Seasonal Variations of Soil Heavy Metal Contaminants along Urban Roads: A Case Study from the City of Hail, Saudi Arabia

Assessment of seasonal variations in the concentrations of heavy metals -Pb, Cd, Zn, Ni, Cr, Cu, Co, V and Hg- was carried out along two main roads in Hail city; King Abd El-Aziz and King Fahd roads, during August 2009 and January 2010, to identify possible variations in those concentrations during dry and wet seasons. Concentrations were determined using atomic absorbtion spectrometer. The study found that for the samples collected along King Abd El-Aziz road the mean concentrations of Pb, Cd, Zn, Co, Cr, Ni, Cu, V and Hg were: 89ppm, 5ppm, 197ppm, 37ppm, 126ppm, 104ppm, 53ppm, 90ppm and 4ppm in summer season and 88ppm, 6ppm, 201ppm, 38ppm, 120ppm, 106ppm, 55ppm, 93ppm and 4ppm in winter season, respectively. On the other hand, samples collected along King Fahd road showed a mean concetration of 88ppm, 8ppm, 203ppm, 33ppm, 96ppm, 95ppm, 49ppm, 82ppm and 3ppm in summer season and 94ppm, 8ppm, 207ppm, 42ppm, 98ppm, 98ppm, 50ppm, 83ppm and 3ppm in winter season, respectively. According to the calculated values of the geoaccumulation index, the soils of the study area are moderately contaminated with respect to Cd, uncontaminated to moderately contaminated with respect to Pb, Zn and Hg and uncontaminated with respect to Cu, Cr, Co, Ni and V for both winter and summer seasons.