Using Pollution Indexes to Assessment of Heavy Metals Pollution in Highway – Side Soils around Baghdad City

Abstract

Assessment of heavy metal pollutants: Cd, Pb, Zn and Ni was conducted for Soils in surrounding highway of Baghdad city, evaluate the relation between heavy metals concentration in soil, and study effect of distance from pollution source. Study area was including high express way surrounded Baghdad city, in 43 km distance approximately. Four pollution indexes had been used enrichment factor ratios (EF), contamination factor (CF), pollution load index (PLI) and geoaccumulation index (Igeo) methods, to assessment of heavy metals pollution for these Soils.

Results showed that heavy metals concentrations in soil samples took the order of Ni > Zn > Pb > Cd and all was higher than their concentration in comparison soils. The EF and PLI values decreased with increasing distance away of the highway edges for both sides with random distribution in some locations. This indicated to the affected soils of near sites of 1.5 and 10 m from road sides by emitted gases from vehicles exhausts that used the road. The CF values of Cd, Pb, Zn and Ni for all studied soils ranged of lower – moderately polluted (1 > CF – 3 > CF ≥ 1). All values of I_geo were within the range 1 > I_geo ≥ 0 considered as values ranged between non-pollution – moderately pollution, thus the contribution of geo source supplying with heavy metals was in the lower level. Results indicated that heavy metals concentrations appeared through pollution indexes calculations (EF, CF, PLI and I_geo) were from human activities (anthropogenic source), which support assumption of those soils affected by gases emitted from vehicle exhausts or other human activities.

Key words: Heavy metal contamination, roadside soils, enrichment factors, contamination factor, pollution load index, geoaccumulation index, Baghdad, Iraq, AAS.