Particulate Collection Potential of Trees as a Means to Improve the Air Quality in Urban Areas in India

The particulate collection potential of tree species in a control and five experimental sites of an urban area in India were studied. Tree species selection was based on their commonness to all the sites, proximity to each location and their abundance in Indian subcontinent. A total of 45 leaf samples for all species in each site were analysed following standard protocols in three seasons (monsoon, post-monsoon and pre-monsoon) during 2015–2016. Out of the twenty one selected trees, eight were deciduous and thirteen evergreen. Particulate collection potential of deciduous trees was 22.6% more than that of evergreen trees. The leaf area showed direct relations, whereas petiole length and internodal distance showed antagonistic relations with particulate accumulation. The average particulate deposit on the leaves of trees of experimental sites (0.500 mg/cm2) was significantly more than that of the control site (0.358 mg/cm2). 80.95% of the species showed higher accumulation in the experimental sites against 19.04% of species in the control site. Distinct seasonality (p < 0.05) was noticed in respect of both parameters. Among the trees, Butea monosperma (1.156 mg/cm2), Tectona grandis (0.995 mg/cm2) and Diospyros melanoxylon (0.766 mg/cm2) had a high particulate deposit capacity with capturing efficiency of 48.44, 41.71 and 32.09%, respectively. On the basis of the study, it is advocated that tree species like B. monosperma, T. grandis and D. melanoxylon should be given top priority to function as barriers of particulate matter.