Influence of Tree Leaf Surface Characteristics and Wettability in Heavy Metals Accumulation in Tropical Urban Environment

The urban air pollution is a major environmental concern, particularly in the developing countries and in their major cities. In these cities, plants can play a key role in removing pollutants. This study aims to evaluate how surface characteristics of leaves and wettability influence heavy metals accumulation in two tree species (Jatropha interrigima and Ficus benjamina) growing in urban environments. The sampling were performed at roadsides and Parks. Firstly, leaf heavy metal was quantified and the wettability was determined by drop contact angles (DCA). Secondly, the relationship between leaf metal and wettability was found. The two species showed distinct trends in leaf heavy metal accumulation. During the study, the leaf heavy metals content of J. interrigima, a species with adaxial hairy leaf surfaces, was arithmetically higher than that of F. benjamina, a species with waxy leaf surfaces. The DCA on leaves increased with leaf on the abaxial and abaxial surface for both species which, remained highly-wettable (40° < DCA < 90°). However, the DCA on F. benjamina was higher when compared with those of J. interrigima at roadsides. A significant and positive relationship existed between leaf heavy metals content and DCA surface of leaves of both species.