College of Resources and Environment, Shanxi Agricultural University, Taigu, Shanxi 030801, China.
College of Resources and Environment, Shanxi Agricultural University, Taigu, Shanxi 030801, China.
Sci Total Environ. 2024 Jan 1;906:167365. doi: 10.1016/j.scitotenv.2023.167365. Epub 2023 Sep 26.
Rainfall plays a crucial role in the removal of particulate matter (PM) from plant leaves, influencing PM retention and the environmental behaviour of harmful substances that accumulate in PM. This study examined the PM retention capacity, particle size distributions, and wash-off rates of leaf surface PM from three common green tree species in northern China during two natural rainfall events (light rain: 8.3 mm; heavy rain: 54.2 mm), to investigate the relationship between the leaf traits, PM retention capacity, and PM wash-off process. Our results found that leaf morphometric characteristics, such as leaf size, length, width, and aspect ratio (length-to-width), had a negative and significant correlations with the PM retention capacity, but had no significant correlation with the leaf surface PM wash-off rate. Smaller leaves with low aspect ratios exhibited greater stability under external disturbances than large leaves with high aspect ratios, resulting in a higher PM retention capacity and lower wash-off rate. Ridges and grooves enhanced the PM retention capacity by increasing the leaf roughness. Rainfall could wash off all particle size ranges of leaf surface PM without altering their mechanical composition. Larger particles were more easily washed off. Euonymus japonicus, with its small leaf size and low aspect ratio, exhibited the highest PM retention capacity. Its curled leaf shape also hindered light rain from washing off leaf surface PM. Forsythia suspensa, with denser grooves and ridges compared with Prunus serrulata, exhibited a rougher leaf surface and higher PM retention capacity. However, this roughness may reduce wettability, making it easier for runoff to form on the leaf surface and dislodge leaf surface PM, resulting in F. suspensa having the highest wash-off rate. Our results highlight the synergy of different leaf traits on PM retention capacity and the PM stability after rainfall.
降雨在从植物叶片去除颗粒物（PM）方面起着至关重要的作用，影响 PM 的保留以及在 PM 中积累的有害物质的环境行为。本研究在两次自然降雨事件（小雨：8.3mm；大雨：54.2mm）期间，研究了中国北方三种常见绿化树种叶片表面 PM 的 PM 保留能力、粒径分布和冲刷率，以探讨叶片特性、PM 保留能力和 PM 冲刷过程之间的关系。研究结果发现，叶片形态特征，如叶片大小、长度、宽度和长宽比（长度与宽度的比值）与 PM 保留能力呈负显著相关，但与叶片表面 PM 冲刷率无显著相关。长宽比较低的较小叶片比长宽比较高的较大叶片在外部干扰下更稳定，导致 PM 保留能力较高而冲刷率较低。脊和槽通过增加叶片粗糙度来提高 PM 保留能力。降雨可以冲刷掉叶片表面 PM 的所有粒径范围，而不会改变其机械组成。较大的颗粒更容易被冲刷掉。叶小且长宽比较低的卫矛具有最高的 PM 保留能力。其卷曲的叶片形状也阻碍了小雨冲刷掉叶片表面 PM。与紫叶李相比，忍冬具有更密集的脊和槽，表现出更粗糙的叶片表面和更高的 PM 保留能力。然而，这种粗糙度可能会降低润湿性，使雨水更容易在叶片表面形成并冲刷掉叶片表面的 PM，从而导致忍冬具有最高的冲刷率。研究结果突出了不同叶片特性对 PM 保留能力和降雨后 PM 稳定性的协同作用。
