Evaluation of Heavy Metal Contamination in Soils along National Highway 2 (NH2)—A Case Study

The concentration of heavy metals in roadside soil samples (RSS) is evaluated from selected sites along National Highway 2 lying between Jharkhand-West Bengal. Soil samples were collected at distance range of 0, 5, 20, 50 m from the road, in addition to the middle position/divider crosswise. The results were made in comparison with control site, based on contamination factor (CF), degree of contamination (CD), pollution load index (PLI), and geo-accumulation index (I_geo). Contamination indices showing pollution trend and mean concentration of the metals were analysed relative to control. The values of pollution level index (P_LIdx) obtained for these five sites (P_LIdx > 1) indicate deterioration of site quality. Significant correlation between some of the metals (Cd, Cr, Cu, Ni, Pb, and Zn) studied and average daily traffic volume showed that the contamination of heavy metals could be from automobile emissions and it decreases in RSS as the distance increases from the road edge. The investigation is highly necessary to study concentrations and health implications of these metals in residents of linear settlements along this major road as no research work in heavy metal contamination on roadside soil has been done till date. The present study will also serve to create awareness of vehicular heavy metal pollution in roadside soil.