Dust particles characterization and innate resistance for Thevetia peruviana in different land-use pattern of urban area

摘要

The present work is an attempt to investigate pollution effect on an ornamental tree species Thevetia peruviana (Pers.) K. Schum. The study was conducted in various green spaces of institutional, industrial, residential and near traffic site representing as different status of air pollution concentration depending on land-use type. The resistance index calculated for selected species had mean value of 14.57 +/- 0.41 observed at study sites. The dust deposition was found in range of 5.14-7.74 mg cm(-2) on foliar surface of 12 cm(2). The examination of leaf structure with scanning electron microscope showed presence of airborne dust particles in coarse and fine sizes with higher deposition found in industrial and residential sites. The epicuticular wax layer on upper surface of foliar was found eroded at industrial and traffic regions. The equivalent diameter of particles was observed to range from 0.45 to 12.71 A mu m in Poisson distributional pattern. The density of number concentration of dust particles was observed 1411 and 3703 in institutional and industrial area deposited on 0.22 mm(2) of foliar surface. The elemental distribution on leaves of Thevetia peruviana has revealed a mixture of carbonaceous and soil matrix elements such as C, O, Al, Na, Si, K and Mg observed in proportion of X-rays counts per second. The whole experiment gave a positive indication for plant species as a tolerant bio-indicator of air pollutants in Delhi. The diverse flora present in city provides an opportunity for reducing harmful concentration of PM10 and PM2.5 and improving quality of air for human health.