Analysis of Some Heavy Metals in Grass (<i>Paspalum Orbiculare</i>) and Soil Samples Along Major Highways in Kano.

Abstract

The increased deposition of trace metals from vehicle exhausts on plants has raised concerns about the risks of the quality of food consumed by humans since the heavy metals emitted through the exhaust by vehicles can enter food chain through deposition on grass grazed by animals. Grass (Paspalum Orbiculare) and soil samples were collected from four major highways in Kano, at distance interval of 1,2,3,4 and 5 meters away from the edge of the road. The samples were analyzed for Cd, Fe and Pb using Atomic Absorption Spectrophotometer (AAS). The levels of Fe, Pb and Cd in grass were found to be 5.80±3.11 – 12.60±5.53μg/g, 8.60±4.16 – 12.00±8.19μg/g and 0.12±0.06 – 0.19±0.07μg/g dry weight respectively. The ranges of concentrations in soil were from 5.40±2.51 – 8.20±4.66μg/g, 7.80±3.96 – 13.80±4.60μg/g and 0.18±0.08.25±0.08μg/g dry weight for Fe, Pb and Cd respectively. Heavy metals in the four major roads were significantly higher (P < 0.05) than those on the reference site. The results showed that the levels of Cd and Pb exceeded the limit levels (0.01 – 0.03μg/g for Cd, <7.00μg/g for Pb) and signifies that metal dynamics up the food chain is highly possible.

Keywords: Food chain, Grass, Heavy metals, Paspalum orbiculare, Soil.