Heavy metals in road-deposited sediments and pollution indices for different land activities

Abstract

The purpose of this paper is to study how urban areas under different land uses influence the heavy metals concentrations. This evaluation was accomplished by determining the concentrations of heavy metals in road-deposited sediments and then applying various pollution indices. The research problems investigated are: first, to measure the relative heavy metal concentrations found in roadside dust samples collected from residential, commercial, and industrial urban areas; second, correlate the heavy metals concentrations to different land uses; and third, to assess the environmental quality of the selected urban areas by employing various pollution indices. The methods used are: (1) Samples were collected using brushes and dustpans from an area measuring 1 m2 from three different areas in Kuwait which were defined by the EPA according to their activities, (2) Samples were extracted by acid digestion (US EPA 3050B) before analysis by ICP-AES (US EPA 6010B), and (3) For pollution analysis, the following indices were employed geo-accumulation index, ecological risk potential, and the risk index. The findings are first, there was an uneven distribution of heavy metal concentrations, the industrial area samples were higher in copper, lead, and zinc (approximately 4, 5, and 2.5 folds, respectively). Second, most trace elements are positively correlated, with many of them showing strong correlations. Third, the geo-accumulation index showed that the industrial area was classified as highly to extremely polluted due to high levels of Pb. The levels of Cd, Cu, and Zn followed Pb which had class 3 or moderately to highly polluted. Fourth, the risk index was about two folds higher in the industrial area than in other areas and the ecological risk potential for most heavy metals was low, except for Cd and Pb. In conclusion, land use could greatly influence the environmental quality of an area and many heavy metals share common sources.