Abstract Soil samples were collected from three asphalt hot mix stations and examined for heavy metals using standard procedures. The results obtained showed that the concentrations of the heavy metals occurred in the order; iron (Fe)>zinc (Zn)>chromium (Cr)>lead (Pb)>copper (Cu)>nickel (Ni)>arsenic (As)>cobalt (Co)> cadmium (Cd). All the metals examined in the soil were lower than the reference value stipulated by DPR except As and Cd and Co in stations 2 (JADAC HMX) and 3 (H & H (HMA) respectively. Contamination factor studies on the concentrations of the heavy metals in the soil showed various degrees of contamination by the heavy metals except As and Cd and Cu in station 3and cobalt in stations 2 and 3 that have stretched to pollution status in the soil. Pollution index analysis showed that the soils from the various asphalt plant stations were slightly polluted with the heavy metals. Contamination factor evaluation of metals varied from considerable contamination degree to high contamination degree in the stations. Modified contamination degree analysis revealed that all the stations were at a level of moderate degree of contamination by the heavy metals. Geo-accumulation findings revealed a variation between non-contaminations to extreme contamination of the soil with individual heavy metals. Ecological risk assessment of the soils suggested varying degrees of risks posed by each metal to the environment. Enrichment factor analysis revealed serious anthropogenic influence on the metal content of the soil. The results obtained from the stations in this study coupled with the different analytical assessments showed that human activities are the major contributors of the heavy metals in the examined soils.
Keywords Heavy metals, Asphalt plants, pollution assessment indices, Environment, anthropogenic sources.