Abstract The heavy metal contents of five sampling points adjacent to roads of varying traffic flow in Guipuzcoa (Spain) were determined. At every point two topsoil samples separated 2–3 m were taken in July 1991. The soil samples were digested with aqua regia and extracted with DTPA. Cd, Cu, Fe, Mn, Ni, Pb and Zn were determined by flame or graphite furnace atomic absorption spectrophotometry. Significant correlations between aqua regia metal levels and DTPA-extractable metal levels were found for Zn, Pb, Cu, Cd and Ni. Most of the metal levels decreased with distance from the source of pollution. The quantity of several metals, mainly Pb and Zn, in the samples increased with the traffic flow. There was a point where the proximity of an industrial area had a major effect on the quantity of several metals.
R. García, Esmeralda Millán
Science of The Total Environment