Roadside air pollution in a tropical city: physiological and biochemical response from trees

Abstract

Background: The economic growth and social interaction of many developing countries have been enhanced by vehicular transportation. However, this has come with considerable environmental cost. The vehicular emissions of gases such as carbon monoxide (CO), sulphur dioxide (SO 2), nitrogen oxide (NOx) and volatile organic compounds (VOC's) among others are associated with vehicular transportation. The resultant effect can lead to respiratory infections in humans, as well as growth inhibition and death of animals and plants. An investigation was conducted to evaluate the impact of vehicular air pollutants on some selected roadside tree species in the Kumasi Metropolis, Ghana. Ficus platyphylla, Mangifera indica, Polyalthia longifolia and Terminalia catappa, which were abundant and well distributed along the road sides, were selected for the study. Three arterial roads in the Kumasi Metropolis, namely Accra Road (Arterial I), Offinso Road (Arterial II) and Mampong Road (Arterial III), were considered as different traffic volumes experimental sites. The KNUST campus was selected as a control site. Diurnal analysis of CO, NO 2 , SO 2 and VOC was monitored in the sample sites. Three replicates of each tree species were defined at a distance 10 m away from the edge of the road. Physiologically active leaves (20 to 25) from each tree species replicate were harvested for physiological and biochemical determination.