The Impact of Vehicle Traffic on the Amount of Lead and Cadmium Accumulation in Soil and Alfalfa on the Sidelines of the Road (Saveh - Hamedan)

Considering the contamination resulting from heavy metals including Pb and Cd and the challenges of such contamination for plants and human beings, the present experiment was carried out to investigate the amount of the accumulation of these two metal types in the soil and alfalfa plant growing on the sidelines of Saveh-Hamedan road. Soil and plant samples were collected from the 10-, 20-, 40-, 80-, 160-, and 240-meter distances from the roadsides in 2012, following a randomized complete block design. The total amount of Lead and Cadmium absorbed in soil together with the concentration of these two metal types in the root and shoot of alfalfa plant were measured. The results indicated that the total and available amounts of Lead in the soil, 10 meters away from the roadside, were respectively 3.24% and 21.69% more than the amount obtained from the soil 240 meters away. The highest amount of Lead in the root and shoot of the plant was obtained from the 10-meter distance from the roadside which was respectively 6.31% and 5.30% more than the amount obtained from a 240-meter distance. The highest amount of Cadmium in the shoot and root of alfalfa belonged to the 240-meter distance from the roadside. Additionally, Lead accumulation in the shoot was more than the root. The factor of Pb transfer was above one across all seasons while Cadmium had a transfer factor below one. Accordingly, livestock feed from the shoot of this plant in contaminated environments threatens livestock’s and consequently human’s health.