POLLUTION ASSESSMENT OF MANGANESE, ZINC, CHROMIUM, LEAD, COPPER AND NICKEL IN BUS STOP DUSTS OF QINGYANG CITY, NORTHWEST CHINA

To know the effects of human activities on semi-arid environmental quality, fifty-three bus stop dusts samples were collected from Qingyang city, NW China and the contents of manganese (Mn), zinc (Zn), chromium (Cr), lead (Pb), copper (Cu) and nickel (Ni) in these samples were measured by X-ray fluorescence spectrometry. The results indicate that the dust samples have elevated Cr, Cu, Zn and Pb concentrations in comparison with local soil. The contamination levels of these heavy metals in bus stop dusts were evaluated by enrichment factor (EF), pollution index (PI) and Nemero synthesis pollution index (NSPI). The average EF value increased in Ni < Mn < Cr < Cu < Zn < Pb. The higher EF of Cu, Zn and Pb turns out that there were considerable Cu, Zn and Pb pollution in bus stop dusts. The low EF for Ni, Mn and Cr indicates that there were absent of distinct Ni, Mn and Cr pollution in bus stop dusts. The results of PI also support that Cu, Zn and Pb in bus stop dusts from Qingyang city were middle contamination, and the NSPI values in 98.1 % bus stop dusts samples reveals heavy contamination.