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Heavy Metals Concentration in Teak ( Tectona grandis Linn. F.) and Topsoil at Roadside in University of Benin, Benin City, Nigeria
ERAKHRUMEN, AA & INAEDE, S
Abstract
This research was aimed at detecting some heavy metal ions in selected tissues of a standing twenty two
years old Teak (Tectona grandis Linn. F.) trees and the topsoil around them at varied distance from a road within the campus
of University of Benin, Benin City, Nigeria. Concentration levels of seven types of heavy metal ions were evaluated in the
different samples using standard procedures. The results showed that Cu, Cr, Zn, Mn and Fe were detected in the samples
while Cd and Pb were not detected. The concentration of Cu was highest (0.22±0.02μg/g) in leaves at a distance of 5.85m
from the road while it was lowest in bark (0.09±0.01μg/g) and leaves (0.09±0.01μg/g) at a distance of 24.10m from the road.
The concentration of Cr was found to be 0.40±0.03μg/g and 0.40±0.08μg/g in topsoil samples at distance of 5.85m and
18.60m from the road respectively but has a value of 0.17±0.002μg/g in leaves at a distance of 24.10m from the road. It was
also observed that concentration of Zn was 0.93±0.06μg/g in leaves at a distance of 5.85m from the road but was
0.05±0.03μg/g in topsoil at a distance of 24.10m from the road. Additionally, the concentration of Mn was highest in topsoil
(1.10±0.006μg/g) at a distance of 18.60m from the road but was lowest in bark (0.20±0.02μg/g) at a distance of 24.10m from
the road. The concentration of Fe ions was found to be highest in topsoil samples (89.12±0.55μg/g) at a distance of 5.85m
from the road but was lowest in bark (2.07±0.07μg/g) at a distance of 24.10m from the road. The results revealed a somewhat
common trend where concentrations of all the detected heavy metal ions declined in the samples of topsoil and teak’s tissues
as the distance of the locations where the samples were sourced increased from the roadside. The outcomes of this research
appeared to have implicated automobiles as the main source of these pollutants; nevertheless, more intensive scientific
investigations are necessary to provide answers to existing questions concerning ascertaining the source(s) of these pollutants,
if not from petroleum fuelled automobiles, and the possible roles and ability of this tree species, or otherwise, in contributing
to environmental cleaning in the study area.
Keywords
Toxic/noxious substances; Soil pollution; Heavy metal contamination; Phytoremediation
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