Evaluation of air pollution phytotoxicity in a seasonally dry tropical urban environment.
Jitendra Pandey, Usha Pandey
Author Affiliation: Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221?005, India.
Environmental Monitoring and Assessment 33 : 195-213
Abstract : A study was conducted in the urban environment of Varanasi, India to evaluate plant responses to urban air pollution. Twenty sites were selected in 4 different zones of the city. At each site, plants of the same 7 woody perennials (2 fruit trees - mangoes and guavas; 2 leguminous avenue trees - Delonix regia and Peltophorum pterocarpum; a deciduous timber tree - Dalbergia sissoo; an ornamental shrub - Bougainvillea spectabilis; and a shrub bearing edible berries - Carissa carandas) of the same age classes were selected. Out of the 4 zones (I, II, III and IV), zone IV was used as a reference (control) zone as it received the minimum pollution input. Plant species growing in polluted and control areas were compared with respect to foliar dust load, percentage leaf area injury, leaf area, specific leaf weight and leaf chlorophyll, ascorbic acid, SO42--S and total N concentrations. Results indicated that the air pollution level in Varanasi reduces leaf area and specific leaf weight and leaf chlorophyll, ascorbic acid and total N concentrations. Leaf sulfur concentration increased with increasing levels of SO2 in the ambient air. The magnitude of such changes was greatest at the zone receiving the greatest pollution load. C. carandas was found to be the most sensitive species and B. spectabilis the least. It was concluded that the urban air pollution level in Varanasi is detrimental to the growth of plants used in this study.