Spacial Distribution of Soil Pollution along the Main Highways in Hail City, Saudi Arabia

Attention to heavy metal contamination associated with highways has risen in the past decades because of the associated health hazards and risks.The present study analyzed the metal content in soil samples along the main highways in the central part of Hail city.The samples were obtained at two depths, 0-10 cm and 10-20 cm and were analyzed by atomic absorption spectrophotometery for lead, cadmium, copper, cobalt, nickel, cromium, vanadium, mercury and zinc. Physicochemical factors believed to affect the mobility of metals in the soil of the study area were examined such as; pH, TOM, CaCO3, CEC and conductivity. Data were spatially and statistically ivestigated to know the distribution of metals in space.Correlation coefficient analysis and principle component analysis were used to provide a better understanding of heavy metal pollution. This study indicates that all of the metals are concentrated on the surface soil, and decrease in the lower part of the soil, reflecting their mobility and physical properties of the soil and its alkaline pH values. The use of factor analysis showed that anthropogenic activities seem to be the responsible source of pollution for metals in urban soils.The relatively high concentrations of Cd, Pb, Zn,Cr and Cu in the soils of the study area are related to anthropogenic sources mainly from vehicle exhausts.