Assessment of heavy metals contamination in deposited street dusts in different urbanized areas in the city of Ma'an, Jordan

摘要

190 Street dust samples were collected from nine different localities including high traffic (desert highway), moderate traffic (city center), light traffic (minor streets), residential streets, school gardens, hospital and health centers, industrial sites, parks and background sites (control) of Ma'an area. The concentrations of Fe, Zn, Ni, Pb, Mn, Cu and Cd were analyzed by flame atomic absorption spectrophotometer to assess and to compare road dust contamination levels of metals among the different types of urban environment. The results showed that dust samples from the urban and industrial site contained significant levels of the metals studied compared to the values obtained from the background site. The variation in concentration of the heavy metals determined from different locations was in the decreasing order as: industrial ＞ high traffic ＞ parks ＞ moderate traffic ＞ hospital and health centers ＞ school gardens ＞ light traffic ＞ background sites. The mean concentrations of the metals were in the order of C_(Fe) ＞ C_(Zn) ＞ C_(Ni) ＞ C_(Pb) ＞ C_(Mn) ＞ C_(Cu) ＞ C_(Cd) where C is the concentration of these metals in solution. Enrichment factor calculations indicated that Cd, Pb, Zn and Ni were highly enriched. Fossil fuel combustion, wear of brake lining materials, traffic emissions and several industrial processes are considered the main sources of these metals. Assessment of the contamination level in dust sample was estimated based on the geoaccumula-tion index (I_(geo)), the pollution index, and integrated pollution index (IPI). The values of IPI are in the following order: Pb ＞ Zn ＞ Cu ＞ Ni ＞ Cd ＞ Mn. All the indices for the metals under consideration were either low or corresponded to middle level of contamination. The use of factor analysis showed that anthropogenic activities seem to be the responsible source of contamination for metals in dust samples.