This study was conducted to assess particulate matter pollution and the accumulation of airborne toxic metals by studying the foliar deposition pattern in an urban environment. To this end, two commonly growing plants (Senna siamea (Lam.) H.S.Irwin & Barneby and Alstonia scholaris (L.) R.Br.) from the busiest traffic squares of the city (Nehru Chowk) in Bilaspur, India, were selected for detailed study. For this purpose, plant leaf samples of both plant species were collected from pollution-affected areas and a reference site (unpolluted) in the city and examined by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM–EDS) to estimate the accumulation of PM-bound toxic metals at the leaf surfaces. The results of this study showed that the leaves of both plants accumulate PM in different size ranges. Although both plant leaves showed accumulation of PM from respirable suspended particulate matter (RSPM) to ultra-fine particles (UFPs: < 0.1: less than 100 nm) range along with toxic metals, S. siamea retained a higher level of PM than A. scholaris due to better micro-morphological properties on both leaf surfaces. The size of some PM was found to be smaller than the stoma openings. The EDS study proved the presence of harmful airborne toxic metals (Pb, Cd, Cu, Zr, Al, Co, etc.) in these PMs of ambient air. This indicates that toxic metals can enter the leaves through stomatal openings. The results of this study recommended that both plants can be used as a tool to minimise PM pollution.

本研究旨在通过研究城市环境中的叶面沉积模式来评估颗粒物污染和空气中有毒金属的积累。为此，我们从印度比拉斯布尔市（尼赫鲁集市）最繁忙的交通广场中选择了两种常见植物（ Senna siamea (Lam.) HSIrwin & Barneby 和Alstonia selleris (L.) R.Br.）详细研究。为此，从污染影响地区和城市参考地点（未污染）采集了两种植物的植物叶子样本，并通过扫描电子显微镜和能量色散 X 射线光谱（SEM-EDS）进行检查，以估计累积量叶表面与 PM 结合的有毒金属。这项研究的结果表明，两种植物的叶子积累的 PM 大小范围不同。尽管两种植物叶子都显示出从可吸入悬浮颗粒物 (RSPM) 到超细颗粒物（UFP：< 0.1：小于 100 nm）范围内的 PM 以及有毒金属的累积，但S. siamea保留的 PM 水平高于A. siamea。由于两个叶表面具有更好的微形态特性，因此它被称为“scholaris” 。发现一些颗粒物的尺寸小于造口开口。 EDS 研究证明，环境空气中的这些 PM 中存在有害的空气传播有毒金属（Pb、Cd、Cu、Zr、Al、Co 等）。这表明有毒金属可以通过气孔开口进入叶子。这项研究的结果表明，这两种植物都可以用作减少 PM 污染的工具。