The accumulation of heavy metals Pb, Cu and Cd at roadside forest soil

The accumulation of heavy metals at the roadside has been studied by the analysis of topsoil samples. Concentrations of the elements Pb, Cu and Cd were measured on 81 topsoil samples collected from three similar sites located near the Vilnius-Klaipėda highway. The soluble and total content of heavy metals was determined in fractions >2mm by atomic absorption spectrophotometer employing an air–acetylene flame. Different chemical extractants AAAc-EDTA and DTPA were used for determination of extractable elements. The comparison of the results indicates that AAAc-EDTA extraction solution is the most efficient and well suited for determination of Pb, Cu and Cd. The highest heavy metals concentration was found at a distance of 5 meters from the road and it exceeded the local background in the forest soils for all metals. Contents of metals tended to decrease with increasing distance from the highway. The results showed that the soil near the highway had significant enrichment, particularly in Pb, whose easily mobile amount exceeded maximal limited concentrations at a distance of 5-40 meters, and to a lesser extent with Cd and Cu.