Spatial and Temporal Heterogeneity of Metal Contaminants in Soils Along Two Major Roads

The concentrations of zinc, copper, lead and cadmium owing to vehicles were analyzed in roadside soils during all the four seasons from Faisalabad-Gojra road (M-4) and Gojra-Jhang road (GJR) in the Punjab, Pakistan. Results indicated that all the polluted sites along the roadside had comparatively higher metal concentrations as compared to control, nevertheless, spatio-temporal variations in metal concentrations were apparent in different soil samples. The spatial differences in metal concentrations were strongly associated with vehicle density at the Gojra Interchange site and Forest Park site along M-4 and GJR roads, respectively. Among seasons, metal ions exhibited the following order: summer > autumn > spring > winter, indicating that high temperature might have released more metal ions. The metals were recorded in contaminated soil in the order of Zn > Cu > Pb > Cd along both roads. This investigation emphasizes the need for proper environmental management particularly the improvement of roads and proper checking of vehicles running on these regards.