ASSESSMENT OF HEAVY METAL LEVELS IN URBAN SOILS OF TRIPOLI, LIBYA, USING POLLUTION INDICES AND MULTIVARIATE ANALYSIS

This study analysed forty-six soil samples from the top 15 cm (6 in.) of urban soil in Tripoli, Libya for heavy metal contamination using atomic absorption spectrometry. The metals assessed included cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn) and chromium (Cr), with average concentrations of 3.94±1.93, 38.17±11.67, 170.94±62.68, 29.67±8.00, 19.70±8.75, 30.38±10.68, 27.444.52±8,739.15, 233.82±48.24, and 195.92±61.37 mg.kg-1.dwt (1.4E-4±7.0E-5, 1.35E-3±4.1E-4, 6.03E-3±2.21E-3, 1.05E-3±2.8E-4, 6.9E-4±3.1E-4 ,1.07E-3±3.8E-4, 0.97±3.08E-1, 8.25E-3±1.7E-3 and 6.91E-3±2.16E-3 oz.lb.-1.dwt), respectively. Most of these levels exceeded the permissible limits set by the World Health Organization and typical background values. Pollution indices suggested that the soil ranged from unpolluted to moderately polluted, with Cd, Co, Cr, and Zn being of particular concern. Cadmium was found to be the primary contributor to ecological risk, mainly from anthropogenic sources. Principal component analysis identified four key components: PC1 was dominated by Cd, Pb, and Zn with moderate contributions from Cu, related to human activities; PC2 was dominated by Fe and Cr; PC3 by Ni and Mn; and PC4 by Co and Cu, primarily from natural sources.