ABSTRACT

This study has been conducted in January 2019 to assess the heavy metal contamination in soils of road site from Mymensingh to Valuka focusing the vehicles emission run on highway. Sixteen (16) soil samples were collected consisting of road side traffic area soil and adjacent to road side near agricultural field soil (within) 100m. The samples were digested with acid mixture (HNO3:HClO4=2:1) and then the concentrations of four heavy metals Zn, Pb, Cr, and Cd were determined using Atomic Absorption Spectrophotometer (AAS). For assessing the contamination levels of heavy metals, contamination factors (CF), degree of contamination (Cd), index of geo-accumulation (Igeo) were measured comparing with the international standard. Elevated metal concentrations were found in road site soil samples. The geo-accumulation index (Igeo) indicated that the road was moderately polluted by Zn, moderately to strongly pollute by Pb, whereas field soils were free from Zn and Pb contamination. Cr and Cd were unpolluted in both types of soils. The values of contamination factor (CF) existed as Pb> Zn > Cd > Cr for the road side soil. The values of contamination factor (CF) existed for agricultural field soil ranked as Zn >Pb> Cd >Cr. The degree of contamination of all sampling sites show very moderate to low degree of contamination. Pollution load index calculated from the CFs indicated that Zn and Pb are the major pollutants in the studied road side soils along Mymensingh to Valuka highway.

Key words: Heavy metals, contamination, highway soil.