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

摘要

titleAbstract/titlesectitleBackground/titlepThe 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 (SOsub2/sub), 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. italicFicus platyphylla/italic, italicMangifera indica/italic, italicPolyalthia longifolia/italic and italicTerminalia catappa/italic, 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, NOsub2/sub, SOsub2/sub 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./p/secsectitleResults/titlepThe ambient air quality data showed higher levels at the arterial road sites, which were severely polluted based on air quality index. The biochemical studies revealed reductions in leaf total chlorophyll and leaf extract pH whilst leaf ascorbic acid and relative water contents increased at the arterial road sites./p/secsectitleConclusion/titlepIt was found that the plants’ tolerant response level to vehicular air pollution was in the order italicT/italic. italiccatappa/italic  italicF/italic. italicplatyphylla/italic  italicM/italic. italicindica/italic and italicP/italic. italiclongifolia./italic Based on anticipated performance index, it was revealed that italicM/italic. italicindica/italic, italicF/italic. italicplatyphylla/italic and italicT/italic. italiccatappa/italic might be performing some level of air cleaning functions along the arterial roads. Whilst italicP/italic. italiclongifolia/italic was poor and unsuitable as a pollution sink./p/sec