Testing the concentration of trace metals in soils near roads with varied traffic intensity

Motor transport affects the state of the natural environment and results in the accumulation of trace metals in roadside soils. The trace metal concentrations in roadside soils depend mainly on the distance from the road and the traffic intensity. The aim of the investigations was to determine the range of the environmental impact of the (Cracow-Zakopane) transport route and the effect of traffic intensity on the concentrations of trace metals in the soil. Three road sections differing in their traffic intensity were selected for this purpose. The concentrations of Cr, Cu, Ni, Pb and Zn in soil samples taken from a depth of 0-30 cm at a distance of 5, 10, 50 and 100 metres from the road were spectrophotometrically determined. The metal concentrations in the surroundings of the Cracow-Myślenice road carrying heavy traffic were found to be several times higher than the ones in the soils near the Łopuszna-Dursztyn local road with low traffic intensity. The largest differences in trace metal concentrations in the soils were found for nickel (four times higher concentrations along the Cracow-Myślenice road) at all the considered distances and for copper (three times higher) at the distances of 5 and 10 metres. In comparison with the reference areas, in the vicinity of the investigated roads the concentrations of Cr, Cu, Ni, Pb and Zn in the soil were found to be elevated. The fact that the concentrations of the trace metals decrease with increasing distance from the road's edge clearly indicates the traffic-related origin of the contaminants.