were 0.6-10.3 μg/cm, 1.0-18.8 μg/cm and 4.5-60.1 μg/cm respectively. P. orientalis (cypress) and E. japonicus (evergreen broadleaved shrub) had the largest wash-off masses in each fraction during rainfall. P. cerasifera (deciduous broadleaved shrub) had the largest cumulative wash-off rates in each fraction. Rainfall intensity had more influence on wash-off masses and rates of large particles for six species and for small particles in evergreen species, but limited effect on wash-off proportions. Wash-off proportions decreased in large particles and increased in small particles along with rainfall. The results provide information for PM accumulation renewal of plants used for urban greening.
植物叶片的存在可以通过减少大气颗粒物（PM）来降低健康问题的风险。如果没有径流，叶片对 PM 的积累能力就会饱和。降雨是 PM 进入土壤并更新叶片 PM 积累的有效方式。然而，人们对 PM 洗脱量随 PM 大小的变化以及颗粒物污染引起的健康问题随 PM 大小的变化知之甚少。因此，本研究使用人工降雨对六种植物进行了研究，以了解在降雨过程中，大小分级的 PM 是如何被洗脱的。细颗粒、粗颗粒和大颗粒的总洗脱质量分别为 0.6-10.3μg/cm、1.0-18.8μg/cm 和 4.5-60.1μg/cm。在降雨过程中，P. orientalis（柏树）和 E. japonicus（常绿阔叶灌木）在每个部分的洗脱质量最大。P. cerasifera（落叶阔叶灌木）在每个部分的累积洗脱率最大。降雨强度对六种植物的大颗粒和常绿植物的小颗粒的洗脱质量和速率有更大的影响，但对洗脱比例的影响有限。随着降雨的进行，大颗粒的洗脱比例减少，小颗粒的洗脱比例增加。研究结果为城市绿化中使用的植物的 PM 积累更新提供了信息。
