Abstract

The increase in the deposition of trace metals as pollutants from vehicle exhausts on plants has raised concerns about the risks for the quality of food and in turn human health. Trace metals emitted by vehicles can enter food chain through deposition on grass growing by the road sides and grazed on by animals. Despite, many investigations knowledge on their spatial distribution near roads is scarce. The concentration of trace metals deposited on roadside Bahama grass, Cynodon dactylon, on roadside grass with over 70,000 vehicles per day were assessed. The spatial distribution of these metal deposits from vehicle emissions during the dry season was assessed by harvesting the grass at 1, 2, 3, 4 and 5 m away from the road. This method allowed an overview of deposition from vehicle emissions. Our results demonstrated the effect of pollution by comparing the levels on both grass and soil sampled. The pollution maps showed that the maximum deposition occurred near the road. The highest pollution levels of grasses were 625 µg/g iron in grass and 120.72 µg/g in soil dry weight. The results were recorded between 1 and 5 m on both sides of the roads. Pollution maps may hence be used to assess the impact of road traffic.

Key words: Pollution, Bahama grass, roadside trace metals.