For Figure 8, the levels of pH from Wurukum junction (industrial area) ranged between 6.21 and
7.72; 21.07 and 98.91 µS·cm−1 Conductivity; 0.45% and
4.34% organic carbon and 0.51% and 3.79% organic
matter.
4. Discussion
4.1. Heavy Metals in Roadside Soil Samples
4.1.1. Copper (Cu)
It is known that Cu is an essential element, yet it may be
toxic to both humans and animals when its concentration
exceeds the safe limits, and its concentration in some
human tissues such as thyroid can be changed depending
on the tissue state. The highest Cu concentration of 44.21
µg/g was detected at Wurukum junction (heavy traffic
area), which is located at the major commercial area with
high vehicular activities, while the lowest concentration
of 3.22 µg/g was observed at the Federal lowcost housing
area. The reason for the presence concentrations of Cu in
the roadside soil samples might be due to corrosion of
metallic parts of cars derived from engine wear, thrust
bearing, brushing, and bearing metals [24]. Cu concentrations found in this study are lower than that of dust
samples reported by other literatures such as 80.2 mg/kg
in Karak, Jordan [24], 1902.73 mg/kg in Delhi [25].
Copper exhibited high levels of at a distance of 2 meters
closer to the highway and decreases with distance from
the highway.
The concentrations of copper in all the sampling points’
increases with increased in depth. Copper mobility down
to 15 cm has been detected in roadside soil by [26], while
[27] in their study on roadside soil observedincreased Cu
down to a depth of 160 cm. In the present study, the high
levels of Cu (8.32 to 44.21) were noted down to 6 cm.
This result is in accordance with the findings of [28]. [29]
observed significant Cu levels beyond 10 cm depth