Cd, Ni, and Pb distribution and pollution assessment in roadside dust from Baghdad City and Western Iraqi Desert

Roadside dust samples were collected from selected areas near the fuel stations in Karkh District of Baghdad City, the capital of Iraq, as well as both sides of the highway between Ramadi and Rutba. In order to assess the probable pollution level of heavy metals (Cd, Ni, and Pb) in the study areas, they were determined in the roadside dust using an atomic absorption spectrophotometer. The extent of traffic contribution to roadside dust was assessed by comparing the metal concentrations in roadside dust to those of Upper Continental Crust background considering a Cd background of 0.098 mg/km, Ni background of 44 mg/km, and Pb background of 16 mg/km using geo-accumulation index (I-geo), contamination factor (CF), and pollution load index (PLI). The roadside dust contains relatively elevated levels of heavy metals. The average concentration of Cd, Ni, and Pb in Baghdad is 0.17, 25.5, and 14.8 mg/kg; in the north of the highway is 0.14, 23.4, and 14.7 mg/kg; and in the south of the highway is 0.2, 27.4, and 15.6 mg/km. The higher averages of these metals were recorded in the south of the highway. The study areas are impacted with considerable quantity of metals. The distribution pattern of the concentrations of metals was essentially affected by exhausted gases emitted from transportation automobile where the direction of the prevailing wind played a major role in the transport of the pollutants, causing an increase in metal concentrations towards the south side of the highway.