Pollution of potentially toxic metals in urban road dust in Dushanbe (Tajikistan)

Abstract

Heavy metal contamination in the road dust due to traffic in the capital city of Tajikistan was investigated. Concentrations of potentially toxic elements (Ba, Cu, Cd, Co, Cr, Pb, Ni, Zn and As) in particle size of 63 μm were analyzed. The highest potentially toxic element concentration was Zn (312 mg/kg), whereas the lowest was Co (5.3 mg/kg).The biggest contribution to road dust is atmospheric deposition due to metal traffic density makes slight contribution to heavy metal contamination. According to the calculation on enrichment factor (EF), heavy metals decrease in the order of Sb>Cd>As>Cu>Zn>Pb. The Dushanbe city road dust particles are potentially influenced by minimum three sources of metals including: Urban sources (vehicles traffic, etc.); industrial sources (cement, reinforcement plant, etc.); geogenic sources (soils, dusts, rock weathering, etc.).