Assessment of Cd, Pb and Zn contamination in roadside soils and grasses from Gipuzkoa (Spain)

Superficial soils and grasses at two distances from eight different locations near to roads varying traffic flow were collected in July of 1992 and July of 1994. Total (soil and grass) and DTPA=extractable (soil) contents of Cadmium, Copper, Iron, Manganese, Lead and Zinc were determined by Atomic Absorption Spectroscopy. Remarkable high levels of Pb and Zn in the nearest point to A-8 highway were found. The application of statistical treatment showed for Cd, Cu, Pb and Zn significant correlations between DTPA-extractable and total contents and also the variability with distance and locations. However, the 1992 and 1994 samplings did not significantly differ neither in the total concentrations nor in the extractable levels. Using factor analysis a strong association among Cd, Pb and Zn indicating the same pollution source was found.